Monday, July 09, 2012

A Skeptic Looks at Alternative Energy - IEEE Spectrum

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Without these subsidies, renewable energy plants other than hydroelectric and geothermal ones can't yet compete with conventional generators. There are several reasons, starting with relatively low capacity factors—the most electricity a plant can actually produce divided by what it would produce if it could be run full time. The capacity factor of a typical nuclear power plant is more than 90 percent; for a coal-fired generating plant it's about 65 to 70 percent. A photovoltaic installation can get close to 20 percent—in sunny Spain—and a wind turbine, well placed on dry land, from 25 to 30 percent. Put it offshore and it may even reach 40 percent. To convert to either of the latter two technologies, you must also figure in the need to string entirely new transmission lines to places where sun and wind abound, as well as the need to manage a more variable system load, due to the intermittent nature of the power.

The matter of affordable costs is the hardest promise to assess, given the many assorted subsidies and the creative accounting techniques that have for years propped up alternative and renewable generation technologies. Both the European Wind Energy Association and the American Wind Energy Association claim that wind turbines already produce cheaper electricity than coal-fired power plants do, while the solar enthusiasts love to take the history of impressively declining prices for photovoltaic cells and project them forward to imply that we'll soon see installed costs that are amazingly low.
But other analyses refute the claims of cheap wind electricity, and still others take into account the fact that photo­voltaic installations require not just cells but also frames, inverters, batteries, and labor. These associated expenses are not plummeting at all, and that is why the cost of electricity generated by residential solar systems in the United States has not changed dramatically since 2000. At that time the national mean was close to 40 U.S. cents per kilowatt­-hour, while the latest Solarbuzz data for 2012 show 28.91 cents per kilowatt-hour in sunny climates and 63.60 cents per kilowatt-­hour in cloudy ones. That's still far more expensive than using fossil fuels, which in the United States cost between 11 and 12 cents per kilowatt-hour in 2011. The age of mass-scale, decentralized photovoltaic generation is not here yet.

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