The Science of Sustainability

Producer's Notes: Geothermal Heats Up

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Geothermal power production could significantly add to the electric power generating capacity in the United States." That's the attention-grabber at the top of a September 2008 press release from the U.S. Geological Survey announcing the release of their first geothermal resource assessment in 30 years.

When I first began researching this story for QUEST, I was surprised that I hadn't heard more about geothermal power. It's never lumped into that renewable energy laundry list that's recited by politicians and journalists alike — you know, "…solar, wind, hydroelectric and biofuels". But it turns out that geothermal energy has really great potential.

To start, it's reliable. Geothermal is base load power, which means that the plants generate power at a constant rate around the clock. In fact, geothermal plants often have capacity factors of 86-95%, well above traditional base load generation such as coal.

It's clean. Geothermal power plants give off little or no sulfur compared to fossil fuel-fired power plants and they emit no nitrogen oxides. Emissions of CO2 per megawatt-hour are extremely low or absent for the newer flash plants. A typical geothermal plant may produce 1 lbs. of CO2 per MW hour. This figure compares with 1030 lbs. per MW hour of CO2 for a natural-gas fired plant, 1600 lbs. per hour of CO2 for an oil-fired plant, and 1820 lbs. per MW hour for a low grade coal-fired plant.

And, if the USGS assessment is accurate, and it probably is, geothermal power is abundant. According to the study:

"the power generation potential from identified geothermal systems range from 3,675 MWe (95% probability) to 16,457 MWe (5% probability); the power generation potential from undiscovered geothermal systems range from 7,917 MWe (95% probability) to 73,286 MWe (5% probability); and the power generation potential from Enhanced Geothermal Systems range from 345,100 MWe (95% probability) to 727,900 MWe (5% probability)."

So, what's wrong with it? As we touched on in the TV segment, there are several little drawbacks that no doubt should be considered. These include induced seismicity (little earthquakes that are triggered by geothermal developments), the initial expense of geothermal exploration and development, and the challenges of connecting the electricity generated by a geothermal plant to the grid at a point where there is sufficient available capacity to sell the electricity.

However, I was never really able to find a strong reason why geothermal energy should not be in everyone's renewables laundry list. And considering Obama included geothermal energy in his list during his last debate against John McCain, I would imagine we will all be hearing more and more about geothermal energy development in the months to come and beyond.


Watch the Geothermal Heats Up television story report online. And don't miss the steamy, behind-the-scenes photos for this story.


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Category: Energy, Engineering, Environment, Geology, Partners, Television

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Amy Miller

About the Author ()

Amy Miller is the Supervising Producer and Partner at Spine Films, a boutique independent production company specializing in hard science factual television. Prior to joining the Spine team, Amy worked for six years at KQED (PBS) in San Francisco as the Series Producer of QUEST, a multimedia science and environment series. It was at KQED that she was finally able to merge her lifelong passions for science and storytelling. Originally from Iowa, Amy grew up in Colorado then landed in San Francisco in 1991. She studied biology and film production at University of Colorado and San Francisco State University, and since graduating in 1995, she has worked as a camera assistant, documentary filmmaker, TV producer and correspondent on a variety of cable and public television shows including two other KQED series, "Spark" and "Independent View". For her work in television, she has earned ten regional Emmy awards, two AAAS Kavli Science Journalism awards, and a Society of Professional Journalists Excellence in Journalism Feature Writing award.
  • HighSierraGuy

    Could you expand further upon what is done with the mercury, lead, cadmium etc generated waste? Do they recycle this back into the aquifer by re-injection or dispose off site? If the former are drinking water sources (and/or potential sources) put a risk of contamination (especially now that the emphasis is on man created fracturing)?

    Thank you,
    High Sierra Guy

  • Stan

    This article is proof that geothermal has come a long ways from the simple heat pump.