Renewables: what we meant to say.

• Position: Letter to the editor

Thanks for your response to my previous letter [on renewables, Sept/Oct 2006]. Unfortunately I was hoping for a more substantive, less touchy-feely response to such an important issue. Are we to place all our eggs in the renewables basket simply on the basis of your declaratory statement that IEA "vastly underestimates the potential growth of renewable energy"?

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Clearly, there are examples of experts underestimating the growth of whatever new technology. But my concern is that this proves nothing. I could just as easily make the opposite argument. I could, for example, quote Paul Maycock who, as a Department of Energy expert in 1980, projected the cost of solar cells falling to under US$1 per peak watt in six years (Forbes, October 13, 1980). As you no doubt know, a quarter-century later, their cost is still about three times that price. Anyone making an investment decision at that time on the basis of that expert would have lost his or her shirt.

I was hoping that World Watch might provide researchers, funders, politicians, and planners with substantive arguments for why certain technological options are promising and should be supported. If it cannot, this might simply indicate that no technologies hold out the potential for economically, safely, and adequately meeting our future energy needs. But in this case, mankind (and World Watch) ought to be discussing the implications for the future state of the world of being in this predicament.

ALLEN INVERSIN

Riverdale, Maryland, U.S.A.

Chris Flavin and Janet Sawin respond (Editor's Note: see www.worldwatch.org/ww/renewables/ for accompanying documentation): Our apologies to Mr. Inversin for the brevity of our earlier reply to his letter, which came at a busy time. Our conclusion that renewable energy, combined with high levels of energy efficiency, is a robust alternative to fossil fuels is based on scientific and engineering studies that document the vast scale of the renewable energy resource base--including solar, wind, geothermal, and biological resources--as well as the rapid advance in energy conversion technologies now under way.

Wind power is a good example. A 1991 study by the Pacific Northwest National Laboratory found that land-based wind resources in just three states could theoretically meet all U.S. electricity needs, even with significant environmental, urban, and other exclusions. Since then, wind power technology has advanced significantly, and wind...