Tilting at Windmills, Spain’s disastrous attempt to replace fossil fuels with Solar Photovoltaics

Book review of “Spain’s Photovoltaic Revolution. The Energy Return on Investment”, by Pedro Prieto and Charles A.S. Hall. 2013. Springer.

Reviewed by Alice Friedemann, www.energyskeptic.com, last updated May 26, 2016


2016-05-26 The real EROI of photovoltaic systems: Professor Hall weighs in

May 8, 2016: a recent paper in Energy Policy on the EROI of photovoltaic solar systems came up with a NEGATIVE EROI of 0.85:1. Ferrucio Ferroni and Robert J. Hopkirk conclude: “At least at today’s state of development, PV technology cannot offer an energy source but a NET ENERGY LOSS, since its ERoEIEXT is not only very far from the minimum value of 5 for sustainability suggested by Murhpy and Hall (2011), but is less than 1 [0.85].

Prieto (private communication) notes that “Ferroni/Hopkirk calculate the failure rates of PV modules as per the public statistics of PV Cycle (a recycling European entity), that do not count modules that are simply abandoned.  The data contradicts the IEA PVPS program, calculating 30 years of life span for PV systems: the failure rates give a figure much closer to 18 years.”  

Prieto also says that a criticism of their paper is that Spain is a lousy country, but Germany is the “flagship of perfect workmanship”. Yet after 10 years, the reality is that Spain is producing twice as much energy as Germany in per MWp installed basis, not only because Spain is better irradiated (about 50%), but also because of the more efficient and better maintained utility scale installations in Spain versus the scattered rooftop individual home installation in Germany.” He also notes that the Ferroni (2016) paper “is dramatic and is raising some blisters.”

Ferroni, F., Hopkirk, R. J. 2016. Energy Return on Energy Invested(ERoEI)for photovoltaic solar systems in regions of moderate insolation. Energy Policy 94:336–344

April 11, 2015: responses from Prieto on criticism received at the 2015 Stanford University Net Energy Conference and the attempted suppression of  publication of this book, plus Ted Trainer’s response 

Spain Olmedilla 60 MW Solar PV plantOlmedilla, Spain 60MW Solar Photovoltaic Power Plant. Source: SolarNovus Large Solar Installations around the world.

Note to readers: Charles Hall is one of the originators of the concept of EROI (along with Howard Odum and many others). As a tenured professor not funded by any special interests, he is one of the most respected, cited, and unbiased scientists writing on EROI. I found this description of Hall at an excellent article about energy storage and EROI by John Morgan:

“…US fisheries ecologist Charles Hall noted that the energy a predator gained from eating prey had to exceed the energy expended in catching it. In 1981, Hall applied this net energy analysis to our own power generation activities, charting the decline of the EROI of US oil as ever more drilling was required to yield a given quantity, and suggesting the possibility that oil may one day take more energy to extract than it yields. Hall and others have since estimated the EROI for various power sources, a difficult analysis that requires identification of all energy inputs to power production. EROI is a fundamental thermodynamic metric on power generation. Net energy analysis affords high-level insights that may not be evident from looking at factors such as energy costs, technological development, efficiency and fuel reserves, and sets real bounds on future energy pathways. It is unfortunately largely absent from energy and climate policy development.”

Finally, the first and only book to use massive amounts of real data, not models

This is the only estimate of Energy Returned on Invested (EROI) study of solar Photovoltaics (PV) based on real data.  Other studies use models, or very limited data further hampered by missing figures about lifespan, performance, and so on that are often unavailable due to the private, proprietary nature of solar PV companies.

Models often limit their life cycle or EROI analysis to just the solar panels themselves, which represents only a third of the overall energy embodied in solar PV plants. These studies left out dozens of energy inputs, leading to overestimates of energy such as payback time of 1-2 years (Fthenakis), EROI 8.3 (Bankier), and EROI of 5.9 to 11.8 (Raugei et al).

Prieto and Hall used government data from Spain, the sunniest European country, with accurate measures of generated energy from over 50,000 installations using several years of real-life data from optimized, efficient, multi-megawatt and well-oriented facilities.  These large installations are far less expensive and more efficient than rooftop solar-PV.

Prieto and Hall added dozens of energy inputs missing from past solar PV analyses.  Perhaps previous studies missed these inputs because their authors weren’t overseeing several large photovoltaic projects and signing every purchase order like author Pedro Prieto. Charles A. S. Hall is one of the foremost experts in the world on the calculation of EROI.  Together they’re a formidable team with data, methodology, and expertise that will be hard to refute.

Prieto and Hall conclude that the EROI of solar photovoltaic is only 2.45, very low despite Spain’s ideal sunny climate.  Germany’s EROI is probably 20 to 33% less (1.6 to 2), due to less sunlight and less efficient rooftop installations.

Spain saw much good coming from promoting solar power. There’d be long-term research and development, a Spanish solar industry, and many high-tech jobs created, since the components for the solar plants would be manufactured locally. Spain imports 90% of its fossil fuels, more than any other European nation, so this would lower expensive oil imports as well.

To kick start the solar revolution, the Spanish government promised massive subsidies to solar PV providers at 5.75 times the cost of fossil fuel generated electricity for 25 years (about a 20% profit), and 4.6 times as much after that.  Eventually it was hoped that solar power would be as cheap as power generated by fossil fuels.

Financial Fiasco

The gold rush to get the subsidy of 47 Euro cents per kWh began.  Because the subsidy was so high, far too many solar PV plants were built quickly — more than the government could afford.  This might not have happened if global banks hadn’t got involved and handed out credit like candy.

Even before the financial crash of 2008 the Spanish government began to balk at paying the full subsidies, and after the 2008 crash (which was partly brought on by this over-investment in solar PV), the government began issuing dozens of decrees lowering the subsidies and allowed profit margins. In addition, utilities were allowed to raise their electric rates by up to 20%.

The end result was a massive transfer of public wealth to private solar PV investors of about $2.33 billion euros per year, and businesses that depended on cheap electricity threatened to leave Spain.

Despite these measures, the government is still spending about $10.5 billion a year on renewable energy subsidies, and the Spanish government has had many lawsuits brought against them for lowering subsidies and profit margins.

Solar companies went bankrupt after the financial crash, including the Chinese company Suntech, which sold 40% of its product to Spain.  About 44,000 of the nation’s 57,900 PV installations are almost bankrupt, and companies continue to fail (Cel Celis), or lay off many employees (Spanish photovoltaic module manufacturer T-Solar).

Nor were new jobs, research, and development created, since most of the equipment and solar panels were bought from China.  But unlike China, where the government insisted PV manufacturing be supported by massive research and development (and cybertheft of intellectual property from the United States and other nations), the only “innovations” capitalists in Spain sought were the numerous financial instruments they “invented” to make money, such as “solar mutual funds”.  Far more money went into promoting and selling solar investments than research and development.

Prieto and Hall believe this fiasco could have been avoided if the Spanish government had invited energy and financial analysts to flow-chart the many costs and energy inputs to have had a more realistic understanding of what the costs would be versus the extremely small amount of electricity added to Spain’s electric supply.

Spain’s largest renewable energy company, Abengoa, could soon become Spain’s largest bankruptcy. Abengoa’s stock price has plunged over 50%, reducing its market value half a billion dollars. As a result, Abengoa began insolvency proceedings that give the firm just four months to find a buyer or reach an agreement with its creditors. Abengoa has invested more than $3 billion in renewable energy projects in the United States, including several utility-scale concentrated solar power projects. Most of Abengoa’s renewable energy assets in the U.S. are owned by Abengoa Yield, the U.S.-based subsidiary of the Spanish renewable energy company. The U.S. Department of Energy provided a federal loan guarantee of $1.45 billion for Abengoa’s 280 megawatt (MW) Solana project in Arizona, the largest parabolic trough plant in the world. Abengoa is also developing the 280 MW Mojave Solar project in California, which also used parabolic trough technology. Abengoa has also invested more than $1.4 billion in more than half a dozen U.S. ethanol and advanced biofuels plants. Although Abengoa owns a 47% equity stake in Abengoa Yield, the subsidiary has thus far managed to limit the financial fallout from the problems at its parent company. That may soon change. Abengoa Yield is tied to Abengoa through a series of cross default clauses included the debt agreements used to finance several projects (Pentland 2015).

Germany’s is having a similar financial solar power fiasco

Germany has spent about $100 billion Euros between 2000-2011 according to Alexander Neubacher’s article in Der Spiegel  Solar Subsidy Sinkhole: Re-Evaluating Germany’s Blind Faith in the Sun (some excerpts below):

“For weeks now, the 1.1 million solar power systems in Germany have generated almost no electricity. The days are short, the weather is bad and the sky is overcast. As is so often the case in winter, all solar panels more or less stopped generating electricity at the same time.

To avert power shortages, Germany imports large amounts of electricity generated at nuclear power plants in France and the Czech Republic and powering up an old oil-fired plant in the Austrian city of Graz.

Solar farm operators and homeowners with solar panels on their roofs collected more than €8 billion ($10.2 billion) in subsidies in 2011, but the electricity they generated made up only about 3% of the total power supply at unpredictable times.

The distribution networks are not designed to allow tens of thousands of solar panel owners to switch at will between drawing electricity from the grid and feeding power into it.

Because there are almost no storage options, the excess energy has to be destroyed at substantial cost. German consumers already complain about having to pay the second-highest electricity prices in Europe.

Under Germany’s Renewable Energy Law, each new system qualifies for 20 years of subsidies. A mountain of future payment obligations is beginning to take shape in front of consumers’ eyes.

According to the Rhine-Westphalia Institute for Economic Research (RWI), the solar energy systems connected to the grid in 2011 alone will cost electricity customers about €18 billion in subsidy costs over the next 20 years. The RWI also expects the green energy surcharge on electricity bills to go up again soon. It is currently 3.59 cents per kilowatt hour of electricity, a number the German government had actually pledged to cap at 3.5 cents. But because of the most recent developments, RWI expert Frondel predicts that the surcharge will soon increase to 4.7 cents per kilowatt hour. For the average family, this would amount to an additional charge of about €200 a year, in addition to the actual cost of electricity. Solar energy has the potential to become the most expensive mistake in German environmental policy.

Solar lobbyists like to dazzle the public with impressive figures on the capability of solar energy. For example, they say that all installed systems together could generate a nominal output of more than 20 gigawatts, or twice as much energy as is currently being produced by the remaining German nuclear power plants.

But this is pure theory. The solar energy systems can only operate at this peak capacity when optimally exposed to the sun’s rays (1,000 watts per square meter), at an optimum angle (48.2 degrees) and at the ideal solar module temperature (25 degrees Celsius, or 77 degrees Fahrenheit) — in other words, under conditions that hardly ever exist outside a laboratory.

In fact, all German solar energy systems combined produce less electricity than two nuclear power plants. And even that number is sugarcoated, because solar energy in a relatively cloudy country like Germany has to be backed up with reserve power plants. This leads to a costly, and basically unnecessary, dual structure.

Because of the poor electricity yield, solar energy production also saves little in the way of harmful carbon dioxide emissions, especially compared to other possible subsidization programs. To avoid a ton of CO2 emissions, one can spend €5 on insulating the roof of an old building, invest €20 in a new gas-fired power plant or sink about €500 into a new solar energy system.

Former industry giant Solarworld, based in the western city of Bonn, is having problems. Solon and Solar Millennium, once considered model companies, have gone out of business. Schott Solar shut down a plant that was producing solar cells in Alzenau near Frankfurt, shedding 276 jobs and losing €16 million in government subsidies in the process.”

So is Japan

If every solar plant now on the drawing board were actually to be built in the Japanese region of Kyushu, it would cost users $23 billion, four times the premium they’re paying now. Solar power here is costly for consumers because of high state-mandated prices. Utilities say their infrastructure cannot handle the swelling army of solar entrepreneurs intent on selling their power or handle the fluctuating output of thousands of mostly small solar producers.  To do this, utilities need to install more hardware — transmission cables, substations and the like — and develop new kinds of expertise to avoid disruptions. To make renewables work they have to be properly connected to the power system. Installed solar capacity roughly doubled  since 2012, when a law took effect requiring utilities to buy renewable energy from outside producers at rates far above market prices. By last summer it stood at 3.4 gigawatts, about equal to the output of three modern nuclear reactors but only when the sun was shining at full strength. An additional 8.4 gigawatts’ worth of projects are planned, more power than the region consumes on some low-demand days — and far too much for Kyushu Electric’s grid to handle without the risk of failures.  New transmission cables are being laid but progress is slowed by the expensive task of securing land rights (Soble).

A realistic look at solar PV can give us better ideas of how to cope in the future

Solar advocates can learn from this analysis as well to design solar PV with far less dependency on fossil fuels.  That can only be done by realistically looking at all of the inputs required to build a solar PV plant.  Narrowing the boundaries to avoid these realities is not good science and leads to wasted money and energy that could have been better spent preparing more wisely for declining fossil fuels in the future such as Heinberg’s “50 Million Farmers“.

Some energy statistics


  • The world burns 400 EJ of power, though after fossil fuels begin their steep decline, there will be 10-20 EJ less per year.
  • Very large oil fields provide 80% of oil, and they’re declining from 2 to 20% per year, on average at 6.7%.
  • The exponential decline rate is expected to increase to 9% if not enough investments are made – and perhaps 9% or more even with investments
  • Oil is the basis of 97% of transportation

Spain’s solar photovoltaic electricity

  • It’s the 2nd largest installation of PV on earth
  • Produces about 10% of the world’s PV power: 4,237 MW—equal to four large 1000 MW coal or nuclear power plants
  • Solar PV would have to cover 2,300 square miles to replace the energy of nuclear and fossil fuel plants.  You’d also need the equivalent of 300 billion car batteries to store power for night-time consumers (Nikiforuk).
  • In 2009, these plants generated 2.26% of Spain’s electricity, the largest percent of any nation in the world

2009 Types of PV Installations in Spain (ASIF. July 2010 report)

  • 63%        Fixed plants
  • 13%        1-axis trackers
  • 24%        2-axis trackers

Types of PV Used 

  •     .6%     HCPV
  •   2.1%     Thin Film
  • 97.3%     Crystalline silicon

Amount of Power generated

  • 36%     < 2 MW
  • 20%     2-5 MW
  • 44%     > 5 MW

Where were the PV panels placed

  •   2.2     Rooftop
  • 97.8     On the ground (far more efficient than rooftop)

Why wasn’t as much power produced as promised?

Only 66% of the nameplate, or peak power, was actually delivered over 2009, 2010, and 2011.  The expected amount was 1,717 GWh/MWn but only 1,372 GWh/MWn were produced.

Typical losses in Performance Ration (PR) analysis (see Slide 14)

% Loss is the “loss factor in % over nameplate”

% Loss     Reason

0.6       Mismatch of modules. One bad apple and all the rest are reduced to the lowest common denominator — the least efficient module. Mismatches can occur from irregular shading, ice, dust, and other problems.

1.0     Dust losses can be as high as 4 to 6% if washing isn’t done often enough

1.0     Angular and Spectral loss of reflection when the PV isn’t directly aimed at the sun

5.5     Losses due to temperature

1.0     Maximum power point tracker

1.0     DC wiring

5.4     AC/DC output of inverter

0.4     AC wiring within the PV plant

2.1     Medium-voltage losses within the plant

0.0     Non-fulfillment of nominal power, Shadowing/Shading, voltage sags, swells, etc

Performance Ratio: 82

Other losses beyond the typical Performance Ratio: extended performance ratio factors

8.0     Peak versus nominal installed power factoring

2.0     Losses in the evacuation/connection line/transformers

11.4     Degradation of modules over time

Will PV modules really last for 25 years?  If not, the EROI is less than 2.45

Prieto and Hall distributed the Energy Invested across 25 years, but it is not likely that PV (and other manufacturers) will honor their contracts for that long:

  1. Many manufacturers are already out of business, and many more will go out of business as their level of technology falls behind advancements elsewhere in the world. Companies who took on lots of debt expecting higher subsidies are failing now and will continue to do so.
  2. Events of Force Majeure, acts of god, wind, lightning, storms, floods, and hail are likely to damage facilities within the next 25 years.
  3. The degradation of PV modules may be higher than 1%/year up to a maximum of 20% over 25 years. This figure was very hard to come by, since Solar PV manufacturers don’t like to reveal it. Prieto & Hall found out by looking at commercial contracts.
  4. Any component that degrades or fails, not just the PV itself, will lower the overall EROI.
  5. As fossil fuels decline, it will be hard to find the resources to maintain society. These plants will not be high priority, since dwindling diesel fuel will be diverted to agriculture, trucks, and other more essential services.
  6. Once fossil fuels begin their steep decline, social unrest will make it hard for businesses to operate.

Low EROI: The Devil is in the Details

Most of the book explains the methodology and details of how EROI was calculated. The level of detail even extends to each of the three types of facilities (fixed, 1-axis, 2-axis) for many factors.  Below is a partial summary of the Energy Invested table 6.18 in the book with the Energy Invested and money-to-energy columns missing. You can also see an older version in slide 18).  Economic expenses (not shown) were converted to GWh/year energy equivalents and spread across 25 years.  The book goes to great lengths to explain how they converted money to EROI equivalents.

GWh/year        Factors


56.6   Foundations, canals, fences, accesses

4.7   Evacuation lines and right of way

11.2   Module washing and cleaning

28.2   Self consumption in plants

138.6   Security and surveillance


608      Modules, inverters, trackers, metallic infrastructure (labor not included)


96      Transportation (locally in Spain, international (i.e. China)

148.4   Premature phase out of unamortized manufacturing and other equipment

0       Energy costs of injection of intermittent loads; massive storage systems

(i.e. pump-up costs)

19.9   Insurance

26.4   Fairs, exhibitions, promotions, conferences

34.3   Administrative expenses

14      Municipal taxes etc (2-4% of total project)

8.7   Land cost (to rent or own)

16      Indirect labor (consultants, notary publics, civil servants, legal costs, etc)

6      Market or Agent representative

11.9   Equipment theft and vandalism

0      Pre-inscription, inscription, registration, bonds & fees

178      Electrical network / power line restructuring

39.6   Faulty modules, inverters, trackers

198      Associated energy costs to injection of intermittent loads; network stabilization associated costs (combined cycles)

0          Force majeure: Acts of God, wind, storms, lightning, storms, floods, hail

The 2,065.3 GWe of the above energy inputs used annually to generate electricity is 40.8% of all the electricity generated by the solar PV plants of Spain, resulting in an EROI of 2.45 (1/.408).

Most life-cycle analyses only consider the 608 GWe of the modules, inverters, etc.  They also usually ignore some or all of the Balance of System energy expenses (energy used on-site) and the remaining factors.

I can’t resist a few examples to give you an idea of how complex a solar PV plant is. Every factor had complications and nuances that made this book very interesting and entertaining to read.

The access roads from the main highway to the plant, which across all the PV plants in Spain added up to about 300 km (186 miles),  used 450,000 m3 or 900,000 tons of gravel.  That takes 90,000 truckloads of 10 tons each traveling an average of 60 km round-trip, or 5,400,000 km (3,355,400 miles) at .31 of diesel per km or 1,620,000 liters of diesel. At 10.7 KWh/liter, that’s 17.3 GWh of fuel.  Then you need to add the energy used by other equipment, such as road rollers, shovels, pickups, and cars for personnel, and the energy to grind, mix, and prepare the gravel and the machinery required.

There are also service roads onsite to inverters, transformers, and distributed station housings, the control center, and corridors between rows of modules.  There are foundations and canals.  A total of 1,572,340 tons of concrete was used, requiring 489.3 GWh of energy.

Surrounding all these facilities are fences 2 meters high that used 3,350 tons of galvanized steel, and another 3,350 tons of steel posts, or 385 GWh of energy.

Washing and cleaning Solar Panels

Solar plants tend to be in desert-like surroundings with little water. Spain is so short on water they’ve got the 4th largest desalinization capacity in the world. Solar PV can’t be washed with tap or well water because they leave calcium and mineralized salts which degrade the PV performance, and can even scratch them.  So the water has to be de-mineralized, decalcified, and sometimes even de-ionized. Washing might take place on average four times per year, but that’s not nearly enough – dust storms and dust from agriculture plowing can happen any time of the year, perhaps even right after they’ve been washed.

Critics of their book dismiss these issues by mentioning various techno-fixes.  Across all technologies, whether it’s biofuels or nuclear power, this is an easy way for pepole who want to believe in something to dismiss criticism.  So for the dust problem here’s an example of how the problem has been “solved”.    Critics reply that the technology exists to use an electrostatic charge to repel dust and force it to the edges of the panels. But when you look into this, you find that the technology was developed for NASA to use on Mars back in 2010.  On earth, this technology has to compete with cheaper technologies such as blowing air or adding a non-stick layer.  And on Earth, it doesn’t work if the dust gets wet and turns to mud.   Consider how much EROI (and money) it would cost to replace all of Spain’s solar panels to have this feature.  The panels can’t be modified because it’s embedded in the panel using “a transparent electrode material such as indium tin oxide to deliver an alternating current to the top surface of the panel.”  That will take some EROI as well.  Indium is very expensive — it’s a rare earth metal, and the U.S. Department of Energy considers it critically rare for the next 5 years. China has 73% of the world’s Indium reserves, refines half of it, and limits exports.  The USA has been 100% dependent on indium imports since 1972.  The U.S. DOE says reductions in “non-clean energy demand” will be needed “to prevent shortages and price spikes”. This article also pointed out that dust storms reduced power production by 40 percent at a large, 10-megawatt solar power plant in the United Arab Emirates.  I wonder how bad the dust storms are in Spain?  Will the 2nd edition of Prieto & Hall’s book reduce the EROI even further?  (Bullis).

Cheaper and More Efficient DOESN’T MATTER: PV is only 1/3 of the EROI

Critics of this book will say cheaper and more efficient PV cells are on the way.  But as Prieto and Hall point out, the most effect an improved solar PV could have on the overall EROI is a maximum of 1/3 because of all the other factors.  Plus EROI goes down every time the oil price goes up, because that causes all of the other factors to increase.  Press releases of solar PV breakthroughs can be very exciting, but keep in mind that none of these past improvements could replace fossil fuels: thin-film, nanotechnology PV, cadmium telluride cells, organic cells, flexible cells, rollable sheets of PV for rooftops, slate modules, multi-junction cells, back-junction cells with 20-40% efficiency, PV grapheme, etc.

These improvements have costs, that’s part of what’s meant by the “premature phase out” factor.  Solar businesses and PV plants go bankrupt when out-competed if they can’t afford to make expensive alterations and retrofits.

Spain PV plants 20 MW and 22 MW 2-axisTwo axis tracking PV Plants of 20 MWn and 22.1 MWp. Slide 25 states that to replace a nuclear plant 1/3 that of Fukushima with solar PV, you’d need to expand the area above 430 times to 190 square miles. Photo Source: http://www.flickr.com/photos/87892847@N03

Energy Returned on Energy Invested (EROI)

[Also see pitfall 8 in Gail Tverberg: 8 pitfalls in evaluating green energy solutions]

EROI = Energy returned to society / Energy invested to get that energy

Hall and Prieto believe that solar is a low EROI technology.  Solar has too many energy costs and dependencies on fossil fuels throughout the life cycle to produce much energy. It’s more of a “fossil-fuel extender” because PV can’t replicate itself, let alone provide energy beyond that to human society.

Nor is solar PV carbon neutral.  Too many of the inputs require fossil fuels.

Solar PV doesn’t come close to providing the 12 or 13 EROI needed to run a complex civilization like ours.

In the introduction, the authors say that “we recognize that some of our inputs will be controversial. We leave it to the reader and to future analysts to make their own decisions about inclusivity and methods in general for a comprehensive analysis of EROI. Whatever your opinion, this study should really open your eyes to the degree to which fossil fuels underlie everything we do in our technological society.”

But I would argue the boundaries can’t possible capture all the oil-based antecedents.  Fossil fuels are so embedded in every aspect of our life that we can’t see them. Think about solar PV when you read my summary of Leonard Read’s antecedents of a pencil.

April 1, 2015 update: Criticism of Prieto and Hall

I was at a net energy conference at Stanford University the past two days. The hoped for outcome is a new net energy think-tank that would standardize net energy by having a specific way researchers must conduct their studies, which LCA or other data tables are most-up-to-date and should be used, what assumptions they must state, and so on.  If researchers strayed from this format or added additional material, they’d need to say why.

The reason this needs to be done is because policy makers don’t take EROI studies seriously. Nor should they since they’re too easy to game by proponents (i.e. not counting the energy to make steel because it is 100% recycled, cherry-picking the best performing wind or solar farms over the best performing time period, etc).  Policy makers can’t be expected to make policy decisions or recommendations when EROI studies of a renewable ranges from 4 to 115.

Meta-studies can’t be done either because there is too much missing data, and/or unstated assumptions, and/or different models used, and rarely is real data available, since private companies don’t have to, and don’t want to reveal their true performance, operation, and maintenance costs or they’d get less investment and lower stock prices.

Yet even at the conference several EROI papers were not clear about their boundaries.  Long after the artificial photosynthesis presentation it came up that the outside boundary was set at 300 feet outside the factory gate.  Earlier they said the best guess EROI was 1.66, clearly if storage of the hydrogen produced, and delivery to the customer were added, the EROI is probably negative. The researcher implied that trying to combine the hydrogen with CO2 to make liquid fuels would be negative at this stage.  There may be a good reason why the boundary is 300 feet away, probably they assume that there’s a refinery nearby using the hydrogen to upgrade heavy or tarsand oil.

By the end of the conference I was a bit frustrated at the lack of discussion of boundaries.

This has been the main problem for 40 years and one of the big reasons why  studies come up with such different results.

So I asked the panel what they thought should be done about the boundary issue. For example, ethanol studies using narrow boundaries found higher EROI values than those with the widest boundaries, which often found a negative EROI.  Then I said that if there’s to be a discussion of how to set boundaries, I recommended Spain’s PV revolution by Prieto and Hall which used real production data over several years rather than models as a good way to decide  what to include or not include, and why, because I thought the boundaries should be as wide as possible. Also, since what you’re proposing is a mostly electric world, does that mean new standards will include the electricity used to make cement for the windmill and roads it travels on, the electricity to make the steel and fiberglass, and the electricity to make electric mining trucks and the electric delivery trucks that deliver the windmill?  And what would that electric delivery truck look like anyhow?

I had the strong impression this was not a welcome question. No one leaped to answer, and finally one of the panelists said that the boundaries ought to be wide but that this question was best talked about over a glass of wine.

After this session one of the speakers, Marco Raugei, at Oxford Brookes University, came over.  He was very upset by my question because he thought Prieto and Hall’s book was awful. He told me it was so bad that several scientists had tried to prevent Springer from printing it.

I told Raugei that I had looked very hard for any criticism of the book but had not been able to find any rebuttals, so what exactly was wrong with it?  Raugei replied that the book wasn’t peer-reviewed.  So I asked why someone didn’t write a paper to refute the book, and he said that since it wasn’t peer-reviewed, why bother, but I pointed out that Farrell in 2006 had used non peer-reviewed papers in his famous ethanol EROI study.  I don’t know if their book not being peer-reviewed is a valid criticism or not, does anyone know?

When I asked Raugei to tell me more about what was wrong, he said that it was inconsistent in so many ways, not defensible the way economic inputs were converted from money to energy such as the insurance figures, some air travel expenses, too haphazard, inconsistent in method and goal, not clear enough in stating that this is just one snapshot moment in time in Spain and that it used an ill-advised subsidy scheme, that the EROI is not the same in other countries and parts of the world, and that the goals should have been more explicitly explained.

What goals? I assume he thinks they try to come up with low EROI figures, which is outrageous, they have no special interests in pushing the result up or down.

If anything, Prieto ought to be skewing results towards a high solar PV EROI since he built some of the solar plants he writes about in the book.  He could make more money by touting solar PV rather than by criticizing it. Hall certainly has no dog in this fight.  In fact, if there were a way to have outsiders with no financial interest do EROI studies I’d be all for it, because parties with a financial interest tend to skew the results, such as the National Corn Growers Association funded scientists, who found the highest EROI results in their non-peer-reviewed papers.

I know there has been a firestorm of criticism of this book, but it’s all within private email, and the only one I have been privy to said that a better LCA database should have been used.

EROI is the only rational way to look at energy contraptions and to reach the right conclusions about what should be done.  I don’t have high hopes that a standardized way of doing EROI will be done.

It was ironic that Steven Chu was the opening keynote speaker at this net energy conference, since Patzek once wrote me that “Steven Chu decided not to fund my Laboratory Directed Research and Development (at Lawrence Berkeley Laboratory) project whose goal it would have been to arrive at a consistent thermodynamic description of all major energy capture schemes bio and fossil, so that we compare apples with apples. What I did not appreciate is that no one wants to know that they may be working on a senseless project, such as industrial hydrogen from algae. I despair seeing the rapid corruption and sovietization of American science (without the Soviet strengths in basic sciences), but can do little about it. … It is not easy to get funded on the subjects I have proposed.  …In fact, my LDRD proposal to develop the comprehensive thermodynamic language to talk about the different energy resources was just not funded…”

Someday when a future history of science author attempts to write about the history of EROI, I hope that Patzek, Hall, and others have written memoirs that discuss how hard it was to get funding, get published (did scientists really try to prevent Spain’s solar revolution from being published?!), the criticism they received, and so on, because I think it will be of great interest to the grandchildren and further generations down the line.  Understanding why renewables have such low EROI might prevent cargo-cult like behavior to spend huge amounts of resources and time to build them after the dark age that may ensue at some point on the downslope of Hubbert’s curve.

Pedro Prieto’s 4/11/15 response to criticism of his book:

(Bold is my emphasis):

Alice, as promised, let’s start answering and commenting on some of your wise comments.

The first thing is to confirm that no EROI studies can be taken seriously if the range of results varies so wildly. So it is quite a sensible approach to try to reconcile the different studies and methodologies.

Having said that, the prevailing methodology is what fails, specifically in the case of Solar PV analyses, but also in others. Experts in solar PV will have more and more available data as time passes from global installations.

Until now, we had seen many studies on different solar PV technologies with different typologies and topologies. Even before our book “ Spain’s Photovoltaic Revolution. The Energy Return on Investment” (Prieto & Hall. Springer 2013) appeared, there were already many variances and divergences.

Even works of Fthenakis or Raugei have contemplated significant variances in the EROI results over time and with different studies of solar plants.

But they all had a methodology in common: they generally used, as you have correctly pointed out, the best material recovery, the best theoretical solar PV system in each case, the best irradiated areas, the assumption that systems will operate in full along the lifetime with no problems. In summary, a methodology that has helped or served as documentary support or reference to many to reach global conclusions on the long term ability of modern renewables to replace, take over or substitute fossil fuels, from a given particular plant analysis extrapolated massively. That was the case, for instance, of Mark Jacobson and Mark Delucci in their studies on how modern renewables could replace fossils and supply the present global consumption. This is a traditional bottom-up approach.

After my experiences of several years in the field with different technologies, typologies, topologies, latitudes and state of development countries and confronting with the real world results, Charles Hall and myself, after having had a pint of beer in an Irish Pub in Cork commenting these issues, in the ASPO International Conference held there in 2007, decided to embark in a study on solar PV. But we tried to do it in a radically different form. It took us several years of back and forth, discussions, checks and double checks, consulting with other experts and so on.

The study, as many of you may already know, was on a real world installed plant in the best irradiated country in Europe (Spain), with the official and very accurate energy production records of the Ministry of Industry (read by telemetry to more than 40,000 digital sealed meters in each of the respective individual plants) over a period of three complete years (2009-2011). That was the main innovation: a top-down analysis and the huge scope of the solar PV plants working in the real world, rather than theoretical academic bottom-up approaches.

With more than 140 GW of installed plants worldwide, and several complete yearly cycles of operation of many of them, it is going to be increasingly difficult for some authors to continue with the academic approach, to verify real behavior of the EROI.

Now, about the energy input boundaries.

Of course, if we focus only on the energy inputs of the solar modules and their composition (glass, aluminum frame, connection box, copper or silver soldering, doping materials, silicon, ingots, wafers, cells, etc.) and perhaps inverters or metallic structures orienting and tilting the arrays, then we may come with spectacular results in a very good irradiated area with the theoretical module yield. This is what has been generally considered in most of the studies carried out to date and what is proposed by some authors as the recommended methodology.

But this is just one of the factors we looked into when we decided to analyze the energy inputs of a complete solar PV system, not just what appears in the marketing pictures of the solar plants.

After many years working in the field, one can appreciate the number of activities that are indispensable (sine qua non conditions), for a solar PV plant to work and operate as some of the authors of several EROI/LCA/EPBT studies consider they are going to work.

We differentiate some 24 factors and additional analysis that was not absolutely complete nor exhaustive, but proven and existing. None of these factors had been considered or hardly appeared in but few of the analyses made by the most renowned solar PV EROI authors. Your study of our book already identifies some of them and I have mentioned them on many occasions.

One of the factors, a7 (the energy input required for modules, inverters, trackers (if any) and metallic infrastructures, labor excluded), was precisely the EROI as usually calculated by many authors. We decided not to judge the different results of this universe of conclusions but to accept a sensible average of the range of many publications that gave us an EROI in itself for this concept of 8:1; that is, for 25 years of lifespan an Energy Pay Back Time (EPBT) of 3.1 years. Or an energy input cost equivalent to 0.125 of the total generation along the lifespan of the system.

But then we started to consider the rest of the factors (boundaries or extended energy input boundaries) and discovered that conventional EROI studies were ignoring 2/3 of energy inputs indispensable to get the solar PV plants in operation.

The list calculated the energy inputs, based on the experience of several plants in Spain and extrapolating to the 4 GW installed power studied in the book, to road accesses to the plants, foundations, canalizations, perimeter fences, evacuation lines, rights of way, O&M module washing or cleaning self consumption, security and surveillance, transportation — sometimes as far as from China, premature phase-out or un-amortized manufacturing and other equipment, insurances, fairs exhibitions, promotions or conferences (like the one you had in Stanford –to whom to attribute the involved energy expenses?), administration expenses, municipality taxes, duties and levies, cost of land rent or ownership, circumstantial labor (notary publics, public officers, civil servants, etc.) agent representative or market agent, equipment stealing or vandalism, communications, remote control and plant management, pre-inscription, inscription and registration bonds and fees as required by the authorities, electrical networks and power lines restructuring ass a consequence of the newly injected 4 GW in a national network with about 100 GW, in unexpected and not previously planned nodes of the grid, faulty modules, inverters or trackers, associated costs to the injection of intermittent loads: network stabilization associated costs (only referred to combined cycle gas fired plants, well known costs).

Some of these factors may certainly have diminished with time. Many others, have certainly increased over time. Taxes, for instance, have raised sharply. Stealing in Spain, for instance, is not relevant, but in many countries of the world it is a problem.

We mentioned and developed a little of the associated energy costs of the injection of intermittent loads, by pump up or other massive electric energy storage systems, because we knew it was going to be fundamental and relevant and did not want to open any more the old wounds in an already meager EROI. These costs are still today in a fierce debate in Spain and in many other countries, but they are certainly relevant, should the modern renewables have to replace the present fossil fueled global societal functions.

As you can see, the BOUNDARIES are of essence to determine the real life EROI, rather than an academic EROI. No one critical of our book, could say, to the best of my knowledge, that any of these briefly listed factors was not a real one and was not needed to have (at least in Spain) a solar PV system up and running along its lifetime. But for some strange reason they had never considered them.

Once they recognized the facts of real life, then this battlefield was rapidly abandoned and shifted to the “comparison” with other energy sources, namely the fossil fuel sources. Some authors were claiming that if fossil fuels were treated with these ‘extended’ energy input boundaries and factors, their EROIs should obviously go down in a similar proportion.

What they did, then, was to use a multiplying factor on the order of 3 for solar PV, arguing that it has a logic, when comparing equivalent systems and using an equivalent methodology. I fully disagree and I have shown in several occasions the reason why:

The world uses (mostly burns) about 13 BToe/year of primary energy or more than 510 EJ/year.

Of that, approximately 170 EJ of fossil + nuclear go to produce an equivalent of 40 EJ of clean and useful electricity, this making the point of Raugei valid to some extent, if the solar PV systems would entirely go to replace electricity produced by fossil fuels, because of the losses of about 2/3 of the primary energy in the conversion process.

But the world is not behaving in this way, as scientists like Raugei and Fthenakis must know. New renewables just enter into the energy equation to simply provide more energy to the global system.

Above all, the most important flaw in this assumption is that the world also consumes about 285 EJ in non-electrical uses, like aviation, civil works, mining, transportation, merchant fleets, armies or agriculture (eating fossil fuels, Dale Allen Pfeiffer). And it happens that if we would pretend to use electricity from renewables to replace the fossil fuels used for these global activities, likely through an energy carrier like the eternal hydrogen promise, the pretended multiplication factor used by Carbajales et. al, would immediately operate in the reverse form and become a division factor, probably in the order of 3, with respect to the direct use of fossil fuels of today. That is why we did not employ this “correction factor” used by Carbajales et al.

I will not enter into this debate further, because I find it futile. I do not care if when treating the EROI of coal, oil or gas with these extended boundaries may go down 2/3 from already published studies, now ranging with the old methodologies, for instance, from 100 to 12:1 for oil, depending on the period and places, or 60 to 20:1 or coal or gas in similar levels.

Taking down these 2/3 of present EROI studies will not change the fact that this society is now moving itself with fossils in an 80%. And makes it possible to move it. This is the final proof. And an important part of the rest (excluding perhaps a part of biomass in underdeveloped countries) is also being produced because the energy subsidies given by fossil fuels to the other sources, like nuclear, or hydro, that we could not have dreamt of having them, if a well endowed fossil fueled society and its related machinery and technology wouldn’t have been available. Nuclear, hydro, solar PV, solar thermal or wind energies are underpinned (or absolutely underpinned) by a fossil fueled society, not the vice versa. The global society has been making its growing economic, industrial and technological life basically without those energy sources. But we could not imagine these sources working and feeding themselves in all the complex value chain, and besides giving an important net energy surplus to the global society. Not now, neither in a foreseeable horizon.

That is, we can not ignore this crucial fact: biomass helped initially to coal to develop, but 60 years from the first massive use of coal, this fossil fuel had already passed biomass in volume and versatility of use and became quite independent of biomass.

This happened circa 1900, at the level of 800 MToe/year of global primary energy consumption and with about 1.6 billion inhabitants.

Then came oil, much more dense and versatile than coal. It took oil again about 60-70 years to pass coal and biomass as the main global energy source. This happened circa 1960, but then, in a consumption level of 3,000 MToe/year and with 3 billion people on Earth.

Now, we move in the level of 13,000 Mtoe/year of global primary energy consumption and with about 7.2 billion people. But gas or nuclear have not passed oil as the prime energy source. And we have to wonder why, if they were discovered and tried to be used massively more than 60 years ago.

Quite the contrary, we are moving fast, because of peak oil, back to the possibility of coal surpassing oil again in a decade or so, as the main energy contributor, but this time, probably at a lower global consumption level and probably with a world population still growing in numbers and in poverty.

The first two big energy transitions (biomass to coal and coal to oil) were made with the surpassed energy source still growing and helping to initially boost the coming one, but soon proved to be quite self sufficient to feed a growing and demanding global society, well after paying for their own energy inputs in the exploration, mining or drilling, extraction, transporting, refining and distributions processes WITHOUT ANY DOUBT, because nobody will doubt the evolution of the last century and the role of the fossil fuels on it. Now, we have to face the third big energy transition, in the highest level of energy consumption and population and with the main energy fuel, oil, in depletion.

Of course, one has to accept that in this complex world, all energy sources are somehow interrelated, but, as Orwell said in The Animal Farm, ‘all animals are equal, but some animals are more equal than others’. This is exactly what is happening with the energy sources and its properties and qualities: they can all be measured in EJ or in TWh or whatever, but some are more equal than others. Meaning that there is an obvious ASYMMETRIC interdependence of energy sources, being in the last century, the fossil fuels (and oil in a very first place), the ones responsible for our present global status.

To me, then, there is a non sequitur to shift the EROI battlefield to try to extend the boundaries in the fossil fuel EROI studies, to lower them and favor renewables by comparison, because whatever the EROI and the boundaries considered, it is obvious that the present global society spending 13 BToe/year of primary energy (80% of them from fossils), has been able in the last century (we shall see for how long) to pay their own energy expenses, and BESIDES putting a huge net energy surplus at the disposal of 7.2 billion humans and keep growing in a spectacular form for more than a century.

For instance, when the IAE mentions in their WEOs the costs of ‘subsidies’ to different energy sources, it always calculates much bigger subsidies for fossil fuels than for the modern renewables. It is a sort of energy fallacy, from my point of view.

If the global society has resources to subsidize anything, it is because it has previously gotten a surplus of resources from somewhere. And this ‘somewhere’ is obviously a global society that has created them using mainly fossil fuels at discretion. I can ‘subsidize’ my son to go to the cinema, but I cannot ‘subsidize’ myself from the salaryI  earn by myself and saved in my left pocket, by changing it to my right pocket.

I understand that some fossil fueled activities may certainly be ‘subsidized’ in certain forms. For instance, kerosene for aviation in the airports, which is tax exempted in many countries, when compared with gasoline. Or ‘subsidized’ coal prices paid to depleted coal basins in Spain to continue producing low quality brown coal, to keep the social peace in the region and avoid the miners revolting. But it is a fallacy to conclude that ‘somebody’ is ‘subsidizing’ fossil fuels globally speaking, when fossil fuels are 80% of our global activities creating surplus. From a strict energy point of view, fossil fuels are subsidizing basically the whole present world activities. Period.

What in reality the OECD watchdog does is a mystifying operation. When digging up the IEA figures of ‘subsidies’ of fossil fuels, one discovers that they are really talking about ‘prices’ or ‘price levels’ of fuel in the producing countries that are selling them domestically at prices lower than those the IEA drawn line would wish they had, to leave more ground to the big OECD importers to buy this fuel from producers at prices OECD can afford.

Coming back to the energy input expenses in extended boundaries, we also left out the financial costs, despite knowing that they were quite large and generally also a sine qua non factor. Most of the plants have been financed in an 80% of the total turnkey projects at about 10 years term, with interest, that ranged from 2% to 5% per year. I firmly believe that finance is a form of using a pre-stored available resource (in a fossil fueled society, coming from fossil fuel related activities) to erect or put in place and operate a given system. In that case, an energy system. So, when one asks for credit or leasing and has to pay back with this resource the principal and the interest to the bank, in let’s say a 10 year term, this is energy evaporating into the system through the bank.

Labor energy input costs were also left aside, even we had a very good set of data from industry in Spain, classified by categories, skills and full time and part time employees in the sector. The reason was that some of our factors may have had already included part of this labor in, to avoid some limited duplicities.

If we had included these financial (even just the additional money created and having to pay back in the form of interests by the requested credits or leasing) and labor energy input cost, the solar PV EROI would have probably plummeted to  <1:1.

In fact, it is very surprising how they criticize the methodology we used to evaluate the financial data (which they did not question basically in numbers), by stating that the conversion of monetary into energy units is not adequate and do not conform to conventional input-output methodologies. Our methodology is clear in these conversion units and reflects a quite direct relation between GDP and total primary energy spent in Spain or between active labor and energy spent per laborer or any given and specific related industrial activity or service rendered. This despite we mentioned that Spain hasn’t publish, for years, any input-output tables for the economy (Carpintero, Oscar).

However, it seems remarkable how some are incapable of detecting any anomaly in describing EPBT’s of solar systems recovering the energy spent in them in a question of few months for a life time of 30 years (EROI’s of 40:1 !!) and the astounding divorce with the economic reality, of a world or promoters that look for about 10 years economic recovery, this including heavy premium tariffs (Germany, Spain, Italy, now UK or France) or tax holidays or exemption (US and others) or economic recoveries that last more than the expected life time, if no economic incentives are given.

Without these incentives, the rest of the world is a renewables wasteland. Promoters are virtually not investing (with few exceptions in volume worldwide) in modern renewables, if there are no such incentives. The 140 GW world installed base so certifies, with about 70% of the global installed base made in developed countries with incentive schemes and some 25% made by emerging countries, like China or India (now Brazil or South Africa in a much lesser amounts), also with strong political incentives to cope world markets, leaving a meager 5% for the rest of the world. Doesn’t this crude reality shows anything in their conversion of monetary units to energy units methodologies, to the ones giving EPBTs of few months and financial recoveries of many years?

So, I am not surprised, Alice, that some experts, having in their records tens of papers published with high solar PV EROI results, would have shown some annoyance at your question on our book. I would humbly ask from here that when somebody mentions that we work with some methodological ‘inconsistencies’, -a term to which they are so fond of to disqualify other disturbing views- they should rather look into the above explanations and facts of the real world.

I have kept silent until now on what I consider a very regrettable behavior now made public by Raugei, as per your comments. It is true that they dared to write our publisher asking him to stop publishing the book when it was in a draft version in a sort of censorship I had not seen since several centuries in medieval Spain. The recommendation came after somebody took the draft from our publisher without our consent some time before the release and they tried to stop the publication, even threatening that they would discredit it, as they have been doing since it was published, if it were published.  I have never seen such a type of behavior, even less in the academic instances.

The reason they gave first is that we missed our final EROI (2-3:1 being quite conservative and I reaffirm myself more and more as years are passing) by an order of 3. That was precisely the Raugei view on the penalty to be imposed on fossil fuels, if a clean electricity source could replace every kWh of fossil fuel origin, considering that in conventional fossil fuel (or nuclear plants for the case) we need about 3 units of primary energy to get out 1 unit of electric energy. We tried to clarify this in some posts, but unsuccessfully.

Fortunately, the publisher did not consider this a direct threat and the book was finally published.

As for the Raugei comment that the book was ‘awful’ because it had not been ‘peer reviewed’, he qualifies himself. Just look at the acknowledgements of the book. Two professors in Physics from different universities did review the book and produce sensible comments. Charles Hall, the coauthor, is an institution in EROI, that is here questioned with superficial comments. Besides, I understand that publishing a book is a free decision, that does not necessarily require peer revisions, yet despite that, we did have our work reviewed. Perhaps what Raugei wanted to say is that the peer review was not made by the usual reviewers in an endogamis game.

I have been observing that in the academic world, things are getting unfortunately tougher. Some of the technical papers have sometimes more pages of references than pages of content (see more of my comments on the article below). In the case of solar PV systems, and the references in published papers, it seems there is an excess of ‘selfies’ which were a fashion in the academic papers, much before than with the smart phones and the sticks. And secondly, it appears that credits are gained or given by the number of references that a given person is quoted and this has started a race for a sort of endogamic cross-quotations, that gives all the reason to Tadeusz Patzek, when he talks about the ‘Sovietization’ of the American science. Perhaps what disturbed Raugei about our book is that we also skipped somehow from these habits and did not leave to the usual teams a review that, with all probability, would have ended in the basket.

Of course, Raugei is right when he presumes that our case is perhaps valid for Spain and for the 4 GW installed within the period 2009-2011. Because should we had considered Germany and its public production of solar PV systems within the same period, the Energy Return in terms of MWh per MWp installed would have been less than half of those of Spain.

I am now retired and happily growing my organic farm. Not now or since 2001, when I left working for a telecom corporation, have I had any interest in discrediting or crediting solar PV systems. I am not making my life by publishing papers and trying to gain credibility on a given subject. If anything, I should have defended, as you very well stated, the solar PV systems, because I own 50 kW within a 1 MW plant that I manage and I have helped to design, develop and done some consulting (including what we call here ‘permisología’ (an intricate paperwork to get all permits and licenses to the the solar PV plants) of more than 30 MW that are working with different technologies, typologies, and topologies in different latitudes in Spain. I have also cooperated with projects in some Latin American and African countries and I have worked as director of Development of Alternative Energies for a listed Spanish company for a couple of years within the period.

Just a final nota bene, with additional comments on the paper Energy return on investment (EROI) of solar PV: an attempt at reconciliation. Michael Carbajales-Dale, Marco Raugei, Vasilis Fthenakis, Charles Banhart Journal of Latex Class Files. Volume 11 No. 4 December 2012

1) http://www.researchgate.net/profile/Michael_Carbajales-Dale

2) select the thumbnail picture on the left and then download

I can’t get the link provided to work, but maybe it’s my computer settings: http://www.researchgate.net/publication/271699871_Energy_return_on_investment_%28EROI%29_of_solar_PV_an_attempt_at_reconciliation:

The title of this paper, is a supposed attempt to reconcile different views on solar PV EROI, but I have never been informed by the authors of it, even though I have the dubious honor of being cited several times in it.

I did not know that I had formed a so called “Prieto group in Madrid ”, in second place, after Fthenakis group in Brookhaven and before Weissbach group in Berlin or Brandt group in Stanford.

Also surprising is that the document is dated in December 2012 and our book was not published until the spring of 2013. Even more surprising, that the book is mentioned several times, to be criticized, but it does not appear as such (Prieto & Hall. Spain’s Photovoltaic Revolution. The energy Return on Investment”. Springer, 2013) in the bulky references, that occupy almost as much space as the article in itself. It appears, however, as some uncertain (P. Prieto and C. Hall, “Eroi of spain ’s solar electricity system,” 2012). This does not seem to be a very edifying example in referencing others.

Then, the paper comments that “an average energy payback time (EPBT) of 3 years and lifetime of 25 years are used to calculate the EROI subscript PE-eq = 8.33 value for this part of the system. No references are given for any other input data; though it appears that anecdotal worst cases of installations were generalized by the authors”.

Well, a brief look to the a7 factor (page 78) of Energy derived from Conventional Life Cycle Analysis Studies and Calculated as an Inverse Factor of EPBT”, comes out with an EROI of 8:1 for the energy content in modules, inverters, trackers and metallic infrastructure, quotes some works of Fthenakis, Alsema and Kim among others not cited, not to make too boring the EROI publications ranging around 8:1 in their conclusions and with these parameters analyzed (without extended energy input boundaries). Some more could be found in many places. In fact, these levels of EROI for solar PV were quite common in the early years of 21st century. See, for instance, Bankier and Gale in its Energy Payback of Roof Mounted Photovoltaic Cells. Energy Bulletin. June 16. 2006, where they come out with a number of EROI’s ranging from EPBT’s from 1 year (EROI 25:1) to 25 years (EROI = 1:1)

Author Low Estimate (years) Low Estimate Key Assumptions High Estimate (years) High Estimate Key Assumptions
Alsema (2000). 2.5 Roof mounted thin film module 3.1 Roof mounted mc-Si module
Alsema. & Nieuwlaar (2000) 2.6 Thin film module 3.2 mc-Si module
Battisti & Corrado (2005) 1.7 Hybrid photovoltaic / thermal module 3.8 Tilted roof, retrofitted mc-Si module
Jester (2002) 3.2 150W peak power mc-Si module 5.2 55W peak power mc-Si module
Jungbluth, N. (2005) 4 mc-Si module if emissions are not taken into account 25.5 sc-Si module if emissions are taken into account
Kato, Hibino, Komoto, Ihara, Yamamoto & Fujihara (2001) 1.1 100MW/yr a-Si, modules including BOS 2.4 10MW/yr mc-Si module including BOS
Kato, Murata & Sakuta (1997) 4 Sc-Si module. Excludes all processes required for micro-electronics industries. 15.5 sc-Si module. Includes all processes required for micro-electronics industries.
Kato, Murata & Sakuta, (1998) 1.1 a-Si module. Excludes all processes required for micro-electronics industries. 11.8 sc-Si module. Includes all processes required for micro-electronics industries.
Knapp & Jester (2001). 2.2 Production thin film module 12.1 Pre-pilot thin film module
Lewis & Keoleian (1996). 1.4 36.7 kWh/yr frameless a-Si module located in Boulder, CO 13 22.3 kWh/yr a-Si module with frame located in Detroit, MI
Meijer, Huijbregts, Schermer & Reijnders (2003). 3.5 mc-Si module 6.3 Thin-film module
Pearce & Lau (2002). 1.6 a-Si module 2.8 sc-Si module
Peharz & Dimroth (2005). 0.7 FLATCON (Fresnel-lens all-glass tandem-cell concentrator) module – 1900 kWh/(m2 yr) insolation 1.3 FLATCON (Fresnel-lens all-glass tandem-cell concentrator) module – 1000 kWh/(m2 yr) insolation
Raugei, Bargigli & Ulgiati (2005) 1.9 CdTe module including BOS 5.1 mc-Si module including BOS
Schaefer & Hagedorn (1992). 2.6 25 MWp a-Si module 7.25 2.5 MWp sc-Si module
Tripanagnostopoulos, Souliotis, Battisti & Corrado (2005). 1 Glazed Hybrid photovoltaic / thermal 4.1 Unglazed Hybrid photovoltaic / thermal
Alsema E. (2000). Energy Pay-back Time and CO2 Emissions of PV Systems. Progress in Photovoltaics: Research And Applications, 8, 17-25.
Alsema. E. Nieuwlaar, E. (2000). Energy viability of photovoltaic systems. Energy Policy, 28, 999-1010.
Battisti, R. Corrado, A. (2005). Evaluation of technical improvements of photovoltaic systems through life cycle assessment methodology. Energy, 30, 952–967.
CSIRO, Advanced Gasification Research Facility, Queensland Centre for Advanced Technologies, http://www.cat.csiro.au/3_4.htm
Jester, T. (2002). Crystalline Silicon Manufacturing Progress. Progress in Photovoltaics: Research and Applications, 10, 99–106.
Jungbluth, N. (2005). Life Cycle Assessment of Crystalline Photovoltaics in the Swiss ecoinvent Database. Progress in Photovoltaics: Research and Applications, 13, 429–446.
Kato, K. Hibino, T. Komoto, K. Ihara, S. Yamamoto, S. Fujihara, H. (2001). A life-cycle analysis on thin-film CdS/CdTe PV modules. Solar Energy Materials & Solar Cells, 67, 279-287.
Kato, K. Murata, A. Sakuta, K. (1997). An evaluation on the life cycle of photovoltaic energy system considering production energy of off-grade silicon. Solar Energy Materials and Solar Cells, 47, 95-100.
Kato, K. Murata, A. Sakuta, K. (1998). Energy Pay-back Time and Life-cycle CO2 Emission of Residential PV Power System with Silicon PV Module. Progress in Photovoltaics: Research and Applications, 6, 105-115.
Knapp, K. Jester, T. (2001). Empirical Investigation of the Energy Payback Time for Photovoltaic Modules. Solar Energy, 71, 165–172.
Lewis, G. Keoleian, G. (1996). Amorphous Silicon Photovoltaic Modules: A Life Cycle Design Case Study. National Pollution Prevention Center, School of Natural Resources and Environment, University of Michigan.
Meijer, A., Huijbregts, M., Schermer, J. Reijnders, L. (2003). Life-cycle Assessment of Photovoltaic Modules: Comparison of mc-Si, InGaP and InGaP/mc-Si Solar Modules. Progress in Photovoltaics: Research and Applications, 11, 275–287.
Odum, H. (1996). Environmental Accounting: Emergy and Environmental Decision Making. John Wiley & Sons, New York.
Pearce, J., Lau, A. (2002). Net Energy Analysis for Sustainable Energy Production from Silicon Based Solar Cells. Proceedings of Solar 2002 Sunrise on the Reliable Energy Economy June 15-20, 2002, Reno, Nevada
Peharz, G., Dimroth, F. (2005). Energy Payback Time of the High-concentration PV System FLATCON. Progress in Photovoltaics: Research and Applications, 13, 627–634.
Raugei, M. Bargigli, S. Ulgiati, S. (2005). Energy and Life Cycle Assessment of Thin Film CdTe Photovoltaic Modules. Energy and Environment Research Unit, Department of Chemistry, University of Siena, Italy.
Schaefer, H. Hagedorn G. (1992). Hidden Energy and Correlated Environmental Characteristics of P.V. Power Generation. Renewable Energy, 2, 15-166.
Tripanagnostopoulos, Y. Souliotis M. Battisti R. Corrado A. (2005). Energy, Cost and LCA Results of PV and Hybrid PV/T Solar Systems. Progress in Photovoltaics: Research and Applications, 13, 235–250.

As can be seen from the above, we were far from using as an EROI for modules+inverters, plus metallic infrastructure in a sort of anecdotal worst cases of installations generalized by the authors. On the contrary, we were more in the low estimate in years (high estimate EROI), than using worst cases.

Now, for the record, it should also be very convenient for all the prolific authors on solar PV EROI to revise the figures given in papers published several years ago, to double check how are they performing (Energy return statistics). We are very anxious and expectant to learn how it has gone with, for instance, the hybrid PV/Thermal promising analysis, or even better, the results, years after publication, of the Fresnel lenses combined with high efficiency cells in concentration mode.

I recall specifically in this respect  the V.M. Fthenakis and H.C. Kim paper, titled “Life Cycle Assessment of High-Concentration PV Systems”, in which they analyzed The estimated EPBT of the Amonix 7700 PV high concentration system with Fresnel lenses in operation at Phoenix , AZ, and found 0.9 yrs for its EPBT. I wonder if they could still support this analysis, just five years after their study and how the promising system has contributed to the grid parity worldwide, considering they recovered the energy spent on it in less than one year.

Scientific authors should be more careful when accusing to others of using ‘anecdotal worst cases’, specially for the expected Energy Return along a life time, when they are probably using ‘anecdotal best cases’, instead of going on to real life 3 years cycle proven and official statistics of production for 4 GW installed park.

Talking about the life time (directly involving the Energy Return), it is very interesting to see how some papers have changed the estimated life time of solar PV Systems from 25 years to 30 years. It is curious that virtually all manufacturers give a maximum of 25 years of power guarantee of their modules (with the corresponding degradation process over the years) and 5 years of material guarantee (the later superseding or prevailing on the former in case of failure) and we find scientists happily granting 30 years for the EROI studies. In my opinion this is a clear attempt to produce higher EROI’s and lower EPBT’s with no rational grounds.

The fact that the Carbajales et al paper ends recommending “that the conventions outlined by the EIA PV Systems Program Task 12 (Environmental, Health and Safety) be followed in conducting EROI calculations, considering that the IEA methodology has easily swallowed the 30 years life time for solar PV modules, gives us a very clear clue of what is going on with these recommendations.

In our discussions on this topic a couple of years ago, an editor came to say that if our factors were really sine qua non (indispensable) for the system to be up and running and the IEA methodology did not considered them, perhaps it was the moment to change the IEA methodology.

I would just recommend the IEA tour Spain (it is not the worst country in solar PV systems; on the contrary, it is one of the most efficient in terms of MWh produced per Mw installed). The IEA should come and check and double check how many solar PV plants have not lasted, for a variety of reasons, the 25 year life time of the manufacturers or the 30 years of the IEA backed by some scientists. Just in 2015 alone about 40 MW have been dismantled, with a lifetime averaging about 5 years. Trials are the delight of reputable and expensive law firms, which earn quite a lot of money preparing lawsuits against promoters, manufacturers, banks and the government. That is real life, far beyond the academic instances. I am following now a demand of a promoter that has decided to buy 2/7 of the modules he originally bought for his 500 kW plant, because the manufacturer (not Chinese), he originally bought from 6 years ago, has disappeared, as have most of the European manufacturers in the last 5 years. One wonders what is the value of a technical guarantee on power, if the life time of the manufacturers becomes much shorter than the one of the power of the promised modules. This is, of course, ‘anecdotal’, although not for the interests of the affected promoters.


After a couple of years from the publication, I have much more data to reaffirm for myself that we were really conservative in our 2.4:1 EROI for many different reasons and factors. But I will not publish more data. I will go back now to my organic garden and wish you all the best for what I suspect may be a grim future.

I’m a pessimist because of intelligence, but an optimist because of will. Antonio Gramsci.

Pedro in Madrid, without any group.

Ted Trainer, author of “Renewable Energy Cannot Sustain a Consumer Society” and many other great books detailing what needs to be done, wrote this thoughtful response to what I wrote about the net energy conference:

Thanks Alice for your valuable comments on the EROI of P/v issue. Yes it is very disappointing that so much confusion and acrimony surrounds this crucial issue, and that they seem not to be moving to a resolution as quickly as they should be. There are of course big interests at stake, with the conventional high EROI assumption suiting the industry, and the theorists who have previously put out such claims. At the very least Prieto and Hall should be commended for getting the whole messy issue of boundaries and components, and appropriate energy cost assumptions for the various components, on the agenda. Sadly the disputation over this issue illustrates the way scientists are not immune from prejudiced and nasty behaviour, (a considerable amount of which my efforts to analyse renewables has evoked.) As Alice notes, when large scale research funding is at stake there can be strong incentive for competitors to reinforce perspectives that suit them.

As I see it the goal should not be a single EROI figure for PV, because much depends on the situation and conditions. We need values for, for instance modules operating at the average site in Spain with its level of radiation and losses, and we need figures for the various components in the system, such as energy used to produce modules in the factory, energy used to produce the factory, energy lost in inversion, in typical inefficiency due to dust, poor alignment…, and in transmission… , energy embodied in inverter replacement, energy used to get workers to the factory, energy used for O and M at the solar farm, energy “retrieved” when the modules are recycled … A fairly thorough provision of these elements would enable anyone to work out the EROI for a particular plant at a particular location, and most importantly the EROI assuming a given set of boundary assumptions. Graham Palmer has just begun a PhD at Melbourne U intended to sort all this out

I strongly object to Raugei’s comments to you re peer review. I have little respect for the entire peer review edifice, due to my unsatisfactory experience in trying to get critical analyses published. Very often I have found the comments of reviewers to range between nit picky imposition of the way they would have expressed things or gone about the job, through reasoning that I see as at least challengeable and at times dead wrong, to rejection on utterly idiotic grounds … such as being told that my recent c 20 page detailed critique of the 2014 IPCC report on renewables was “not scientific”, after waiting seven months for review. (That phrase constituted the full case given for rejection.) On another occasion, where it took over a year to get through the difficulties, I was presented with a seven page essay disagreeing with elements in my case. If that reviewer wanted to express a different view he should have done it somewhere else, not try to insist that I say what he would have said. I have another case where possibly a c 50 word review from probably the most prestigious individual in the field said the paper was good, but the paper was rejected because a second even shorter review was unfavourable. The reasons were so unintelligible that I had to ask what they meant. It eventuated that the editor said he didn’t think it was the kind of paper his journal published … after I had waited seven months.

I see the process as far too prone to the whims, prejudices and in fact arrogance of reviewers and editors. They should get out of the way and let people say what they have found or think, and focus only on things like pointing out mistakes or pointing to overlooked evidence or assumptions, or logical errors. Their role should be to help get ideas and analyses out to others, and to block only as a last resort. Too often I have found that reviewers think their role is to make authors conform to their preferred style and they assume the right to condemn work that doesn’t proceed as they would have. I have written reviews in which I say I think the argument is wrong and the procedure not satisfactory but I think the paper should be published, because I could be mistaken and the paper does present a case that it is important for us to think about.

Ultimately what matters is not whether some guru approves of your analysis, what matters is whether the case is sound/convincing/persuasive/well supported, and that judgment should be up to readers, and the quality of the work should be established over time as others in the field comment on it. My main concern here is what must be the large amount of time and good work that doesn’t get published because of the whims of some guru. I would assume that most of us have had papers rejected by one set of reviewers but regarded highly by those from another journal.

So I see any attempt to block publication of controversial, and even flimsy/challengeable cases, on grounds to do with “peer review” as very annoying. I have no interest in whether or not it was peer reviewed; what matters is whether or not the case it argues is sound, or valuable, or ought to be heard. (Theses that are dead wrong can turn out to be valuable contributions, by helping subsequent discussion to clarify an issue.)Whether or not it was peer reviewed has nothing to do with whether or not it is correct, or a valuable contribution, and, Alice, should certainly not be regarded as “a valid criticism” .

In my view Raugei raises some important problems, such as the effect on the Pietro and Hall conclusions had by the Spanish subsidy system, but it’s appropriate to now sort these, not to regard them as reasons why the gook should be rejected. The most important issue he raises is in claiming that the energy input to PV production should be reduced to one-third, on he grounds that it is electricity and PV produces electricity. As I see it this simply depends on whether the electricity used to produce the modules is coming from PV (or wind or CSP) generating systems … and at present it isn’t. In a world where all electricity came from PV farms it would make sense to put the value of the electricity input into the denominator of an EROI, but in the presenter world the energy going into production is (mostly) coal.
Endnote: This book was only available online at the University of California. It’s a shame libraries are putting many journals and books into electronic versions only.  Especially this book.  Microchips, motherboards, and computers will be among the first casualties of declining fossil fuels, because they have the most complex supply chains with many single points of failure, dependence on rare metals, and so on (see Peak Resources and the Preservation of Knowledge for details). I encourage you to get your (university) library to buy a hard copy of this book, so that future scientists and historians will understand why our society didn’t replace fossil fuels with “renewables” even though we knew oil couldn’t last forever.

On an energy form, Prieto recently wrote (March 2014): “Since we wrote the book, I have been able to experience a few more incidental factors: mice delightfully gnawing the cables and covers and optical fiber communication color cables, and storks excreting on modules with about 6 inches size -one cell- per excretion. Real life has many factors that they are not accounted in organized studies in labs, universities with particular technologies and plants in perfect irradiation places.”


Bankier, C.; Gale, S. Energy payback of roof mounted photovoltaic cells. The Env. Eng. 2006, 7, 11-14.

Bullis, K. 26 Aug 2010. Self-Cleaning Solar Panels A technology intended for Mars missions may find use on solar installations in the deserts on Earth. MIT Technology Review.

Colthorpe, Andy. 18 July 2013. Solar Shakeout: Spain’s Cel Celis begins insolvency proceedings   PVTech.

Fthenakis, V.H.C. et al. 2011. Life cycle inventories and life cycle assessment of   photovoltaic systems. International Energy US Energy Investment Agency (IEA) PVPS Task 12, Report T12-02:2011. Accessed 19 Sep 2012.

Neubacher, A. January 18, 2012. Solar Subsidy Sinkhole: Re-Evaluating Germany’s Blind Faith in the Sun. Der Spiegel.

Nikiforuk,Andrew. 1 May 2013. Solar Dreams, Spanish Realities. TheTyee.ca

Parnell, John. 22 July 2013. Spain’s government accused of killing solar market. PVtech.

Parnell, John. 23 July 2013. Spanish government facing court action over cuts to solar support. PVTech.

Pentland, W. Nov 30, 2015. Spain’s Renewable Energy Powerhouse Abengoa Teeters Toward Bankruptcy. Forbes.

Raugei M., et al., “The energy return on energy investment (EROI) of photovoltaics: Methodology and comparisons with fossil fuel life cycles.” Energy Policy (2012), published on line doi:10.1016/j.enpol.2012.03.00897.  See more at: http://www.todaysengineer.org/2013/Jun/book-review.asp#sthash.YsRjuI9R.dpuf

Prieto & Hall, 15 Apr 2011. How Much Net Energy does Spain’s solar PV program deliver?  A Case Study.  State University of New York 3rd Biophysical Economics Conference.  Data sources for Energy Generated and Energy Invested slide 10, How monetary costs were converted to energy units.  Slide 12, How the embodied energy costs and boundaries were determined  Slides 17, and much more.

Soble, J. March 3, 2015. Japan’s Growth in Solar Power Falters as Utilities Balk. New York Times.

Spanish solar energy: A model for the future? Phys.org


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26 Responses to Tilting at Windmills, Spain’s disastrous attempt to replace fossil fuels with Solar Photovoltaics

  1. xraymike79 says:

    Can I re-blog this post with the link back to you?

  2. Gingerbaker says:

    So, let me get this straight. Even calculated with the most pessimistic interpretation, Spain’s solar project shows a positive ROI. And you say this is “disasterous”?!?

    Meanwhile, as more and more renewable energy is deployed across the world, all of those pessimistic calculations will have to be updated, and with each update, the ROI will only improve.

    Since we are at the near zenith of our renewable energy trajectory, the future looks quite rosy indeed. What industrial processes could not replace fossil fuels with electricity? Is the answer not, in fact, virtually none of them?

    • energyskeptic says:

      Please read the energy section of this website and some of the books in my booklist on this topic (i.e. Hayden’s “The Solar Fraud”, etc. The answer to your question is not a soundbite, tweets and columns can never fill in the knowledge gained by reading peer-reviewed articles from the top science journals, and books, there’s no short-cut to a “Big Picture View”.

  3. David Archibald says:

    Has someone determined what PV power would cost if power from PV was used to make the whole installation? I understand that currently it is mostly coal-based power that is making them at perhaps $0.04 per kWh. The PV installations then produce power at a cost of $0.20 per kWh. It looks like the price of PV power would be infinite. One day the coal will run out.

  4. yt75 says:

    Thanks a lot for this review, I knew about Pedro evaluations but didn’t know about the book!

  5. Marco Raugei says:

    I find it rather unfortunate that my personal comments to Ms. Friedemann about the book by Prieto and Hall were misconstrued as stemming from the frustration at a failed attempt at “medieval censorship”.

    To try and clarify once again:

    the main issue with Prieto and Hall’s book, apart from the somewhat crude nature of their money-to-energy conversions, is that their analysis was promoted and advertised as reporting on “the true EROI of PV” (largely understood as that of the technology itself, to be then liberally compared to that of “oil” or “coal” as alternative energy sources),

    instead of something like “the societal EROI of PV in Spain, in the specific circumstances dictated by the incentives and deployment schemes in place that country in 2009-11, and including all the documented (yet often in principle avoidable) system-level inefficiencies, as well as a host of monetary inputs used to indirectly support the PV industry in its early stages of expansion, etc. etc.”.

    As to Mr. Prieto’s response of 11 April, I have no problem in conceding that there is some truth in many of the points he makes.

    However, the main issue there is, again, that of a loose definition of goal and scope.
    In fact, by reading through his long post, it appears that Mr. Prieto’s ultimate interest lies not in comparing PVs to e.g. coal- or oil-fired electricity production systems, but instead in comparing the ability of PV to completely replace fossil fuels by single-handedly supporting all of society’s energy demands.

    I personally wonder whether it is even reasonable to frame the problem in these terms – but even if one were to accept this as the starting point for one’s analysis, the fact remains that one would then have to be extremely cautious in the way the latter is carried out and advertised, in order to:

    (i) avoid a somewhat random (and hence yes, inconsistent) cherry-picking of the energy inputs, and, even more importantly,

    (ii) prevent the subsequent inadvertent (or even worse, intentional) extrapolation of the results to a different context from the one for which they were intended.

  6. Charles Hall says:

    There are many things I could say, but mostly hooray to Alice for bringing this up again in her marvelous fashion! And to Pedro for his exhaustive replies, many of which show how conservative our initial assessments were. Of course our analyses were for one country at one time. OK lets see such an empirical study done elsewhere and with boundaries that include ALL the necessary inputs. The reader should know that both Weissbach and Graham Palmer have published studies that are comprehensive and give results similar to ours.
    One thing I find amazing is that no one mentions the sensitivity analysis Pedro and I did in chapter 7. This covers the special effects of the Spanish situation, weighting electricity vs fossil energy, removing financial services from the assessment or considering an energy assessment of labor. None of them, other than the obvious effect of multiplying the electrical output by three or including the energy to support labor’s paycheck, made any very large difference in the EROI. There are other sensitivity analyses here and there in the book. Why in the world do people criticize us for things we had already examined and published the effect of? Did they read the book?
    The boundaries issue remains critical and I for one will not believe any EROI that does not have something like as thorough as we have attempted in our book. All that we do is enormously subsidized by fossil fuels, and we need to understand that better. I hope that we will someday have a better estimate of the energy cost of indirect costs, business expenses, roads etc. but leaving them out completely is, in my opinion, a greater error than using a value that has uncertainty, especially when that uncertainty is examined. In the 1970s we had some fair idea of the energy costs of all kinds of goods and services in society due to the wonderful work of Bullard, Hannon and Herendeen using detailed I-O tables and good government data, with uncertainty analysis. Services were quite energy intensive, although not as much per dollar as most goods. Now there are no such analyses and government energy use data sources degrade year by year. So we used and corrected these old values and compared and corrected them against what we could come up with for these issues today. All explained in the book.
    Most of the uncertainties in EROI are greatly reduced when goals and boundaries are consistent, when an explicit methodology is used (e.g. Murphy et al. 2011, Order from Chaos, a preliminary protocol…in Sustainability) and when real data, not cherry picked lab data, is used. I look forward to better science in the future, but the failure of the Stanford meeting to answer Alice’s spot on question, and the ascendency of neoclassic economics vs using as hard real science as we can bring to bear, does not leave me with too much hope.

    • Marco Raugei says:

      Just a couple of quick comments:

      1) Indeed, the authors are to be commended for the inclusion of a sensitivity analysis in Chapter 7 of the book. Alas, this does not appear to have prevented many (including Ms. Friedemann) from liberally (and unjustifiably) extrapolating a simplistic “EROI=2” mantra tout court.

      2) Weissbach et al.’s paper is hardly worthy of being used in support of anyone’s findings, since it is fraught with methodological sloppiness, and has in fact been the object of two detailed (and, of course, peer-reviewed) rebuttals:


    • Tom S says:

      Hello Dr Hall,

      First let me commend you for such a detailed analysis as you presented in your book. Many of the factors which you included (such as dust on panels, module mismatch, etc) have been omitted from previous analyses of energy returns, and should be included.

      However, I think you are making several mistakes in your analysis, as follows.

      First, your formula for converting money into energy is mistaken, in my opinion. If you divide the average energy intensiveness of the economy by the GDP, then you are getting a factor of energy consumption, not energy investment. For example, in your presentation HOW MUCH NET ENERGY DOES THE SPAIN’S SOLAR PV PROGRAM DELIVER? A CASE STUDY which is referenced at the bottom of this article. On pp 12, you indicate “At 1 Toe = 42 GJ, this represents 5.12MJ/Euro” however that is the amount of energy consumption in the economy. The vast majority of the energy used in the economy is consumption, not investment to obtain more energy. Energy consumption should definitely not count as energy investment. To obtain the energy investment, you must divide that figure by ERoEI which prevails in the economy as a whole. This adjustment alone increases your reported EROI from 2.79 to 5.22.

      Second, you do not include embedded energy which is recovered when solar modules and frames are dismantled and the aluminum used to manufacture them is recycled. The studies you cited do not include this important factor. If embedded energy is counted on the way in, it must also be counted on the way out. Of course, there is some energy loss when aluminum is recycled (it takes 25% of the energy to use recycled aluminum as raw) and that should be accounted for.

      Third, you are assuming that the lifespan of a typical cell is equal to its warranty. This seems unlikely to me. Although some cells will fail before the typical warranty expires, most of them will last longer, which is why manufacturers warrant them for that period. If the typical warranty is 25 years then we should assume that the typical cell lifetime is at least 30.

      Fourth, even if you assume that the cell period is equal to the warranty period, the lifespan of everything else you include at the plant (roads, metal fence posts, cement, foundations, etc) certainly won’t fail exactly on the warranty date of the cells. Those things could be re-used. I think those things should be given a lifespan of at least 50 years.

      Finally, you are citing ERoEI studies which refer to outdated methods for manufacturing PV grade silicon. Those studies are referring to the Siemens process. Other processes invented more recently can be used which produce PV grade silicon at only 40% of the energy cost. This is a large factor in the EROI of PV. We should use only the most recent methods because we wish to find the EROI of PV going forward, not the EROI of PV in the past.

      -Tom S

      • energyskeptic says:

        Tom, I see you have a website “BountifulEnergy Debunks the arguments of energy decline theorists, peak oil doomers, and others. Argues that energy is abundant.” Dr Hall doesn’t read my website very often so I doubt he’ll see this. I think your argument would be more convincing if you could find some peer-reviewed papers. If you read the book you’ll see that Prieto and Hall conclude that even if solar panels are 100% efficient the maximum EROI is 3.6 because there are still all the other factors besides the panels themselves that lower EROI, and Prieto’s comments indicate they could have made the case that the EROI is negative. Since freight transportation can’t be electrified, and runs almost entirely on fossil fuels, solar EROI doesn’t matter, electricity doesn’t do much good.

        • Tom S says:

          Hi Alice,

          “I think your argument would be more convincing if you could find some peer-reviewed papers.”

          Hall’s book was not peer-reviewed either.

          “If you read the book you’ll see that Prieto and Hall conclude that even if solar panels are 100% efficient the maximum EROI is 3.6 because there are still all the other factors besides the panels themselves that lower ERO”

          You are just re-stating their conclusion here, without correcting there errors I pointed out or responding to the objections I raised. If you correct the errors I pointed out, then the EROI is much higher than 3.6.

          “Since freight transportation can’t be electrified, and runs almost entirely on fossil fuels, solar EROI doesn’t matter, electricity doesn’t do much good.”

          Freight transportation could easily run off gas. If most gas which is now used for generating electricity were freed up for transportation instead, it would buy a lot of time for the development of alternatives.

          It’s also worth nothing that almost half of rail traffic in the world now uses electricity from overhead wires. So it is possible to electrify frieght transportation to a large extent.

          Also, many ships have been built which used coal as fuel in steam turbines. If the electric generating infrastructure were converted to renewables then much coal would be freed up for that purpose.

          -Tom S

    • Tom S says:

      Incidentally, I’ve performed the adjustments I suggested above, and I obtained an EROI of 6.27 for solar PV in Spain. This includes all the factors which you included, like dust on panels, transportation of the modules, taxes, fairs, exhibitions, accountants, and so on. I just used your data and performed adjustments as suggested above.

      -Tom S

    • Tom S says:

      One more thing: I added a post to my blog about precisely these issues, here:


      I would be delighted if anyone finds any errors in my analysis.

      -Tom S

  7. Massimo Ippolito says:

    Finally I’m happy about the Prieto admission of inaccuracy, in the direction of PV optimism, of the figures of his works.
    The worst problem with Pedro Prieto and Charles Hall is that they have established a lower bound ERoEI for PV in literature,
    sterilizing any doubt about the level of effectiveness or harmfulness of the policies promoting PV.
    If somebody, i.e. a concerned citizen in a internet group, argues that the PV ERoEI is much lower than expected, and is also lower than 2.4, this is the immediate occasion to start a flame with incredible emotive and bad reactions and insults.
    The Prieto-Hall, Weissbach works are often cited as reference for the most pessimistic figures available on PV, and “even a little ERoEI is better than nothing” is the sentence that closes the discussion by the zealots of PV.
    Then the poor who just did the math has to come back to check his data-set and his computations, but unfortunately the result remains unchanged with a systemic ERoEI of PV around 0.x.
    Systemic ERoEI means that it is computed on the comprehensive Life Cycle Assessment of the technology focusing on the societal advantage.

    Underestimating the ERoEI threshold means being directly responsible for worsening the climate change issue and economy due the lack availability of cheap energy.

    I’ve read that Gail Tverberg refuses to consider ERoEI as an enlightening factor anymore, because this very important parameter doesn’t have a standard and each faction adopts different flavors to support its own ideology.
    It is a pity, because this is a very simple and straightforward evaluation method to suggest the right policies in energy domain.

    Those who are used to do the math in order to both understand the main issues or solve professional problems, are also used to look for a sort of “9 proof” (casting out nines) to assess the results.
    We think we have found a proof with a scientific dignity, which is linked to the energy intensities of the countries, and which represents the rational and unavoidable bridge between money and energy.

    Italy is the most virtuous country and has an energy intensity of 2kWh each $ of GDP.
    This means that each Italian has to burn 2kWh for each $ earned.

    China is 4kWh/$ and Asian “tigers” are at 8kWh/$.

    Ken Caldeira (2) well explained why Italy and Europe as well as USA become virtuous:


    The reasons are the emissions embodied in trade as shown up in his studies and it is the same reason why Europe shutdown all the PV manufacturing facilities as aluminum smelting and steel production.
    in fact we delegated to China the energy intense productions.(2)

    We know that most of the PV in 2014 was installed in ASEAN, which an energy intensity of 4 – 8 kWh/$.
    The total investment on PV in 2014 has been 148billions$. (1)
    This means that ASEAN countries have invested 600-1200 TWh, mostly in coal energy to manufacture and install the 2014 46GWp PV. (1)

    Then the PV owners have to spend 2% – 3% of the investment each year for PV maintenance.
    …300 – 600 TWh more of coal/oil to burn to support that activity.

    Then Chinese taxpayer have to collect 50$ each MWh produced by the PV per 20 years in order to subsidize it with the FiT, (Italians over 250$)(3)
    …and this are other 184 – 368 TWh of dirty energy.

    Sunteck was the major example of bankruptcy with billions of: bailouts, refinancing, capital increasing, all this weighting about 60 billion/year (1) mainly in solar sector.
    …and other 240 – 480 TWh.

    The grid balancing cost as well explained in Weissback paper is an other important issue. In the Italian experience this reaches an amount comparable to the FiT (3)
    so I guess other 184 – 368 TWh (much less than Italian case) as PV energetic cost quota to protect the grid from the intermittent source.

    Most of the PV plants are installed on land-fields, thus annihilating almost 1W/sqm of photosynthesis.
    The typical figure of territorial power density for PV is 4 W/sqm (5-6 mcSI, 2-3 thin film) .
    This implies that the 25% of the PV production only restore energetically the missing photosynthesis production.


    This means between 1500 – 3000 TWh of burned fossil energy to implement and lifelong manage 2014 PV facilities that may supply optimistically 1000 TWh in 30 years.
    This figures automatically downgrade PV from renewable source to mere energy vector.

    And we didn’t consider the decommissioning activities, the insurance costs in case of plant damages and the financial rates.
    So the ERoEI is clearly under the unit, and the past figures are worst and the future ones too, we currently assist a dumping effect.
    Another derogation, in this analysis in favor of PV, is that the energy intensity of the PV sector is much higher than the mere country figure.

    1) http://fs-unep-centre.org/sites/default/files/attachments/key_messages.pdf
    2) http://www.pnas.org/content/107/12/5687.figures-only
    3) http://www.brunoleoni.it/nextpage.aspx?codice=11679

    I think that Raugei has to look for a reconciliation of his ERoEI with those figures without bothering with the “crude nature of money energy conversions” .
    I’m professionally in the industrial side of energy and I’ve also learned to consider with circumspection papers and the peer review process.
    We often host many Phd student in internship and they admit to adapt their papers or master works to ideological belief of their academic tutors


  8. I don’t have the time to go over the details of the editorial above so I will limit my response to three basic items:
    1. My name (Vasilis Fthenakis) was cited above as having published estimates or EPBT and EROEI based on models, not actual data and that my estimates include only modules, not the rest of the system. Alice, you got it completely wrong; if you bother to look at my peer-reviewed journal articles (and Yes I believe in peer-review) you will see that my estimates (also consensus estimates from IEA PVPS Task 12 comprising LCA analysts from 12 countries and 2 industry associations) are all based on actual process data; data that originate in 13 different manufacturing facilities in the EU and the US and were cross-referenced and verified exhaustibly.
    2. It is true that we describe, quantitatively in great detail, the best actual systems of which there are min-to-min and hourly performance data over many years and we don’t bother with the worst. We do this because only the best survive, and yesterday’s best is proven to be today’s average. All the ground-mount utility PV systems in the US that were constructed since 2010 and are being operated accordingly. The fact that the system prices for c-Si and CdTe PV fixed tilt and 1-axis tracking have gone down a factor of 3 since the timing of Pietro’s experiences is a clear indication of the continuing evolution taking place which we have been accurately described and quantified.
    3. I also thought that presenting Pietro’s book as a book describing the global PV reality was a disservice and for the two years before the publication of the book I tried to engage the authors asking for their data which they were not providing. And yes I complained to the publisher about this lack of scrutiny to literarily promoting one’s view as the view for the world and hinder the growth of solar.
    Vasilis Fthenakis, PhD, senior chemical engineer (with tenure) Brookhaven National Laboratory and professor of earth and environmental engineering, Columbia University
    author or co-author of 300 articles and 4 books on topics at the interface of energy and the environment (email: vmf@bnl.gov)

  9. I want to add to the 1st item above that our estimates of EPBT (and by extension EROEI) are based on energy and material burdens in the life-cycle of the modules, mounting structures, inverters, transformers, cables, thus of the whole system till the high-voltage feed into the substation. All based on actual-process data. To the reader: if you have the time and the interest please read our publications; some of them have been cited 300 times in journal articles of others -they must be credible
    Vasilis Fthenakis

  10. Pingback: OTRA VUELTA DE TUERCA A LA TRE FOTOVOLTAICA | Crisis Energética

  11. Massimo Ippolito (and also Prieto and Hall),

    The idea that financial input can be converted to energy input is simply wrong. It’s like claiming that the cost of a car should be a factor in calculating its fuel efficiency!

    GDP increase and money creation are two completely different things, and the latter leads the former. The former is likely to increase energy use, but it is not proportional to energy use. Whereas money creation occurs when money is borrowed into existence, though an equal amount of debt is created so that it sums to zero. When the money is spent it becomes part of GDP. But if you’re tracking the energy cost of what it gets spent on, it would be double counting to then assign the average energy cost to the money spent.

    And the idea that an EROI of 12 or 13 is needed to run a complex civilization like ours is ludicrous. Looking at countries’ EROI figures and using them as a basis of a claimed requirement is like looking at their road systems and saying a speed limit of at least 60MPH is needed to run a complex civilization like ours! A higher speed limit may be advantageous but it is not a prerequisite, and a complex civilisation like ours would still function if the speed limit were lower.

    There is no possible mechanism for an EROI of 12 or 13 to be a limiting factor. Likewise with a figure of 7 (which I’ve seen quoted elsewhere). The energy cost can be a limiting factor, but the more advanced a society gets, the more this depends on the value of human work rather than energy inputs. And suitable land can be a limiting factor. But as long as net energy is positive, EROI can not be because (in the absence of some other limiting factor) the problem can be solved with more energy infrastructure.

  12. Thank you Aidan, for reminding us that Mr. Prieto directly converted financial inputs to energy burdens in his EROI calculations. Economic Input/ Output (EI/O) is only valid when done within narrow data categories and only for comparison purposes. Mr. Prieto converted business air-fares for solar consultants travelling in/out Spain to the energy burden for installations in the country! This type of “energetic expense” is never accounted for in Life-Cycle Assessments of competitive power sources (e.g., coal, oil, nat. gas, nuclear) and show how unbalanced and consequently wrong, Mr. Prieto’s estimates are.
    Vasilis Fthenakis

  13. Pingback: Elon Musk’s New Battery Will (Not) Save The World From Itself | LiamScheff.com

    • energyskeptic says:

      The whole point of having battery backup is for when the electric grid is down, which it increasingly will be. But to do that, you need a generator to keep the battery at least 20% charged, or the battery life will be greatly shortened. Maybe the top 10% can afford solar, battery, and generator now – after another financial crash less than that, because credit will vanish. But why would you do this in the first place? My friends who live off the grid and have all these things use their solar panels only for lighting! They spent $20,000 and the backup batteries aren’t powerful enough to run a refrigerator, stove, microwave, and so on.

  14. Robert Wise says:

    Thanks for reviewing this book, which I can’t afford to buy. I didn’t get through the entire review, but I believe I got the gist of yours and Pietro’s comments.

  15. John M. Morgan says:

    Sorry if I am being dense, but when you say:

    “Spain’s solar photovoltaic electricity . . .
    “Solar PV would have to cover 2,300 square miles to replace the energy of nuclear and fossil fuel plants. You’d also need the equivalent of 300 billion car batteries to store power for night-time consumers.”

    Do you mean in Spain or on earth?

    • energyskeptic says:

      In Andrew Nikiforuk’s “Solar Dreams, Spanish Realities” in TheTyee.ca Prieto was interviewed:

      “But the big issue for solar is simply scaling up the enterprise to capture enough of the sun’s rays to retire just a fraction of fossil fuels. Prieto calculates, for example, that to replace all electricity made by nuclear and fossil fuels in Spain would take a solar module complex covering 6,000 sq. km of the country at the cost the entire Spanish budget (1.2 billion Euros in 2007). It would also require the equivalent of 300 billion car batteries to store the energy for night-time use.”

      As far as storage goes, the article also says this: “Storage: Solar power offers intermittent bursts of energy, posing storage challenges. The average percentage of time a solar operation pours electricity onto the grid at full rated capacity ranges from 12 to 19 per cent. In contrast a coal-fired plant runs 70 to 90 per cent of the time. Storing sun-derived power in batteries, molten salts or compressed air schemes remains problematic if not costly due to significant energy losses in storage and release.”
      And has some interesting concerns about materials: “The making of solar photovoltaic cells requires rare elements such as gallium, tellurium, indium and selenium. Called “hitchhiker” metals, most are the byproduct of industrial copper, zinc or lead production. New thin-film solar sheets, for example, depend on indium. Moreover indium reserves are largely located in China and the U.S. Geological Survey predicts global supplies could be depleted within 10 years. Concentrated solar power which use mirrors to direct solar rays to heat water, also employs silver at rates of one gram per square meter. A global boom in such solar units would create silver shortages. Copper shortages are also a concern.”

      “Energy density: The amount of energy contained in a solar ray versus a lump of coal is reflected in their respective geographical footprint. A 1,000 megawatt coal-fired plant requires 1 to 4 square km to mine and transport the coal. In contrast it takes 20 to 50 square km or the area of a small city to generate the same amount of energy from a photovoltaic farm. A large solar industry will compete with other land uses.”

      Since 2004 Prieto has designed, consulted and helped to build more than 30 megawatts (MW) of solar photovoltaic (PV) plants. He even manages, operates and partially owns a PV plant that spills one megawatt of juice (enough to power up to 1,000 homes) onto the national electrical grid in the province of Extremadura.
      Given his vast technical experience Prieto also consults with governments around the world on solar renewable prospects.

      Some more bits from this article:
      “Spain, of course, gets more irradiation than any other European country. The nation’s sunny plains and deserts absorb about 1,500 terawatt hours of solar energy every year. That represents at least three times more power than what Spain’s 46 million citizens actually consume. (A terawatt hour by the way represents enough energy to operate one billion washing machines.)
      But achieving that goal might come with some staggering financial costs, significant land disturbance as well as disappointing energy returns. Prieto has even come to view solar power in its current big industrial mindset as just “another extension of fossil fuels.”
      And he’s not short of examples. The sun is renewable but photovoltaics are not. Just to make the silicon used to trap the sun’s rays on manufactured wafers requires the melting of silica rock at 3,000 Fahrenheit (1,649 Celsius). And the electricity of coal-fired plants or ultra-purified hydrogen obtained from fossil sources provide the heat to do that. It also takes a fantastic amount of oil to make concrete, glass and steel for solar modules.
      Unlike Germany’s solar revolution, which planted thousands of modules on rooftops, Spain focused its solar growth on installed ground facilities. They are, says Prieto, much more efficient and easy to maintain.

      What troubled Prieto most were the paltry energy returns of some 57,900 solar plants, both big and small. He reviewed Spain’s excellent data on the energy outputs of the nation’s solar network and then compared those findings to actual energy inputs. To his dismay Prieto found that solar offered only slightly better returns than biofuels. Or 2.4 to one.
      “That is not enough to maintain society as it is today.”

      His finding surprised many researchers and for good reason. Previous studies put solar returns as high as eight or even up to 30 to one in some cases, or almost on par with conventional oil.

      But most of this research used the same sort of best-case scenario modelling typically employed by car industry mileage studies. As long as the roads are flat, the fuel is good, the tires full and the driver competent, then great mileage can be achieved.

      But real life experience can be different for car mileage as well as the energy output for solar installations.

      Spain discovered, for example, that the earth is rarely flat (a big issue for tracking and directing solar rays in the right direction). Moreover the modules (only 15% efficient on average) rarely perform as expected.

      And what does Prieto think of big plans to industrialize the deserts of the U.S. southwest to provide power for the east? Or plans to colonize the Sahara desert of North Africa for European delights?
      Not much, he replies sadly. The engineer calculates that just one plan proposed by former French Prime Minister Nicolas Sarkozy was so big that it was obsolete before it harvested one solar ray. The plan would have covered 400 sq. km of land and burned three to six million tons of coal to erect 1.8 to 3.6 million tons of steel and two to four million tons of glass. Vast amounts of clean water and lakes of desalinated water would have been needed to maintain the plants. Yet the plan would have generated only 3% of the electricity that nations of the Mediterranean basin now consume. Such a scheme would exchange the political insecurity of oil and gas pipelines with high voltage cable lines.

      Big Solar would also turn poor countries like Morocco into virtual solar plantations or colonies that feed electrical power to wealthy at a project cost of $60-billion. (Another unrealistic forecast suggests that industrial solar plants in the Sahara could produce enough energy for 100 million homes for half a trillion dollars by 2050. Prieto says this plan, dubbed Desertec would be lucky to achieve 30 per cent of Europe’s electrical needs.)

    • Tom S says:


      The power generation figure (2,300 square miles) must be for Spain only. The figure of 2,300 square miles would mean about 60 GW of electricity (at 10 watts/m^2). That’s about 1300 watts per person in Spain, which is a reasonable estimate. The area of 2,300 square miles is just over 1% of the area of Spain and it’s a fairly densely populated country.

      The figure of 300 billion car batteries, however, seems way off to me. That’s more than 7,000 car batteries per person in Spain, just to store electricity. However, that figure might be a reasonable estimate for the entire world.

      -Tom S