Friday, August 20, 2010

Geothermal Energy and Entropy

As fossil fuels are starting to become scarcer and harder to obtain, we human energy hogs are finding ever better ways to convert forces of nature into sources of household energy. We have begun to harness wind, waves and sun and in some parts of the world, we have started to extract heating and cooling BTUs from the Earth.

Places like Iceland, where volcanic heat is just below the surface, this geothermal energy has been used for centuries. Even in Africa I have stumbled over project of this type while hiking in Hell's Gate National Park near Lake Naivasha in Kenya.

Olkaria I Geothermal Power Plant in Kenya, 1988

Just yesterday I heard a radio program on how the state of California is sponsoring geothermal initiatives (Full Steam Ahead for Geothermal Plans, NPR). While generally boosterish, the report did acknowledge bore holes literally running out of steam, issues with small earthquakes, and boreholes collapsing. Indeed, a quick survey of these problems brings up articles from the web. The running-out-of-steam problem in particular piqued my interest. I had thought before generating geothermal energy is closely tied to the second law of thermodynamics. As the air is heated, the earth in the bore hole is cooled. Eventually, and admittedly probably after many millions of years, the temperature of the earth and of the earth will be the same.

I thought about this on my way to work and forgot about it till I drove home, again with my radio tuned to NPR. And wouldn't you know it, a certain Cedric Villani won a mathematics award (the Fields Medal) for calculating the rate at which entropy increases in the world.

This was too odd to simply ignore. And when my friend Paul told me he wanted to install a geothermal system in his house, I know I needed to take another look.

A search for geothermal and entropy brings indeed quite a few hits and leads to articles such as this one: "Entropy (not Energy) is the Issue, New Earth Rising"

I don't know much about physics or math but I am glad that my musings are not necessarily original.

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