New Avenues for Renewable Energy in Colorado

Geothermal energy isn't a word that's normally associated with Colorado. Sure, we have hot springs scattered throughout the southwestern quadrant of the state, but there's nothing like the +300°F temperatures normally associated with geothermal energy production. According to a new report by the Colorado Geological Survey, however, that impression may be in need of some serious revision.

Colorado has more geothermal resources than previously thought and can eventually use them as an alternative for fueling power plants, a recent state study found, Colorado officials said on Thursday.

Among U.S. states, Colorado ranks fourth with nine potential sites for geothermal power development, more than previous estimates, said Matt Sares, deputy director for the Colorado Geological Survey (CGS). The three states with more current or potential geothermal energy sites are also in the U.S. West - California, Nevada and Utah, Sares said.

Colorado has no geothermal power production. Sares said it is difficult to say when production may start, though it could be within a decade, depending on how soon companies decide the development will be fruitful, he said.

Does this mean that the ground temperature is higher than had previously been believed? Not exactly. The Montrose Daily Press notes that
[o]ne test hole near Ouray suggests that the earth's temperature rises nearly 190 degrees Fahrenheit per kilometer of depth. A data point near Rico holds the potential for a slightly hotter gradient.

While the technology required at some plants around the country require high-temperature waters of at least 347 degrees, recent technology would allow plants to use water with temperatures as low as 194 degrees, according to the U.S. Department of Energy.

This technology is the binary-cycle geothermal power plant. Rather than running the plant's turbines directly off of the vaporization of high-temperature, pressurized water extracted from the Earth's crust, binary-cycle power plants instead use the water to vaporize another fluid (often a hydrocarbon) with a lower boiling point; it is the high-temperature vapor of this second fluid that then drives the power plant's turbines. While such a design is more complicated than a typical geothermal power plant, it has the advantage of being able to operate at much lower water temperatures. Just like those now believed to prevail in the southwestern mountains.

It's easy to get excited about news like this, but there are important caveats. As noted above, Colorado currently has no geothermal power plants, and it will be years before such systems can come online assuming that investors and interested energy companies can be found. The United State's geothermal resources are also relatively small, and are unlikely to ever provide more than 10% of our energy needs. Still, only 0.36% of the nation's electricity is currently produced using geothermal resources, so there's a lot of room for growth.

Given that Colorado is already ideally situated for exploiting both wind and solar power, the addition of significant geothermal resources is icing on the sustainable cake. The question now is if Colorado will prove to have the political willpower and economic savvy to position itself on the forefront of renewable energy production. Despite recent political dawdling, I'd say that the state's energy prospects are still best described as bright and green.

(Tip of the hat to Coyote Gulch for originally highlighting this story.)