POWER HARNESSED FROM VOLCANOES?
POWER HARNESSED FROM VOLCANOES?
Science studies volcanoes for a while now but being able to do it up close is a challenge, even with modern technology. What about harnessing electricity from one?
Geothermal energy uses the heat trapped beneath the Earth’s surface to generate electricity. But the volcanic geothermal energy, resides in harnessing supercritical water – which is neither liquid, nor gas.
In August 2016, researchers within the Iceland Deep Drilling Project (IDDP) spent 168 days drilling into a volcano in the Reykjanes Peninsula, Iceland, dormant for the last 700 years. They were investigating the feasibility of volcano-powered electricity, as specified in a statement.
Geothermal energy is a major source of energy in Iceland – about 25 percent of the country’s electricity generated from tapping the Earth’s heat, according to the National Energy Authority of Iceland. And about 90 percent of the households are heated with geothermal energy.
THE GEOTHERMAL ENERGY REVOLUTION
While the depths of the geothermal field beneath the Reykjanes has not been explored until 2016, a record-breaking drill of 3 miles was completed on January 25, 2017. At this depth, the hole cannot enter the magma chamber but it did penetrate the rock surrounding it, measured to be about 800 degrees Fahrenheit.
Continuously drilling shafts over the years, in 2009, at Krafla, in the northeast Iceland, the IDDP reached a depth of only 2,100 m, before unexpectedly striking a pocket of magma intruding into the Earth’s upper crust from below, at searing temperatures of 900-1000°C.
A special report issued in 2007, detailed the engineering feats and scientific results that came from the decision not to the plug the hole with concrete – as in a previous case in Hawaii in 2007 – but instead attempt to harness the geothermal heat.
“Drilling into magma is a very rare occurrence, and this is only the second known instance anywhere in the world,“ said Wilfred Elders, a professor emeritus of geology at the University of California, Riverside (who co-authored three of the research papers in the Geothermics special issue with Icelandic colleagues.
The process implied cementing a steel casing into the well, while leaving a perforated section at the bottom, close to the magma. Heat was allowed to slowly build in the borehole, and eventually superheated steam flowed up through the well for the next two years.
“Amazing, to say the least, this could lead to a revolution in the energy efficiency of high-temperature geothermal projects in the future,” Elders added.
THE SUPERCRITICAL WATER
This new well offered superheated, high-pressure steam for months at temperatures of over 450°C – which was a world record, while the geothermal resources in the UK rarely reach higher than around 60-80°C.
The resulted magma-heated steam was measured to be capable of generating 36MW of electrical power. While compared to a regular 660MW coal-fired power station, it is rather modest, but definitely more than the 1-3MW of an average wind turbine. It comprises more than half of the Krafla plant’s current 60MW output.
Now the IDDP are looking for a further prize: supercritical water. At high temperatures and under high pressure deep underground, the water enters a supercritical state, being neither gas nor liquid. Harnessed correctly, this can increase the power output to about 50MW.
“If deep supercritical wells, here and elsewhere in the world, can produce more power than conventional geothermal wells, fewer wells would be needed to produce the same power output, leading to less environmental impact and improved economics,” IDDP researchers said in the statement.
The Geothermal Energy Association (GEA) found that only about 7 percent of the Earth’s geothermal power potential has been tapped – said the 2016 power production report. GEA predicts that the geothermal energy production will more than double by 2030.
