Blue Marble - April 2008

Time's Breaking News: Ethanol Is Bad

| Wed Apr. 2, 2008 2:19 PM EDT

Time's cover story this week debunks the idea that ethanol holds the promise of clean energy. But that's old news, right? Back in November, Mother Jones' "The Ethanol Effect" broke down America's newest cash crop, kernel by kernel. It reveals that growing one acre of corn requires 110 gallons of gasoline, and that ethanol's net energy output is far less than that of conventional fuel. Check out all the raw numbers here.

—Celia Perry

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Cheaper, More Reliable Solar?

| Tue Apr. 1, 2008 10:34 PM EDT

feature_solar1.jpg It's appearing in the form of solar thermal. Instead of converting sunlight to electricity, solar thermal, also called concentrated solar power, harness the sun's energy by converting sunlight to heat with the help of mirrors. This according to a great piece in the current Geotimes, magazine of the American Geological Institute. Some plants use curved mirrors, known as parabolic troughs, to focus sunlight onto pipes filled with circulating oil that circulate and heat steam to power a standard generator. In another system, solar power towers use large fields of sun-tracking mirrors that focus solar energy onto a receiver on top of a central tower. The intense energy concentrated onto the tower produces temperatures up to 2,732 degrees Fahrenheit, which then heats water to produce steam and drive a turbine to generate electricity. Many newer plants use insulated tanks filled with molten salt for heat storage, which provide power on cloudy days and at night—addressing the ephemeral nature of solar power.

Seems the searing West just might be the place for a lot more solar thermal.

Julia Whitty is Mother Jones' environmental correspondent, lecturer, and 2008 winner of the Kiriyama Prize and the John Burroughs Medal Award. You can read from her new book, The Fragile Edge, and other writings, here.