Photograph by Brynjar Gauti, AP
An ash cloud billows from southern Iceland's sub-glacial Eyjafjallajökull volcano on April 16, 2010, signaling an escape of the heat inside the Earth that is drawing renewed interest worldwide as an energy source.
Almost all of Iceland's building and water heating comes from geothermal energy, which also provides about a third of the nation's electricity. But nobody has figured out how to harness that energy safely when it breaks through the surface as an active volcano. That's too bad, because thermal emissions coming from Iceland's Eyjafjallajökull volcano in March 2010, during the first of two eruptions, quickly reached 1 gigawatt , and later peaked at 6 gigawatts, says Ashley Davies, a volcanologist at NASA's Jet Propulsion Laboratory in Pasadena, California.
One gigawatt is the capacity of a large power plant, like the Hudson Generating Station across the Hudson River from Manhattan in Jersey City, New Jersey, which serves 750,000 households with a mix of coal, natural gas, and oil. Six gigawatts is greater than the capacity of any U.S. electric plant except for the huge Grand Coulee hydroelectric plant.
And that's just a small portion of the total thermal output in the volcano's 2010 eruption. It does not account for mechanical energy—the accompanying earthquakes and explosive blasts—or additional heat in the erupting lava. NASA measured the volcano's thermal output using satellite imagery, which it also employs to gauge volcanoes elsewhere in the solar system. Some of those other-world volcanoes dwarf those on Earth, Davies adds, including one on the Jupiter moon Io whose 2001 eruption radiated 78 terawatts of heat. Think of that as 78 times the total capacity of all the power plants in the United States.
Over an hour, that would be equivalent to the energy in about 46 million barrels of oil— about half the amount consumed around the world every day.
Back at Iceland's Eyjafjallajökull, another part of the volcano underwent a much larger eruption in April 2010. That eruption occurred under an ice cap that hid much of its power from the NASA satellite, which still measured 60 megawatts of radiated power. Over the course of an hour, that would be equivalent to the energy output of 1,648 gallons (6,238 liters) of gasoline—the amount that an average U.S. motorist would have to buy over four years to fuel a car that drives 10,000 miles annually.
That eruption's interaction of lava with ice generated clouds of steam and ash that groun
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