Enhanced Geothermal Systems - The "Killer App" of the Energy World
Google surprised the audience at the National Clean Energy Summit in August by pronouncing that “enhanced” geothermal energy could be the “killer app” of the energy world. In September, Google and General Electric jointly announced an effort to more fully develop this potentially unlimited resource.
What exactly is “enhanced” geothermal energy? Why has it excited such giants as General Electric and Google? And, will it live up to expectations?
Traditional geothermal energy relies on naturally occurring pockets of steam and hot water beneath the earth. Geothermal power plants on the surface use the steam from 1 to 2 miles below the surface to run turbines and generate electricity. In order to be economic, large geothermal plants are usually built where the heat is relatively near the surface and where the temperatures of the hydrothermal resources are generally warm (between 300 and 700 degrees Fahrenheit). These plants produce, on average, for about 30 years and, depending on their location, are competitive with the prices from traditional fossil fuels plants. However, large scale geothermal resources seem quite hard to come by or the resources are located at uneconomic depths. Consequently, traditional geothermal power plants produce less than .0035 of total electric generation in the US and less than 1 percent world-wide.
“Enhanced” geothermal however, taps into the earth’s unlimited hot rock. Those rocks are then fractured, water is circulated through the system, and the resulting steam is used to produce electricity in a conventional turbine.
Continue Reading...The Addition of SF6 to DoD's Emerging Contaminants Action List
After years of controversy over the use of Sulfur Hexafluoride (SF6) in both the public and private sectors, the Department of Defense has added SF6 to its emerging contaminants action list – notably ahead of any potential domestic greenhouse gas regulation. DoD believes that it is necessary to develop risk management measures, such as replacement options and cleanup technologies, in order to ensure that they avoid future problems and expense.
SF6 has military uses in radar systems, such as Airborne Warning and Control Systems (AWACS), helicopter rotor-blade leak tests, discharge testing in fire suppression systems, electrical switch gear, and propulsion systems. But, more importantly, the addition of SF6 to the DoD action list will likely result in reduced use and availability. Defense acquisitions, research, and development will bear the greatest burden.
According to the Intergovernmental Panel on Climate Change (IPCC), SF6 is the most potent of the six main greenhouse gases with a global warming potential (GWP) of 23,900 times that of CO2 over 100 years.* Although the concentration of SF6 in the atmosphere is lower than that of other GHGs, SF6 emissions are still a major problem because the GWP and atmospheric lifetime (3200 years) are so much higher. This means that that implementing new practices to reduce the use of one pound of SF6 is equivalent to retiring 11 tons of carbon.
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