Daily Science Dose

The other night, my boyfriend brought up geothermal energy. Now, he is a pretty smart guy, but even he did not quite know the full extent of what is geothermal energy and all its potential. Than I ran across a post on Inhabitat that covered the new geothermal plant that is being built in New Mexico, so I figured maybe I should write a little something on geothermal for all of my wonderful, smart and attractive readers.

Geothermal energy pertains to the heat (which is energy, remember) that comes from the interior of the Earth. Usually what happens in geothermal (and nearly all electricity-producing generation plants) is that the heat that comes from the Earth is used to heat water, which turns to steam and drives turbines. When the turbines move, they move a generator, and by the magic of kinetic energy, voila, you create electricity. It’s very basic, and as an example, coal and nuclear power plants run on the same principle, but instead of using an already existing heat source, materials are combusted to create the heat to make steam.

If you remember your plate techtonics from science class, you must recall that our planet is literally sitting on top of molten rock that is extremely hot. It is true that certain parts of the planet, i.e. Earth’s crust, are closer to that molten rock than others. Remember the Pacific “ring of fire?” It is at these plate boundaries that you find the interior of the Earth is closer to the surface, and therefore available to us humans that can harness that heat.

The US Department of Energy has put out some numbers on the potential geothermal energy available in the United States. Shallow geothermal sources could provide as much as 120,000 MegaWatts of electricity. If 1 MW can provide electricity for 1,000 people, the full potential of just the shallow geothermal sources could provide electricity for 120,000,000 people. That is almost half the population of the United States.

Sidenote: During Barack Obama’s speech before the DNC the other night, when he talked about clean coal and nuclear power, I was shouting “geothermal” at the television. My neighbors must think I am crazy.

Well, now the real trick is getting more power out of geothermal sources. This refers to using lower temperatures, which are easier to tap into because these temps are closer to the surface and therefore requires less drilling deep into the Earth. An outfit in Utah, Raser Technologies, has developed a way to use lower temperatures to heat a liquid with a lower boiling point to turn the turbines. I cannot find the specifics on the Raser website, but hey, they don’t want to give away their trade secret before they can make money on it first, right? What is important is that by finding a way to get heat out of lower temperatures increases the amount of available geothermal energy that we can put into the power grid.

Back in April, I wrote a post for Celsias about McDonalds’ foray into geothermal heating and cooling systems. Not many people are hip to the fact that we can use the constant temperature below the earth’s surface to regulate the temperatures in our homes, schools, businesses, et cetera. This type of geothermal “energy” entails drilling maybe 200 to 300 feet down into the ground, and running some pipes down there, pumping water through those pipes and depending on what season you are in, the constant temperature of the Earth at that depth can act as a heat sink or a cooling pump. This type of heating and cooling system has been around since the 1940’s, but as the US just loves its fossil fuels, it has not been looked at in the manner it should be. I know I would love to not have to pay my heating bill this winter or any other winter…

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