What is it?
Geothermal power — literally heat from the earth's subsurface — has not only been getting investor attention lately, but it can lay claim to being perhaps the oldest of renewable energy sources. It is also genuinely renewable, if managed well, and can provide constant supply (95 percent "capacity factor"), making it a potential base load (constant) power source — a key advantage over wind or solar, the current renewable darlings.
The first geothermal generator kicked into action July 4, 1904 at a dry steam field in Larderello, Italy, and is still operational. In the US, the Idaho state capital complex in Boise has been heated by geothermal almost as long. Geothermal currently supplies just one percent of the world's energy demand, but there is considerable growth potential.
Geothermal energy is also clean, safe and competitive in price to wind, costing between 4.4 to 7.5 cents per kilowatt hour. The Energy Policy Act of 2005 was the first time the federal government treated geothermal as a renewable energy, extending production tax credits ($0.019 per kWh), which further reduced costs.
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