The Myth of Renewable Energy

A great deal more austerity. However, it makes a rather weak argument about a very real trade off problem, that problem is the water-energy trade off problem. In almost all forms of energy generation, it is not usable energy that is created directly, instead, heat is generated, the heat is used to do work, and the work is used to store the energy. So, the classic steam turbine has water heated to gas, and the resulting steam spins the turbine, and that carries wires through a magnetic field, which generates a corresponding electrical current, and that current is sent down wires. Another water energy trade off is to have wind turbines pump water up a shaft, which then is allowed to fall, spinning turbines, when power is needed. Bio-fuels, the same way: water is used to grow plants, the plants fix sunlight into hydrocarbons.

The solution to the water energy problem is more energy, because energy can be used to get water. This, however, lowers the Life Cycle Output of the energy system. LCO or LCA is the expected usable energy out, divided by the expected usable energy used to create and run a system. So if a system produces 10 watts for every watt it takes to build, run, and dispose of it, then its LCA is 10. The 20th century got by on a miracle: namely petroleum has a high LCA, and its its own storage mechanism. Gasoline has great power to weight storage capacities with internal combustion. And internal combustion engines can be built of very cheap metals. There are many quandaries in replacing hydro-carbon energy, and the water energy trade off that the piece mentions is one of them, but it is one of scale. Once there is a large enough renewable base, then the low LCA that getting the water to run it has, is not a problem. It is at the beginning, when the return is eaten through by the water problem, because there are competing uses for water that have much higher economic returns in the short run, such as airconditioning and agriculture. None of these uses want to pay much higher rates for water so that people not yet born can have the advantages.

Where the article falls down is pressing an agenda, and making sloppy equivalences. The first is equating capital requirements with expendable requirements: we don't burn the rare earths we use in kinetic energy extraction ? that is water, wind, and geothermal ? and in fact, rare earths, are not, as a percentage of the earth's crust, all that rare. For example, wikipedia has this chart [wikipedia.org]. It shows that all of the Lanthanide rare earths, plus scandium and yttrium, are more common than either gold or silver, many are more common than tin, and some more common than lead. The problem with them is that they tend to be found near the Actinide rare earths, particularly Thorium. If you have seen a press for "Thorium reactors" it is because exploitation of rare earths leads to Thorium by product, and reactors which burn it would be fantastically profitable, for the people who sell the rare earths. In reality, they have the same problems, only more so, of actively cooled salt reactors. Namely, they work until they blow up. The Chinese dump their Thorium in a holding lack, which, should it break, would contaminate large areas of land and volumes of water.

Side note: how is it that a browser's spell check doesn't know Actinide?

But for all of that, rare earths are not burned, the way for example Lithuium is not burned in a battery and can be recycled. These are recyclable, which is different from consumable. Hence moving from consumption of hydrocarbons, which really are burned, to using rare earths in capital energy, is a positive step, and while the author of the paper implies that there would be rare earth shortages, the reality is that this is not the case, and substitutes in the form of ceramics and active magnets (See Rare Earth Prices Plunge as Manufacturers turn to substitutes [mining.com]

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/bqyGP34ukOc/the-myth-of-renewable-energy

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