In 2009, when the first borehole in a series of wells was drilled as part of the Icelandic Deep Drilling Project (IDDP) in Krafla, northeast Iceland (Figure 5), it unexpectedly penetrated into magma with a temperature of between 900C and 1,000C at a depth of only 2,100 meters (m). Further investigation of the borehole, IDDP-1, has led to the development of a unique geothermal project that supplies heat directly from magma.
“Drilling into magma is a very rare occurrence anywhere in the world, and this is only the second known instance, the first one, in 2007, being in Hawaii,” noted Wilfred Elders, a professor emeritus of geology at the University of California, Riverside who edited a special issue of the international journal Geothermics that was dedicated to the scientific and engineering findings arising from a two-year-long observation period at the unique borehole.
Bearing part of the substantial costs involved, the IDDP—comprising HS Energy, Reykjavik Energy, Iceland’s National Power Co., and the National Energy Authority of Iceland—pumped cold water into the hole to fracture rock near the magma and create high permeability. Next, they cemented a steel casing into the well that was perforated in the bottom section closest to the magma. Then, they allowed the hole to heat slowly. Eventually, high-pressure steam at temperatures of more than 450C, a measured output that was sufficient for 36 MW, was allowed to flow out of the hole for two years until July 2012, when it was closed due to a valve failure.
According to Elders, the feat of being able to drill down into the magma despite difficulties—and to control it—is impressive. Perhaps more importantly, the well, which created a world record for geothermal heat, produced steam (Figure 6) that could be fed directly into National Power’s 60-MW Krafla geothermal power plant near the Krafla Volcano. The team was also able to cope with a “difficult chemical composition of steam” from the well with “simple countermeasures.”
|6. Not just hot rock, magma. This image shows the flow test of the IDDP-1 well. Courtesy: Kristján Einarsson|
The IDDP-1 experiment demonstrated that a high-enthalpy geothermal system can be successfully created this way, he said. “This unique engineered geothermal system is the world’s first to supply heat directly from a molten magma.”
Around the world, several large-scale field projects that use enhanced geothermal systems (EGS)—an engineered heat exchanger designed to extract geothermal energy by fracturing hot rock at depths of 4 kilometers or more—have reached varying degrees of success. Only one project—the 2007-commissioned 3.2-MW Landau project in Germany—has sustained commercial production rates. EGS has been stalled by a variety of issues, foremost among them an exponentially higher power cost than for fossil-fueled generation, owing to expenses associated with drilling of deep geothermal wells, experts say.
The Krafla experiment was not without setbacks that “tried personnel and equipment throughout,” Elders said. Much remains to be done. The next steps entail repairing the IDDP-1 well—which is currently “unstable”—or drilling a new similar hole. The IDDP could drill the next borehole, IDDP-2, in southwest Iceland at Reykjanes between 2014 and 2015.
—Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)