Preface. In the comments section, Ray Universe pointed out an excellent article, The bright future of solar thermal powered factories, about solar collectors and what they can do. Some important points:
A large share of energy consumed worldwide is by heat. Cooking, space heating and water heating dominate domestic energy consumption. In the UK, these activities account for 85% of domestic energy use, in Europe for 89% and in the USA for 61%. Heat also dominates industrial energy consumption. In the UK, 76% of industrial energy consumption is heat. In Europe, this is 67%. Few things can be manufactured without heat.
Although it is perfectly possible to convert electricity into heat, as in electric heaters or electric cookers, it is very inefficient to do so. It is often assumed that our energy problems are solved when renewables reach ‘grid parity’ – the point at which they can generate electricity for the same price as fossil fuels. But to truly compete with fossil fuels, renewables must also reach ‘thermal parity‘.
It still remains significantly cheaper to produce heat with oil, gas or coal than with a wind turbine or a solar panel.
In today’s solar thermal plants, solar energy is converted into steam (via a steam boiler), which is then converted into electricity (via a steam turbine that drives an electric generator). This process is just as inefficient as converting electricity into heat: two-thirds of energy gets lost when converted from steam to electricity. If we were to use solar thermal plants to generate heat instead of converting this heat into electricity, the technology could deliver energy 3 times cheaper than it does today.
43% of industrial heat demand in Europe is above 400 °C (752 °F). These include many of the industrial processes that we need to manufacture renewable energy sources (wind turbines, solar panels, flat plate collectors and solar concentrators) as well as other green technologies (like LEDs, batteries and bicycles). Examples include the production of glass (requiring temperatures up to 1,575 °C/2870 F) and cement (1,450 °C / 2640 F), the recycling of aluminum (660 °C / 1220 F) and steel (1,520 °C / 2770 F), the production of steel (1,800 °C / 3275 F) and aluminum (2,000 °C / 3600 F) from mined ores, the firing of ceramics (1,000 to 1,400 °C / 1830 to 2550 F) and the manufacturing of silicon microchips and solar cells (1,900°C / 3450 F ).
The author points out that solar furnaces can produce temperatures up to 3,500 °C (6,332 °F), enough to manufacture microchips, solar cells, carbon nanotubes, hydrogen and all metals (including tungsten which has a melting point of 3,400 °C). These temperatures can be achieved in just a few seconds, but then uses as an example a Odeillo in France, built in 1970, that can only generate 1 MW. If this is such a good idea, why aren’t there more of them? How can civilization be maintained on 1 MW, when the average natural gas power plant generates 500 MW? Smaller furnaces can be built, but they only produce 15 to 60 kW.
Earlier in the article the author points out that solar panels and wind turbines do not need fossil fuels to operate, but they do need fossil fuels for their production. You won’t find any factory manufacturing PV solar panels or wind turbines using energy from their own PV solar panels or wind turbines. Yet he ignores that this is an issue for solar collectors. He also ignores the transportation component of the dependency on fossils and other fossil dependencies, which I describe on my post 46 Reasons why wind power can not replace fossil fuels:
Consider the life cycle of a wind turbine – giant diesel powered mining trucks and machines dig deep into the earth for iron ore, fossil-fueled ships take the ore to a facility that will use fossil fuels to crush it and permeate it with toxic petro-chemicals to extract the metal from the ore. Then the metal will be taken in a diesel truck or locomotive to a smelter which runs exclusively on fossil fuels 24 x 7 x 365 for up to 22 years (any stoppage causes the lining to shatter so intermittent electricity won’t do). There are over 8,000 parts to a wind turbine which are delivered over global supply chains via petroleum-fueled ships, rail, air, and trucks to the assembly factory. Finally diesel cement trucks arrive at the wind turbine site to pour many tons of concrete and other diesel trucks carry segments of the wind turbine to the site and workers who drove gas or diesel vehicles to the site assemble it.
And also, how can factories be relocated to these facilities and scale up? Does all manufacturing need to be moved to within 20 degrees of the equator for maximal sunshine? Even then the peak sunshine is only a few hours a day, and Utility scale energy storage has a long way to go to make renewables possible.
But this article does a good job of explaining why electricity isn’t enough to make an energy transition with.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
Kurup, P., et al. 2015. Initial Investigation into the Potential of CSP Industrial Process Heat for the Southwest United States. National Renewable Energy Laboratory.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
Industries use enormous amounts of fossil fuels to generate heat and electricity to make products like steel, cement, chemicals, glass, and refine petroleum, with nearly three-quarters of energy used in the form of heat. Industry uses 30% of all energy, and 83% of that energy is generated by fossil fuels mainly to create process heat directly, indirectly with steam heat, or to generate electricity at the factory for reliability and to operate machine drive equipment (EI 2010).
It is possible for a Parabolic Trough collector (PTC), which looks like a giant upended cattle trough, to make some of this industrial heat and replace some of the fossil fuels used (mainly natural gas).
But the industrial uses this concentrated solar power collection is most useful for are heat applications from 110 to 220 C (230 – 430 F), especially those processes that use pressurized water or steam.
So that leaves quite a few very important industries out, since they use 2000 F heat or more, such as iron, steel, fabricated metals, transportation equipment (cars, trucks), computers, electronics, aluminum, cement, glass, machinery, and foundries.
Industries where solar industrial process heat (SIPH) might be used are paper, dairy, food, beer, chemicals, and washing/cleaning. No doubt some processes within other industries like plastics and rubber, textiles, and others also have a need for industrial process heat that’s less than 430 F.
NREL isn’t proposing gigantic, billion dollar concentrated solar power collectors like the ones that take up miles of land in the deserts of California, Nevada, and Arizona.
Rather they suggest that much smaller facilities could be built. Have been built actually, Frito Lay set aside 5 acres to use heat to fry potato chips in Modesto, California. Prestage Foods in North Carolina also has 7 acres of PTC to heat 100,000 gallons of water a day for their turkey processing operations. Currently there are 16 other SIPH plants (9 food & dairy, 4 breweries, 2 desalination & water treatment, 1 subway washing).
Another reason these plants need to be small and local is that unlike electricity, it’s too hard to transfer hot fluids like steam more than a few hundred meters, while electricity can be sent for hundreds of miles. So solar collectors need to be next to the manufacturing plant.
But SIPH can barely make a dent in the industrial process heat required. In 2013 a German study found that solar heat generation could only replace 3.4% of overall industrial heat demands. This 3.4% would require 16 Terawatt hours (TWh) a year, which would require 46 Nevada Solar One plants. This plant cost $266 million, so that’s $12.2 billion for this small fraction of manufacturing.
Like all electricity generating contraptions, PTC and other concentrated solar power collectors can’t outlast the age of oil, since their life cycle depends on fossil fuels from beginning to end — from mining, ore crushing, metal smelting and fabrication, transportation by diesel trucks, ships, and trains, and finally delivery with een more diesel. If solar collectors were good at generating the 3000 F temperatures needed by iron, steel, and aluminum, or the 2700 F needed by cement these contraptions, then they’d come closer than wind or solar PV towards replacing fossils and being able to make themselves from their own energy, but that simply isn’t the case.
Just look at the materials needed for a 1 Gigawatt Parabolic trough collector:
Material Tons > PTC can generate
Iron 650,000 Yes
Cement 250,000 Yes
Steel 240,000 Yes
Sodium Nitrate 220,000
Glass 130,000 Yes
Silicon sand 92,000
Table 1. Materials needed per GW for a parabolic trough collector (Pihl 2012)
In addition thousands of tons of Copper (3200), Chromium (2200), Foam glass (2500), Magnesium (3000), Manganese (2000), Rock Wool (4700), Soda Ash (18,000), and hundreds of tons of Aluminum (740), Fibreglass (310), Molybdenum (200), Polypropylene (500), Zinc (650) and many more materials as well.
The years of reserve life for many aren’t far off Iron (33), Copper (39), Manganese (48), Chromium (16), Nickel (49), Molybdenum (43), Niobium (48), and Silver (25), so solar collector contraptions, if not limited by oil, natural gas, and coal for their construction will be limited by their materials.
EI. 2010. Manufacturing Energy and Carbon Footprint Sector: All Manufacturing (NAICS 31-33). Energetics Incorporated for the U. S. Department of Energy
Pihl, E., et al. 2012. Material constraings for concentrating solar thermal power.
- Concentrated Solar Power: Water Constraints
- Concentrated Solar Power: location, location, location
- Why Concentrated Solar Power is not a good choice for a 100% Renewable Energy System
- Taxpayers are paying for a concentrated solar project — Ivanpah– that doesn’t work
- CSP with thermal energy storage is seasonal, so it can not balance variable power or contribute much power for half the year