The "Renewables Gap"November 29, 2009
The estimated EROEI ("energy return on energy invested") for wind turbines varies widely, all the way from 4:1 (pessimistic) to 24:1 (optimistic) — comparable to other forms of energy generation with fossil fuels. But unlike generating electricity from coal or natural gas, for wind almost all of the energy investment is up front, namely, in the manufacture and set-up of the wind turbine. This up-front investment will have to be huge and will take a big chunk out of the rest of the economy. This chunk is the "renewables gap." How big a chunk? Vail looks at the requirements for offsetting just 5% of the energy we get from oil, and then makes some generous assumptions, including an optimistic 20:1 estimate of the EROEI of wind power. He comes up with the energy equivalent of about 7.5% of our total oil supply for a year to build these wind turbines. Under a pessimistic scenario ( 4:1 EROEI), it could be over half of our oil supply! And to achieve further reductions, we’d have to do the same thing next year. The current political climate makes this sort of thing impossible. The oil price spikes of 1979 and 2008 led to a decline in oil use of about 5%, with extensive economic damage. No political leader has the courage to suggest diverting 50% more energy than that (optimistically!), or even more, from the economy in order to build wind turbines. We certainly do need a massive crash program in renewables. But we should also have some honest discussion about what this involves — a level of the effort that will require the total mobilization of society and of which our political leaders seem completely ignorant. |
Will
renewables like wind and solar power help get us to a renewable energy
economy? At the recent