Sep 30 2008

Who's the Cleanest of Them All?

Posted by: Jonathan Marshall

There's no such thing as perfectly clean energy: even a person riding a bicycle generator exhales carbon dioxide. And once you factor in the energy and materials used to produce and transport wind turbines or solar panels, those renewable sources have their modest downsides, too.

So if our goal is to do the least damage to the environment, and in particular to climate stability, it's important to analyze all the lifecycle implications of our energy choices.

Benjamin K. Sovacool, a research fellow at the National University of Singapore, did just that in a recent issue of Energy Policy magazine. His ranking probably comes as no surprise, but his numbers highlight the enormous difference between alternative technologies.

In terms of grams of total lifecycle carbon dioxide emissions per kilowatt hour of electricity, here's how several major sources of energy stack up:

• Coal - 960
• Natural Gas - 443
• Nuclear - 66
• Solar photovoltaic - 32
• Wind (onshore)  - 10

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