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Fortnightly Magazine - March 1 1996

U.S energy needs because the costs are not comparable.

The costs quoted for PVs are the costs of the electricity produced when the cells operate under ideal, sunny conditions. Consumers, however, require their electricity on demand, 24 hours a day, and the cost of reliable, dispatchable, stand-alone PV power to meet that demand can reach 10 or more times the quoted PV power costs. Here's why. First, the ideal sunny conditions that underlie PV costs occur roughly 8 hours per day. At night PVs produce no power at all, so means must be provided to satisfy load demands during long daily periods of no PV generation. Lastly, when it is cloudy, PV power output can drop to 20 to 40 percent of name-plate ratings, again requiring additional means to satisfy electric load requirements.

Storage can provide reliable power at night and when it is cloudy, but storage adds cost. Further, added storage requires additional PVs to charge the storage and maintain the name-plate power level of the original PV array. Since many cloudy days in a row occur at different times in most parts of the country, it is often necessary to multiply the investment in PV cells by a factor of 10 or so to charge the storage during clear days. Thus, the seemingly attractive, quoted PV costs must be increased many fold in most U.S. locations to yield the true cost of reliable, stand-alone electric power. Some argue that conventional power plants could be held in reserve to provide power when PVs operate at reduced or zero power. That idea works in principle, but would increase the cost of power by a factor of roughly two or more, because it forces a costly capital investment to sit idle waiting for periods of clouds or night to provide backup power. Because the public is not likely to accept such cost premiums, stand-alone PVs (as we currently practice the technology) will make a relatively small contribution to national energy needs.

Other Renewables. These arguments apply also to the other intermittent renewables, such as wind and solar thermal. Hydro and biomass electricity, with their built-in storage, have their own particular problems, which will limit their expansion in the next decade or so.

The bottom line? Renewable technologies as we know them today cannot collectively provide more than maybe 10 percent of U.S. electricity production, and I expect even that day will be a long time in coming. These fundamental realities have not been widely recognized and discussed. Many environmentalists and public officials have been oversold and will be disappointed in the years ahead.

Fuel Cells. Decreasing costs due to the development of new technologies, particularly proton exchange membranes, may have poised fuel cells to enter the electric power market as distributed

electricity generators in the next 5 to 10 years. However, because the U.S. electrical power system is so massive, and because distributed generation comes in inherently small packages, it will likely take decades for fuel cells to have a noticeable impact on the U.S. energy system. Notwithstanding these macro effects, fuel cells