Magma Power for Geothermal Energy?

By Andy Fell, UC Davis   |   February 23, 2011   |   1 Comment 

California, USA -- When a team of scientists drilling near an Icelandic volcano hit magma in 2009, they had to abandon their planned experiments on geothermal energy. But the mishap could point the way to an alternative source of geothermal power.

"Because we drilled into magma, this borehole could now be a really high-quality geothermal well," said Peter Schiffman, professor of geology at UC Davis and a member of the research team along with fellow UC Davis geology professor Robert Zierenberg and UC Davis graduate student Naomi Marks. The project was led by Wilfred Elders, a geology professor at UC Riverside.

A paper describing geological results from the well was published this month in the journal Geology.

When tested, the magma well produced dry steam at 750 degrees Fahrenheit (400 degrees Celsius). The team estimated that this steam could be harnessed in a 25 MW capacity plant.

That compares to 5 to 8 MW produced by a typical geothermal well, Elders said. Iceland already gets about one-third of its electricity and almost all of its home heating from geothermal sources.

The team was drilling into the Krafla caldera as part of the Iceland Deep Drilling Project, an industry-government consortium, to test whether "supercritical" water -- very hot water under very high pressure -- could be exploited as a source of power.

They planned to drill to 15,000 feet -- more than two miles deep-- but at 6,900 feet, magma (molten rock from the Earth's core) flowed into the well, forcing them to stop.

The composition of magma from the borehole is also providing insight into how magmas form beneath Iceland, Schiffman said.

The team included researchers from two Icelandic power companies, HS Orka hf andLandsvirkjun Power; Iceland GeoSurvey; the U.S. Geological Survey; Stanford University; New Mexico Institute of Mining and Technology; and the University of Oregon, Eugene; as well as UC Davis and UC Riverside.

The work was funded by the National Science Foundation and the International Continental Scientific Drilling Program.

Andy Fell is a science writer at UC Davis.

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glenn-doty-175949 February 23, 2011 The idea sounds great - this solves the most significant problem with enhanced geothermal energy (EGS) by using the convection of liquid flowing rock to transfer heat rather than the conduction of hard rock to transfer heat. For those that are not aware, EGS rapidly depletes the rock strata of its high temperatures, and the rock strata must be continually re-fracked to provide new high-temperature channels for the water/steam to flow through for high-heat transfer. This is because the water strips heat from the rock faster than the conduction through the rock can replace that heat. HOWEVER, there's a problem with magma. That boils down to materials science. Liquid rock would quickly cap whatever channels for water/steam were used for the heat exchange, and any closed pipe that was sunk into 1000 K liquid would suffer such high attack combined with such drastic material weakening that there would be a very short lifespan. Magma is the ultimate dream for EGS, but a great deal of development would be required in order to figure out how to economically tap that resource. I wish them luck, but I would advise everyone not to expect a magma-well EGS system in their neighborhood soon.