Dozens of reasons why the world doesn’t run on algal biofuels

[ One of the few materials that could even scale up enough to replace oil are plants.  But algae won’t be one of them for the many reasons below.

Alice Friedemann  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”]


Algal biofuels aren’t sustainable, are too expensive, and need too much water, nitrogen, phosphorous, and carbon dioxide. Many Life Cycle Analyses (LCA) studies show a negative energy balance (more fossil fuel energy used than energy contained in the algal biofuel produced).

There are still tremendous technical difficulties that need to be overcome despite 60 years of research. The Department of energy stated that “a scalable, sustainable and commercially viable system has yet to emerge” and that “systems for large-scale production of biofuels from algae must be developed on scales that are orders of magnitude larger than all current worldwide algal culturing facilities combined” (DOE).

The National Academy of Sciences concluded in 2012 that the scale-up of algal biofuel production to replace 5% of U.S. transportation fuel (diesel, gasoline) would place unsustainable demands on energy, water, and nutrients.

Algae production does not sequester fossil carbon (DOE p 80). Several LCA studies of GHG emissions of algal biofuel production showed a higher level of GHG emissions than from gasoline (NAS 2012 Table 5-4). Carbon dioxide injected to promote algae growth tends to escape (Wald).  The CO2 generated by the power plant can only be effectively used by the algae while the sun is shining. The GHG emissions offset is 20% to 30% of the total power plant emissions due to CO2 off-gassing during non-sunlight hours and parasitic losses.

A 50-MWe natural-gas-fired power plant would require about 2,200 acres of algae cultivation area.  A 1,000-2,500 MWe coal power plant would need tens of thousands of acres of algae production and large volumes of water to provide a similar effective offset of 20% to 30% of the CO2 emitted (DOE p 80).

Algae production using the carbon from corn, soybeans, and other land plants competes with food and feed markets, and existing ethanol biofuel refineries for feedstock.

Photobioreactors need less water and land than open ponds, but are not feasible yet because even at a small scale, they use more fossil fuel energy than the energy contained in the algal biofuel.

Department of Energy goal: replace 5% of transportation oil with algae biofuel

Transportation uses 784 billion liters of oil in the United States, 5% of that is 10 billion gallons.  To produce that much algae, the two main ways are in open ponds or closed photobioreactors (i.e. plastic tubing).  The are many ways to produce biofuels within these systems. The water can be fresh or saline; the species seaweed, microalgae, or cyanobacteria; and the algae biomass can be harvested and processed in many ways, with different biofuel and coproducts outputs.

Where’s the Water?

The department of Energy states that the water to grow algae for biofuels could “approach the same order of magnitude as large scale agriculture” (DOE p 102). Water can easily become a “show-stopper” (DOE p 33).  Algae is a crop that uses more water than most land crops and gasoline:

  • Corn uses 133-142 liters of water per liter of ethanol produced (NAS 2012 Table 4-2).
  • A 50 million gallon per year facility could use 500 million to 50 billion gallons of water per year, depending on culture method used (Youngs)
  • Open pond systems can use up to 3,650 liters of water per liter of algal biofuel produced. Results ranged from 32 (100% of water recycled), 216, 438, 590, 656, 903 (p 105), 1613, 2140, to 3650 (NAS 2012 Table 4-1).
  • Gasoline only needs 2 liters of water per liter of gas, and oil sands 6.6 liters of water per liter of oil produced.  Algae biofuel needs orders of magnitude more water than petroleum or land crops.

Replacing just 5% of gasoline/diesel with algal biofuel would require somewhere between 123 billion (49,200 Olympic-sized swimming pools if 32 liters) to 143 trillion liters of water (3650 liters) — nearly as much water as is in Lake Tahoe, the 6th largest fresh water lake in America.

Waste, saline, and other low quality water

  • Wastewater would help prevent competition of algae with food and feed crops, as well as provide some of the nitrogen and phosphorous. But wastewater has significant reservoirs of algal pathogens and predators, heavy metals, and chemical compounds, it’s unlikely thousands of affordable flat acres of land for algae production exist near an urban wastewater treatment plant
  • It’s impractical, expensive, and energy-intensive to transport low quality water over long distances (DOE).
  • Is there enough wastewater? The 15,000 existing U.S. domestic wastewater treatment plants produce 47 trillion liters of wastewater effluent a day,  which may not be enough since up to 143 trillion liters of water could be needed.
  • Algae compete with thermoelectric-power plants for water as well. Of the 410,000 million gallons per day of total fresh and saline water withdrawals in the United States (2005), nearly half was for thermoelectric-power generation.
  • The stress on fresh water supplies is occurring across the entire country, and climate change is likely to mae this worse (DOE).
  • “Closed photobioreactors are not emphasized in this wastewater treatment discussion since they are likely to be economical only when also producing high-value products (>$100/kg biomass), which is unlikely when wastewater contaminants are present” (DOE p 84).


Even if a wastewater, saline, brackish, or other low-quality water source is found, water will evaporate and become so salty that it must be replaced with freshwater, and the salty water must be gotten rid of, which adds additional operational costs and is an environmental issue at inland locations.

  • A 2.5 acre open pond can lose 36,500,000 liters of water per year from evaporation losses (14.6 Olympic swimming pools) (NAS 2012 p 51), and additional losses can occur from stirring, sparging, and water flushing to lower salt concentration. The U.S. Department of Energy (DOE) estimates water loss of several hundred liters of water per liter of algal fuel produced in open ponds in arid, sunny regions of the United States.
  • Wigmosta estimated the water to compensate for evaporative water losses to be 312 trillion liters per year to produce 220 billion liters of algal biofuels — twice the amount of water (177 trillion liters in 2005) used for irrigated agriculture in the United States (USGS).
  • Water can not be 100% recycled. In addition to evaporative losses, loss during the drying of algae to prepare the biomass for processing into fuel is unavoidable, and some water also is lost during the extraction of oil from algae and in other processes of converting the algae to oil, ethanol, or some other energy product.
  • The evaporation estimates suggest that water loss on the order several hundreds of gallons of water per gallon of algal biofuel produced, could be a consequence of open system operation in the more arid and sunny regions of the country (DOE).
  • “With large cultivation systems, water demands will be enormous. For example, a hypothetical 1 hectare (ha), 20 cm deep open pond will require 530,000 gallons. In desert areas, evaporative losses can exceed 0.5 cm per day (so a 20 cm pond would entirely vanish in 40 days), which is a loss of 13,000 gallons per day from the 1 ha pond. The water used to initially fill the pond can be saline, brackish, produced water from oil wells, municipal wastewater, or other low quality water. But the water being lost to evaporation is fresh water, and continually making up the volume with low-quality water will concentrate salts, toxins, and other materials in the culture. This can be prevented by adding fresh water—a costly and often unsustainable option” (DOE).

Where’s the nitrogen?

Algae needs as much nitrogen (commercial fertilizer) as large scale commercial agriculture potentially, or even more (DOE p 103)

Between 6 to 15 million metric tons of nitrogen is required, 44-107% of our total use in the United States now.  Nitrogen required per gallon of algal oil: Algal biomass with 50% oil needs 1.3 pounds (.61 kg), algae of just 20% oil would need 3.3 pounds (1.5 kg) (Pate).  If the nitrogen is recycled then less can be used.

Commercial fertilizer costs are tied closely to the cost of energy supplies (natural gas and petroleum), and can be an appreciable factor in operational costs for algae just like large scale commercial agriculture. Without nitrogen fixation, algae can require as much, or even more nitrogen than conventional biomass crops. Large-scale commercial algae biofuels might need the same amount of nutrients as large scale agriculture does now (DOE p 103).

Where’s the phosphorus?

From 1-2 million metric tons of phosphorus would be needed, 20-51% of total phosphorus use now in the United States.  Phosphorus required per gallon of algal oil: Algal biomass of 50% oil needs 3 ounces (.083 kg), algae with 20% oil needs 7.4 ounces (.21 kg) (Pate).

Additional energy is required to remove phosphorous because it can  poison catalysts used in fuel conversion and damage vehicle catalytic converters.

Peak Phosphorus.  Both the National Academy of Sciences and Department of Energy algal biofuel research papers mention peak phosphorus, which is even more of a Malthusian limiting factor to human population than peak oil.

NAS Peak Phosphorous citations

  • “The long-term supply of phosphorus is also cause for concern, as many believe that the world’s supply of phosphate may have peaked or that a peak in supply is impending (Craswell).
  • “Given that readily available supplies of phosphorus may begin running out by the end of the 21st century, conservation and stewardship of U.S. phosphorus supplies are essential” (Vaccari, 2009).

Department of Energy Peak Phosphorous citation:  “Phosphorous appears to be an especially important issue as there have been calculations that the world’s supply of phosphate is in danger of running out” (Abelson).

Where’s the Carbon Dioxide?

Efficient algae production requires external sources of concentrated CO2 because not enough CO2 from the air penetrates the water (DOE, NAS 2012, Williams).

The Department of Energy stats that there there are almost 4,800 industrial sources of CO2, most of which are too far from locations where algae could be grown, and that will “constrain the extent to which algal biofuels production can be affordably scaled up” (DOE Exhibit 9.5).

Ideally, algal production would be located near an industrial CO2 source, that has nothing toxic to algae in the flue gas, to lessen the energy and cost of transporting CO2. But very few industrial CO2 sources also have thousands of flat acres of land nearby, and even if they do, additional  “extensive pipeline infrastructure” needs to be added to distribute the CO2 (DOE p 103).

Nearly two-thirds of the potential CO2 emitting sources are from electricity generation (coal and natural gas), but electric utilities are resistant to entering the biofuel business and are only keen for algae to be cultivated as a means of CO2 capture (the biofuel will release carbon dioxide so the utility won’t gain any CO2 credits, and still has to deal with the CO2 the algae aren’t consuming when it’s dark or not enough sunlight).

Many industrial CO2 sources have mercury, lead, arsenic, cadmium and other toxic elements, which algae are excellent at absorbing, so the co-product couldn’t be used for animal feed.

At a “large scale of algae production, parasitic losses from flue gas treatment, transport, and distribution could require more energy input than the output energy” of the “algae biofuels and co-products” (DOE p 80).

To produce 10 billion gallons of algal biofuel would require 6 to 9% of all CO2 emissions from all U.S. power plants.

The CO2 requirements for algal biofuel production are enormous. Pienkos estimated that 31-46 pounds (14-21 kg) of CO2 is needed per gallon of biodiesel, and Pate came up with similar results, about 31-77 (14-35 kg) per gallon of algal oil.

Long-term, since fossil fuels are going to be used up, algae would need to use lignocellulosic plant material to get carbon, and that takes a lot of energy and is tremendously ecologically destructive (see “Peak Soil“).

It’s too expensive

  • $1,000 per barrel, According to Jerry Brand,  Professor of Energy studies in the College of Natural Sciences, University of Texas.
  • The U.S. Navy has contracted to pay $12 million for 450,000 gallons: $27 per gallon in 2012 (Savage)
  • Solazyme in South San Francisco, sold the U. S. Navy algal fuel for over 8.5 million dollars of subsidy produced algae biofuel at $424 a gallon (that’s $17,808 per BARREL 424 * 42 gallons/barrel).
  • According to a 2010 research study by the Lawrence Berkeley National Laboratory, producing fuel from algae grown in ponds at scale would cost between $240 and $332 per barrel.
  • GreenFuel Technologies method is not be economically feasible due to fundamental thermodynamic constraints — even with flawless technological implementation the cost would be $800 per barrel.
  • Greenfuels went out of business in 2009 after spending more than $70 million due to the high cost of maintaining growth chambers and difficulty in controlling unpredictable algae growth.

The cost of algae food continues to be a problem.  The cheapest food is Brazilian sugar cane, and that is still too expensive.  If the food is going to come from sewage, then that limits the number of places algae can be grown to near sewage plants (most city sewage plants don’t have available land nearby).

Because of high costs, 18 years of algae hydrogen and biodiesel fuel research was terminated (after two decades) by the National Renewable Energy Laboratory as described in John Sheehan et al. 1998. “A Look Back at the U.S. Department of Energy’s Aquatic Species Program—Biodiesel from Algae”. Prepared for: U.S. Department of Energy’s Office of Fuels Development.  One of the reasons NREL stopped the algae biofuel program was that it was very obvious that the nutrients being added to grow the algae was costing far more than any oil that could ever be produced.

“The energy cost of extracting algae is 10 times the energy cost of extracting soybean oil,” according to Riggs Eckelberry, CEO of originoil.

Issues with open ponds

  • Algae need light to survive and grow. To get adequate light, the pond can only be six-inches deep, so ponds have to be large, which adds to construction and land costs.
  • The algae at the top hog all of the sunlight, so it must be stirred, which takes energy
  • Local conditions determine survivability, limiting the number or species that can be grown, often not the best possible algae with a high fat content to get more oil production, and often only seasonally if perfect conditions aren’t available year-round (i.e. freezes).
  • Contamination of open-pond algal cultures by other, undesirable algal species is unavoidable, unless the production strain can grow in specialized conditions that restrict the growth of those other species, i.e. high-alkalinity environments (NAS 2009).
  • Algae are a monoculture, making them more vulnerable to invasions by other algal species, bacteria, zooplankton, fungi, rotifers, ciliates, insects and insect larvae, protozoans, and viruses.  The invasion arrives by wind, rain, snow, insects, migratory waterfowl, and animals.
  • Destruction can happen fast: Algal cultures contaminated by Monas spp. or other species of protozoans often are totally decimated within 12 to 18 hours. The fungi chytrids have been detected in several algal cultures and often occur as epidemics, which sometimes result in the complete loss of cultures.
  • Invasions can reduce biomass yield and require costly interruptions of biomass production for system closure, cleaning, and strain re-establishment.
  • Potential for high ghg emissions: If carbon is supplied as CO2 gas in open ponds, then optimizing the size of gas bubbles is critical to ensure that the CO2 doesn’t escape and is taken up by algae.  A utilization rate of more than 10% of the supplied CO2 under working conditions in shallow ponds has been difficult — over 90% of the CO2 can escape. Other CO2 delivery methods have problems as well: pipes or tubes at the bottom releasing CO2 tend to get clogged by algae and other debris, needing regular cleaning

Why more fossil fuel energy is input than the energy contained in the algae biofuel (EROEI):

(a) Energy Return on Energy Invested (EROI) values from previously published LCA studies of algal biofuel production. (b) EROI values resulting from the “ worst ” (Low Productivity + Dry Extraction + anaerobic digestion) and “ best ” (High Productivity + Wet Extraction + anaerobic digestion) cases of this study. Center lines represent median values, edges of boxes represent 25th and 75th percentiles, and error bars represent 5th and 95th percentiles of the distributions resulting from 10 000 Monte Carlo simulations.

(a) Energy Return on Energy Invested (EROI) values from previously published LCA studies of algal biofuel production. (b) EROI values resulting from the “ worst ” (Low Productivity + Dry Extraction + anaerobic digestion) and “ best ” (High Productivity + Wet Extraction + anaerobic digestion) cases of this study. Center lines represent median values, edges of boxes represent 25th and 75th percentiles, and error bars represent 5th and 95th percentiles of the distributions resulting from 10 000 Monte Carlo simulations. Source:


Source: Sills, D.L., et al. Quantitative uncertainty analysis of life cycle assessment for algal biofuel production. Environmental science & technology.
  1. Energy to build the infrastructure of the algae biofuel facility – cement, plastic, and other materials; pumps, centrifuges, chemicals, filters, extensive CO2 pipeline infrastructure, waste treatment facilities, fuel processing, transport, storage infrastructure. Photobioreactors (closed systems) offer protection of the algae from the natural elements, but due to their pipes and tubes, they are more expensive to construct and require more energy to operate than open-pond systems.
  2. Current pond designs require extremely level surfaces, adding to the cost of construction (Youngs).
  3. Energy to treat waste or other low quality water and CO2 to decontaminate, disinfect, remove heavy metals (which algae are good at absorbing), and other remediation before it’s used to grow algae
  4. Energy to keep water within a narrow range of optimal temperature, no matter how hot or cold the outside temperature is
  5. Energy to cool photobioreactors or the algae will die from overheating, adding “prohibitively to the cost of operations” (DOE p 103).
  6. Energy to monitor and keep competing strains of algae, bacteria, and water plants out yet not kill the desired algae species.
  7. Energy to destroy or recover when algae predators, diseases, and infections kill the entire crop of algae. It can take months to recover
  8. Energy to prevent overcrowding
  9. Energy to keep pH levels constant
  10. Energy to keep saline levels constant
  11. Energy to keep water levels constant despite evaporation
  12. Energy to carefully control nutrient levels. Limitation of a key nutrient will have serious impacts on biomass productivity, too much of a nutrient may prove toxic.
  13. Energy to handle the water. Energy to pump the water, circulate the water so all the algae get sunshine, pump water between different areas of the system,
  14. Energy to recycle and treat waste water to re-use nitrogen and phosphorous, remove chemicals, toxic herbicides, antibiotics, endocrine disrupting compounds, heavy metals, and so on.
  15. Energy to remove waste oxygen
  16. Energy to feed the algae: make, transport, and deliver nutrients such as nitrogen, phosphorous, iron, and other trace elements
  17. Energy to transport and/or add pipelines to deliver carbon dioxide (it’s not “free” even if the pond is near a coal power plant)
  18. Energy to Harvest. Algae are a tiny fraction of the overall water, .4 grams/liter in open ponds and 3 grams/liter in photobioreactors.  Harvesting is highly energy- and capital-intensive and may require two or more methods: chemical flocculation, dissolved air flotation,  chemically induced coagulation, flocculation, sedimentation/settling, electroflocculation, and electrocoagulation techniques (DOE, NAS 2012)
  19. Energy to dewater the algae. This can take several very energy-intensive steps, such as  filtration ($10-$20/gallon), centrifugation ($20-$50 per gallon) and drying.  “As the desired percentage of dry biomass increases, energy costs climb steeply” (DOE).
  20. Energy to extract oil from algal cells for biofuel by sonication, microwave, rupture with solvents like hexane, chloroform, methanol, ethanol, butanol, ethyl acetate, and petroleum ether.
  21. Energy to convert the oil to a fuel via thermochemical/catalytic conversion, biochemical conversion, anaerobic digestion, energy to make the fuel comply with all regulatory requirements and customer requirements for utilization (e.g., engine performance and material compatibility)
  22. Energy to sterilize harvest filters and strainers, clean photobioreactor tubes and/or replace them
  23. Energy to make co-products from the algae remnants
  24. Energy to get rid of the waste products after algae is harvested that can’t be turned into co-products (i.e. because there are still heavy metals), spent synthetic plastic liner from open ponds or closed bioreactors, solvents used to rupture algal cells, phosphorous (which can poison catalysts used in fuel conversion and damage vehicle catalytic converters), inorganic salts, heavy metals, pathogens and chemical compounds from wastewater, and energy to move the wastewater somewhere else, etc.
  25. Energy to treat water that has to be released when it’s too saline for algae to grow in, and energy to replace this with fresh water. “Disposal of the spent water, which could contain salts, residual nitrogen and phosphorous fertilizer, accumulated toxics, heavy metals, flocculants, and residual live algal cells, could pose a serious problem, and treatment (e.g., desalination, activated charcoal filtration, etc.) of the recycled stream could be cost-prohibitive … sterilization to get rid of live cells that could harm local biodiversity would be very costly and energy-intensive” (DOE).
  26. Energy to recycle the water daily. Some algal cultures can double their biomass on a daily basis so half the culture volume must be processed daily. This is an enormous amount of water (260,000 gallons per day in a 1 hectare pond).  However, accumulated salts, chemical flocculants used in harvesting, or biological inhibitors produced by the strains themselves could impair growth if recycled to the culture. Moving around such large volumes of water is very energy-intensive (DOE).
  27. Energy to recycle the nutrients and carbon, “since wastewater flows in the United States are insufficient to support large-scale algae production on the basis of a single use of nutrients. Even with recycling, importation of wastes and/or wastewater will still be needed…to make up for nutrient losses” (DOE).
  28. Energy to deliver the fuel.  “Although the biofuel product(s) from algal biomass would ideally be energy-dense and completely compatible with the existing liquid transportation fuel infrastructure (delivered cheaply via pipelines rather than energy-intensive trucks, trains, barges), few studies exist that address outstanding issues of storing, transporting, pipelining, blending, combusting, and dispensing algal biomass, fuels intermediates, biofuels, and bioproducts” (DOE).  An algal biofuel made to replace gasoline or diesel, must be made to the exact specifications of energy density, oxidative and biological stability, lubricity, cold-weather performance, elastomer compatibility, corrosivity, emissions (regulated and unregulated), viscosity, distillation curve, ignition quality, flash point, low-temperature heat release, metal content, odor/taste thresholds, water tolerance, specific heat, latent heat, toxicity, environmental fate, and sulfur and phosphorus content. Failure of a fuel to comply with even one of these can lead to severe problems.
  29. Energy to keep algae biofuel from going rancid and to extend its shelf life.
  30. Energy to deliver the algal biofuel. Unless it can directly replace diesel fuel, it can’t be delivered cheaply by pipeline, but more energy-intensively, like ethanol, via truck, train, or barge

Peer-reviewed science has shown that the Energy Returned on Investment (EROEI) is negative or too low

“If the EROEI is less than 1.0, energy needed to make a fuel is greater than energy contained in the fuel and co-products, so algal biofuels that have an EROEI of less than 1 are clearly unsustainable. Microalgal fuels use high-value energy inputs in the form of electricity and natural gas. If these high-quality energy sources are downgraded in the production of algal fuels, it is certainly a sustainability concern. Hall (2011) proposed that EROI greater than 3 is needed for any fuel to be considered a sustainable source.” (NAS 2012 pp 126, 200-201).  In 2012 Hall and Lambert make the case that an EROEI of at least 12 is necessary to maintain civilization as we know it (Lambert).

Estimated values for energy return on investment of Open Pond algal biofuels range from 0.13 (or 7.76 times as much fossil fuel input to energy contained in the algal biofuel) to 3.33.  Closed bioreactors use up to 57 times more fossil fuel energy than what’s contained in the algal biodiesel (EROI = .017), and at best 1.4 times as much energy (EROI=.71), so they’re clearly out of the running, which is why this article focuses more on open ponds (NAS 2012 tables 4-6 and 4-7). Tubular and annular reactors are thought to require far more energy to operate than is contained in the biodiesel product (NAS 2012 p 128).

Depending on how the open-pond algae was harvested, extracted, processed, and the credit given to co(products), researchers found these ranges of EROEI: Brentner  .13, .28, .96, Clarens 1.06, 1.36, 1.99, 2.32, Greet baseline pathway .39, Sander 1.77, 3.33, Stephenson 1.60, Vasudevan .3, 2.51

The National Academy of Sciences (NAS 2012) concludes: “An energy return on investment (EROI) of less than 1 is definitely unsustainable. An algal biofuel production system would have to have or at least show progress toward EROI within the range of EROI required for sustainable production of any fuel (Pimentel and Patzek, 2005). Algal biofuels would have to return more energy in use than was required in their production to be a sustainable source of transportation. Microalgal fuels use high-value energy inputs in the form of electricity and natural gas. If these high-quality energy sources are downgraded in the production of algal fuels, it is certainly a sustainability concern that can only be truly understood through careful life-cycle analysis. EROI of 1, the breakeven point, is insufficient to be considered sustainable. However, the exact threshold for sustainability is not well defined. Hall (2011) proposed that EROI greater than 3 is needed for any fuels to be considered a sustainable source. EROI can be estimated with an LCA that tracks energy and material flow”.

The U.S. Department of Energy states that “optimizing extraction systems that consume less energy than contained in the algal products is a challenge due to the high energy needs associated with both handling and drying algal biomass as well as separating out desirable products” (DOE).

The Department of Energy points out that just the energy to dry out / concentrate the algae could take more energy than the energy content of the algae:  The energy content of most algae cells is about 5 watt-hours/gram given the energy content of lipids, carbohydrates, and proteins. The energy requirements can be calculated in watthours/gram of algae for harvesting, de-watering, and drying as a function of the volume percentage of algae in harvested biomass. Based on the latent heat of vaporization of water at 0.54 watt-hours/gram, energy balance can become an issue in systems that propose to take algal biomass and concentrate / dry it to enable downstream processing and extraction because of the high volumes of water that must be evaporated away (DOE p 40).

The studies that gave algae biofuel a positive EROEI depended on co-products to tip the balance from a negative energy reutrn.  But the Department of Energy notes that “if biofuel production is considered to be the primary goal, the generation of other co-products must be correspondingly low since their generation will inevitably compete for carbon, reductant, and energy from photosynthesis…and coal-fired power plant carbon dioxide” will have toxic elements and make it unsuitable as an animal feed.

Where’s the land?

The land needed to grow enough algae to replace 5% of petroleum transportation fuel, 10 billion gallons, is 1.5 million acres (southwest), 2.2 to 2.4 million acres (Georgia/Florida and Midwest), 4.8 million acres (Texas) (NAS 2012 Fig 4-3). That’s a lot of flat land!

If 5.5% of the land in the lower 48 states were used to grow algal biofuel, we would only replace 28% of total U.S. petroleum used for transportation (Wigmosta).

algae sunshine temp us map


Exhibit 9-4. a) Regions with annual average climate over 2800 hours annual sunshine, annual average temperature over 55 F, and over 200 freeze-free days (DOE)

algae sites near co2 and wastewater


Exhibit 9-4. b) Fossil-fired power plant sources of CO2 within 20 miles of municipal wastewater facilities in the preferred climate region (DOE).


The ideal commercial site would be:

  1. Thousands of acres of cheap, flat land in the same place (to get economies of scale), with less than a 5% slope for both open ponds and photobioreactors, and half as much land again for other essential facilities such as inoculum cultivation; systems to deliver inoculum to cultivation vessels; harvesting systems; reservoirs for holding water; waste management, storage, recycling facilities; and other support systems.
  2. In a sunny, warm, freeze-free, low elevation region with a long growing season (Exhibit 9-4 a, parts of California, Arizona, New Mexico, Texas, Louisiana, Georgia, or Florida).  Sunlight is the dominant and rate-limiting factor for algal productivity.
  3. With over 40 inches of annual rainfall (Hawaii, Northwest, Southeast),
  4. Low evaporation rates.  The highest evaporation rates of over 60 inches per year are in California, Arizona, and New Mexico
  5. Be near an industrial CO2 source (Exhibit 9-4 b)
  6. Near a wastewater treatment plant (exhibit 9-4 b) or plentiful cheap saline or other low quality water, without harmful chemicals, at a shallow depth to limit the energy required to pump it
  7. In a city to lessen the cost of delivery of the biofuel and to be near a wastewater treatment plant
  8. On land that is affordable, has no recreational use, would not compete with agriculture, and has little wind to keep dust and sand out of open ponds
  9. Is not subject to severe weather (heavy rain, flooding, hail storms, tornadoes, hurricanes)
  10. On land that doesn’t compete with a solar facility, which also needs flat land and water for cooling, mirror, and panel washing.
  11. On land that’s not too close to the marine environment which can be highly corrosive to materials and requires higher quality and more expensive materials and maintenance.
  12. Land near cheap saline, brackish, and other low quality water to not compete with agriculture
  13. Soil that’s not permeable or porous to reduce the energy required to line and seal the ponds

Is there even 1 site in the United States with all of these features? Is an ideal site even possible?  There are too many conflicts, i.e. #3 the Northwest gets enough rain but not enough sun, #2 the warm and sunny frost-free regions have too high an evaporation rate which makes the #12 low quality water so salty it must be replaced with scarce fresh water, #9, the central, Southwest, southeast, and coastal areas all get severe weather, #5 Coal power plants produce 40% of total CO2 (2 billion metric tons) but ideal sunny and warm California has no coal power plants

Does it scale up? 

There are no commercial facilities because what works in a small prototype simply hasn’t worked when scaled up, because:

  1. Algae that do well in the laboratory usually don’t survive in the field. Bio-engineered super-algae may be even more vulnerable to disease and predators than the hardy, tested-by-nature natural strains used now.
  2. Algae that are high-fat reproduce slowly.
  3. Enclosed facilities use polycarbonate, which lasts only 10-15 years
  4. How can you justify the expense of enclosed facilities, the time and expense of keeping the innards clean and preventing algae sticking to them?
  5. Bioreactors that are efficient in the lab can’t be scaled up to an industrial level
  6. Algae produce oil to protect themselves from long periods of darkness (night) and lack of food. But when in this stress mode, they grow very slowly.  To try to make them grow faster goes against their very nature!
  7. Not one algae producer has been profitable or produced useful quantities of oil as of October 2011.
  8. The only companies that make money on algae today are the ones who harvest omega-3 fatty acids for nutritional supplements at a price much higher than the cost of crude oil, or for use in cosmetics.
  9. Nothing but failure so far after decades of trying
  10. Japan also spent hundreds of millions of dollars trying to make algae into fuel, and didn’t succeed.
  11. Nutrient sources and water treatment/recycling are technically trivial and inexpensive at small scales and yet represent major technical and economic problems at commercial scales.
  12. Small scale lab experiments with algal oil production of 50-60% oil doesn’t happen at larger scales and it isn’t understood why because we know so little about lipid biosynthesis and regulation
  13. There’s no well-defined and demonstrated industrial-scale method of extracting and separating of oils and lipids from algae to produce biofuels. Existing techniques are only suitable for analytical- and laboratory-scale procedures, which use freeze dried, pulverized biomass. That will be impossible at a commercial scale, because microalgae and cyanobacteria are single cells suspended in water at concentrations below 1% solids (land plants are often over 40% solids). The energy to concentrate and dry the algae on a large scale would be far greater than the energy contained in the algae (DOE)

Environmental and ecosystem issues

Putting large areas of water in arid or semi-arid environments could alter the local climate by increasing humidity and reducing temperature extremes.

If water is not treated, the risks to the natural environment include eutrophication of water, contamination of groundwater, and salinization of fresh water sources, which will also happen if there’s a flood, earthquake, tornado, hurricane, if the pond breaks or leaks, from high rainfall or winds, or if spills occur during transfers of fluid during process stages or waste removal.

Releases of some exotic algal species, particularly from open-pond cultures, could threaten the integrity of local and regional ecosystems (Ryan, 2009). Blooms of exotic species could displace native species, with adverse impacts on organisms that feed on those species propagating through aquatic food webs. An example is the diatom Didymosphenia geminata (also known as Didymo or Rock Snot) that can cause dense algal blooms. The blooms block sunlight and cause a local decline in native plant and animal life.

LCA studies of GHG emissions for algae biofuel production vary from a net negative value (that is, a carbon sink in 2 of the 5 studies) to positive values substantially higher than petroleum gasoline in 3 of the 5 studies (Table 5-4). None of the studies addressed the potential issue of indirect land-use change from biofuels.

Poor Photosynthesis

Algae are inefficient photosynthetic reactors — they don’t consume CO2 when the sun isn’t shining, and allocate only a tiny fraction of captured solar energy into lipid production.

The majority of light that falls on algae isn’t used.  At high density, the algae closest to the light absorbs all of it, so the light doesn’t reach more distant cells. Even when exposed to high light, algal photosystems have built-in strategies to prevent the over-absorption of light energy, which can lead to oxidative damage. And a large majority of absorbed incident light is dissipated as heat and could be considered “wasted.”   Under high light stress, excess electrons … can inhibit photosynthesis and damage membrane lipids, proteins, and other macromolecules. (DOE).

How are you going to get rid of all the waste after you’ve extracted the oil?

There are many ways to produce biofuels.  If an open pond is used to produce green diesel to provide 5% of America’s transportation fuel (39 billion liters), after the oil is removed (30% of the algae), you’d have the other 70%, 300 million tons, to dispose of. Some could be anaerobically digested to return nutrients and produce power, or used for coproducts like animal feed if all pollutants and toxins are removed, but there’d still be a lot of sludge to get of. No matter what is done with the 300 million tons, the energy used to deal with it will lower the EROEI. The National academy of Sciences concludes “Although coproduction of fuel and other products can improve the economics of algal biofuels, it has limited potential and cannot be the single remedy to improving the economic viability of widespread and large-scale deployment of algal biofuels. Only animal feedstuff has a large enough market to absorb commercial scale sludge, there’s not enough demand for other possible byproducts like nutraceuticals. (NAS 2012 P 85, 96)

Too many technical hurdles

8 Mar 2013. Exxon at least 25 years away from making Algae (Bloomberg).   “Exxon Mobil Corp. (XOM)’s $600 million foray into creating motor fuels from algae may not succeed for at least another 25 years because of technical hurdles, said Chairman and Chief Executive Officer Rex Tillerson.  “What we’ve come to understand is the hurdle is pretty high and the hurdle seems to exist at the basic science level, which means it’s even more difficult to solve. These are very challenging problems.”  So far, scientists haven’t been able to develop a strain of algae that reproduces quickly enough and behaves in a manner that would produce enough raw material to supply a refinery, Tillerson said March 7 on PBS television’s “Charlie Rose” show.

10 Oct 2007. Chris Somerville, Director, Energy Biosciences Institute, U.C. Berkeley “Technical issues associated with the development of lignocellulosic biofuels Colloquium”.  I was present at this talk, and he practically gave my “Peak Soil” paper — he thought it would be at least 20 years of basic science research before any kind of useful fuel could be scaled up for the market.  I think he was honest at this talk because only about 30 Energy Resources Group PhD and postdoc students attended this seminar.

National Academy of Sciences 2012 hurdles

Serious barriers remain for reproducing optimal growth and productivity conditions at a commercial scale:

  1. Maintaining the stability of the culture and delivering the required nutrients and other resources in an efficient manner at commercial scales
  2. Among the biggest challenges for strain selection is the difficulty of translating desirable strain properties from the laboratory to the field. A desirable strain would have robust growth in open ponds under natural weather and cultivation conditions, and would retain attributes that are selected and measured in the controlled conditions of the laboratory. However, the ability to grow well and compete when exposed to environmental conditions is difficult to predict. Few strains are robust in outdoor mass cultivation, and years of investment in time and process went into their commercial development.
  3. Although high amounts of oil production are necessary, this is hard to do because most eukaryotic algae accumulate increased amounts of oil only in response to nutrient stress or in late exponential growth phase and do so at the expense of a reduced growth rate.
  4. The more biomass that’s concentrated, the less light penetration, which limits the growth rate of cells below the surface.  But solving the problem by stirring the water up reduces the energy returned on energy invested.
  5. Other factors besides light may possibly limit algae reproduction, such as quorum sensing, interspecies allelopathic interactions, and other mechanisms that limit population density.
  6. A long-time goal is to improve photosynthetic efficiency by reducing losses from photorespiration, enhancing photosystem stability and efficiency, etc. However, 30 years of efforts in this area have not yielded any progress in higher plants or algae.
  7. Tubular photobioreactors have many problems: Algae wall adhesion, biofouling, large pressure drop, and gradients in pH, dissolved oxygen, or CO2 can occur along the tube length.
  8. LiveFuels, Inc. in testimony before the committee stated that the economics of producing algal biofuels at a cost that is competitive with fossil fuels is impossible (NAS 2012 p84)
  9. Most of the reports on algal biofuels assume that FAME is produced. FAME is not a hydrocarbon fuel, but an ester that can’t be used in cold climates, has a high viscosity that makes it difficult to pump, has cloud point issues when wax crystals form that can lead to gel formation and harm engines, and biodegrades with long-term storage.
  10. Nutrients cannot be recycled 100 percent because of losses as a result of precipitation1 and nutrients tied up in dead algal biomass. The dead algal biomass cannot be left in the pond to mineralize because of undesirable consequences to the culture medium. The formation of such suspended sludge and the accompanying dissolved organic matter is a sink for nutrients and reduces light availability for the growth of live algae. These practical problems of nutrient recycling have not been discussed in the literature.

Department of Energy hurdles

It would be great if the algae could secrete the biofuel to avoid having to harvest algae. but this isn’t easy:

  • if the fuel is volatile it could explode or catch on fire, so it could only be made in bioreactors
  • secretion may not make the fuel easy to get out, for example, if it’s in a lipid biofilm matrix
  • An abundance of lipids could unfavorably alter fluidics properties or provide a carbon source favoring growth of contaminants.
  • secretion of other products into the growth medium could make these compounds vulnerable to contaminating microbes

Ideally the algal biofuel would be made exactly the same as gasoline or diesel so it could travel in pipelines and be directly used in trucks and autos.  All plant-derived biodiesel fuels have the problems of lower oxidative stability than petroleum diesel, higher emissions of nitrogen oxides (NOx), and cold-weather performance problems Algae-derived biodiesel has additional difficulties including: 1) contamination of the esters with chlorophyll, metals, toxins, or catalyst poisons (e.g., sulfur and phosphorus) from the algal biomass and/or growth medium; 2) undesired performance effects due to different chemical compositions; and 3) end-product variability.

One of the main reason there aren’t any commercial cellulosic ethanol refineries yet is that it is so hard to break down plants, which evolved over hundreds of millions of years to avoid being eaten.  Many species of algae also have cell walls with complex composition and structure that are hard to break down into simpler sugars to make conversion into biofuels possible.

Photobioreactor issues:

  • Haven’t been able to scale them up
  • Don’t lose as much water to evaporation as open ponds, but must be kept cool, so closed systems that spray water on the surfaces or employ cooling towers to keep cultures cool will lose some if not possibly all of the water savings of such systems
  • Like open ponds, are also vulnerable to algae and algal predators that invade and take over the algae grown in the bioreactor
  • It’s hard to get the right mix of CO2 and O2
  • Temperature must be very carefully maintained
  • They are unlikely to be sterilizable and may require periodic cleaning due to biofilm formation

Heterotrophic cultivation is expensive and is likely to compete with other biofuel technologies for feedstock

Potential harmful effects

More studies need to be done on:

  1. the potential harm to wildlife
  2. Waste products from processing algae to fuel
  3. Possible presence of pathogens if wastewater is used for cultivation
  4. effects on nearby natural ecosystems
  5. adverse effects of genetically engineered algae
  6. adverse effects of algae on natural environments and potential alteration of species composition in receiving waters
  7. potential emissions of unknown, unexpected, or unidentified toxins
  8. safety and nutritional quality of feedstuff coproducts
  9. potential land conversion and its effects on GHG emissions
  10. land-use changes if pasture and rangeland are converted to algae cultivation
  11. effects of net evaporative losses, especially in arid regions where increased humidity could alter local climate and temperature extremes
  12. GHG emissions over the life cycle of algal biofuels. Algae production is higher the more CO2 used, open ponds can lose introduced CO2
  13. Potential mosquitoes and diseases borne by mosquitoes
  14. competition between agriculture and algae production for water (especially depleting aquifers), nitrogen, and phosphorous
  15. Mosquitoes and mosquito borne diseases (encephalitis, West Nile, Dengue fever, etc). Even though water is stirred and agitated, the relatively still edges of open ponds, puddles, and storage vessels are good for mosquito larvae, which thrive on algae and potentially lower production.

Production is seasonal

Cultivation in ponds is possible in the flat regions of southern and central California, but temperature fluctuations will limit production to 7 months of the year (Belay).


According the the Department of Energy: “As global petroleum supplies diminish, the United States is becoming increasingly dependent upon foreign sources of crude oil. The United States currently imports approximately two-thirds of its petroleum, 60% of which is used for producing transportation fuels. The rising energy demand in many rapidly developing countries around the world is beginning to create intense competition for the world’s dwindling petroleum reserves (which is a muted bureaucratic way of shouting War!).

There are too many showstoppers:

  1. Gargantuan amounts of water, phosphorous, nitrogen, carbon dioxide to replace just 5% of oil
  2. To replace just 5% of our oil would require 2,700 to 3,600 square miles of flat land with very optimistic assumptions (algae 50% oil, lots of sun, DOE p 102). Flat land is usually spoken for. Desert flat land is short on water, CO2, far from cities so high transport costs, etc.
  3. Negative energy returned on energy invested — there are far too many steps, each requiring fossil fuels throughout their life cycles, and each step lowers the potential EROEI.  Much of our Petroleum probably comes from algae, but it comes for free, brewed by the sun over millions of years, just pump it out. To repeat the experiment requires enormous amounts of nutrients, infrastructure, chemicals, pumps, stirrers, filters, wastewater treatment, fighting off predators and so on.  The energy to get rid of the water alone is a showstopper — it’s one of the main reasons corn ethanol has a negative EROEI, and there’s far more water to get rid of with algae.
  4. We’re out of time. Algal biofuels have been studied for 60 years and scientists are no closer to commercial level production than 60 years ago. Conventional oil peaked in 2005, and we can’t keep production flat much longer with lower quality petroleum resources.  Algal biofuels have hundreds of “barriers” to overcome, barriers that I think I’ve shown can’t be overcome.


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