Catalyst Spring 2013


Wind Power's Potential Is Real

The fall 2012 Catalyst article on renewable energy, energy ["Will Congress Take the Wind Out of Our Sails?"] . . . highlights propaganda issued by the American Wind Energy Association. . . . For example: "Wind capacity has tripled to more than 50,000 MW—enough to power nearly 13 million homes and retire 44 typical coal-fired plants." This would be wonderful if it were true, but the actual performance of wind turbines is closer to 30 percent of capacity, so the claim is theoretical, not actual, and therefore misleading.

Douglas Zweizig
Evansville, WI


The author responds:

The U.S. wind power fleet did have an average capacity factor of 34 percent in 2011 (that is, it generated about 34 percent of the maximum electricity it could produce if it operated at full power year-round). According to government data, U.S. wind capacity reached 50,000 megawatts (MW) last August. With a 34 percent capacity factor, wind would generate about 149 billion kilowatt-hours of electricity per year—roughly equivalent to 13 million homes using 11,500 kilowatt-hours of electricity (the national yearly average).

In 2009, U.S. coal-fired power plants had an average capacity factor of 64 percent, which means it takes 1.9 MW of wind to generate the same amount of electricity as one megawatt of coal. Thus, 50,000 MW of wind capacity could replace 26,563 MW of coal capacity—roughly equivalent to 44 typical 600 MW coal plants.

Steve Clemmer, director of research and analysis,
UCS Climate and Energy Program



LEDs: As Green as Advertised?

I read your article about LED lightbulbs [“How It Works,” Fall 2012]. I have heard they have no mercury, but contain semiconductors and must be disposed of in the same way you would dispose of a computer. I see no mention of this on the packaging.

Bruce Skud
Newburyport, MA


The author responds:

All lighting technologies contain materials that can contaminate the environment if disposed of in landfills. A forthcoming study by Pacific Northwest National Laboratory found that light-emitting diode (LED), incandescent, and compact fluorescent lightbulbs (CFLs) contain elements such as antimony, chromium, copper, or zinc at levels high enough to qualify as hazardous waste in the state of California (which has regulations more stringent than the federal government’s). That’s why it’s best to recycle used LED bulbs; contact the manufacturer or visit to find recycling programs near you.

The study also concluded that electricity consumption is by far the largest contributor to a bulb’s lifetime environmental impact. Because LED bulbs use about 75 percent less electricity than incandescents to produce the same amount of light, last about 12 to 25 times longer, and do not contain mercury like CFLs, they have the lowest environmental impact of the three main lighting technologies.

Heather Tuttle, editor