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Geothermal Energy

The Past, Present, and Future of Geothermal

Written by Brian Hicks
Posted September 27, 2009 at 8:00PM

As the Senate prepares to consider the climate bill that Senators Barbara Boxer (D-Cal) and John Kerry (D-Mass) release Wednesday, Sept. 28, public focus will soon shift to the contentious topic of climate change and energy reform.

Emissions reduction legisltation will mean more momentum for renewable energy sources, and one of the brightest spots in the world of renewables is geothermal energy.

Geothermal energy is naturally generated in the earth's core (which is hotter than the surface of the sun) and presents itself as a clean, renewable and domestic source of energy, as it can never be shipped overseas.

In fact, according to the US Department of Energy, the first dry steam geothermal plant was built in Laderello, Italy in 1904. This plant has run flawlessly since that year and now provides power to about 1 million households.

Geothermal is an easy pick for Congress, but there are many different factors involved in a successful plant, including the type of plant best suited for each location.

Types of Geothermal Technology

One of the oldest and most efficient uses of geothermal energy is "dry steam geothermal" power plants. In these systems, steam (with no water) shoots up the wells directly from an underground reservoir and is then used to power the turbines of a generator which, in turn creates electricity. This is the oldest type of geothermal energy and is currently producing 10MW of electricity at "The Geysers" in California.

Flash-steam plants draw highly pressurized hot water from reservoirs in the earth, and then transfer it to low pressure tanks. The decrease in pressure causes the hot water to "flash" and quickly becomes steam that is then used to drive a turbine. Once the steam has cooled and condenses into water, it is then returned to the ground and is reused. Most geothermal plants today use this system.

Binary cycle geothermal power plants offer the chance to develop geothermal power where the ground has not traditionally been hot enough to produce steam. Here, moderately hot geothermal water is passed by a secondary fluid which turns to steam at a lower point than water. The secondary liquid then turns to steam and is used to drive the turbine.

The Next Horizon-EGS

Geothermal power has in the past only been cost efficient near fault lines in the earth's crust, more specifically, in America's West around Nevada, Idaho and California. This is where most of America's current geothermal power is generated, but now, with developments in technology, geothermal energy is becoming more deployable worldwide.

Enhanced Geothermal Systems(EGS) could extend the use of geothermal energy to almost anywhere...

In these systems, pressurized water is injected miles deep into the hot rock of the earth to create thousands of pathways for water to be heated to its flash point. This makes geothermal technology work almost exactly the same way as it does around more favorable locations and has vast potential.

EGS is an extremely attractive option, as it is reliable and can be used as base load power worldwide.

In fact, Dr. Jefferson Tester of the Massachusetts Institute of Technology says that geothermal energy has a potential to power our country 140,000 times over, using Enhanced Geothermal Systems. The United States currently needs about 100 exajoules to power it's daily needs. Tester believes that there is a potential to harvest 14,000,000 exajoules of geothermal energy nation wide.

People...and investors have begun flocking to this technology. Even internet mogul Google has invested more than $10.5 million into companies like Potter Drilling, AltaRock Energy, Inc and Southern Methodist Universty Geothermal Lab.

There was 2,957 MW of installed geothermal power capacity as of 2008 in the United States alone, and a total of 10,200 MW worldwide. Even with extremely conservative estimates, that total is expected to triple by 2020 to 32,592.

But if EGS develops as expected, those numbers could be multiples higher...

As the dwindling supply of traditional fossil fuels becomes more apparent, more and more money will flow into advanced green technology, and the upcoming debate in Washington will shape the way that money is spent and which industries will succeed.

With trillions of dollars and the future of our economy at stake, one can only hope that our elected officials serve us well by adopting the policy that best utilizes American technology, geography and resources. And I can say, without a doubt that geothermal will have a role to play in the realization of that goal, as 100 years of success is hardly debatable.

It appears that the Italians were at least 105 years ahead of the game. Their plant in Laderello has run flawlessly for over a century, outliving its creators and likely their children.

How many nuclear power plants can boast the same record?

None.

So the next time someone tells you that renewable energy can't be a viable energy option, point them in the direction of Laderello.
 
-Kyle Haas

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