It's not often that an idea that's initially deemed a failed experiment ends up ultimately being hailed as a breakthrough. But that's exactly what happened when, five years ago, a team of scientists in Iceland, drilling deep within the Earth’s crust, hit upon molten rock. Not only was it not what they were looking for at the time, but it also meant they had to abandon their quest to locate a reservoir that was rumored to contain a form of water so hot that it existed in a state somewhere between a normal liquid and a gas.
The implications of unearthing such an energy-dense liquid would have been huge. Water that's been heated to a "supercritical" state, with temperatures as high as 1,100 degrees Celsius, is only possible where there's a sufficient buildup of pressure and heat. The lab is one place where scientists have been able to recreate such conditions. But if it were produced naturally somewhere, an icy geothermic hotbed like Iceland would be a good bet, so the thinking goes.
Over the course of more than a decade, the Icelandic government, along with an international consortium of energy firms and scientists have poured over $22 million into figuring out whether it's possible to tap into a potentially abundant resource that packs 10 times the amount of energy as heated steam. The hope was that someday geothermal plants will be able to pipe this immense, yet clean power source to not only local homes and businesses, but also to countries like England and other coal and gas-dependent nations nearby.
Thus the Iceland Deep Drilling Project was conceived, in part, as an effort to position the tiny volcanic island of about 320,000 residents as a primary supplier of renewable energy. However, what made the unsuccessful drilling incident especially demoralizing was timing, as it occurred amid a deep economic crisis. With the near collapse of the country's central banking system, easy access to a virtually unlimited supply of geothermal energy, used to run 90 percent of households, was one of the few remaining inherent riches that officials felt could help fuel a recovery.
Still, accidentally striking underground magma didn't turn out to be total loss, as the researchers would later discover. At the bedrock of a volcano, heat trapped within molten rock burns at a consistent 900 to 1,000 degrees Celsius. This is important since much of the viscous substance's potency is lost the moment it flows out from the tip of a volcano in the form of lava, with the atmosphere exerting a cooling effect that alters the molten rock's composition significantly. The problem, now, was that striking magma is such a rare occurrence (it's only happened once in Hawaii), researchers haven't had much opportunity to work out a reliable method to tap its vast potential. Extracting usable energy first required that water reserves somehow collect at the site. And if that happened, the IDDP team would need to somehow fashion a system that's both resilient and capable of drawing steam from the well.
In a surprising report, published in the journal Geothermics, the researchers detailed exactly how they managed to accomplish this. Upon discovering a natural reservoir of rainwater that, over time, seeped into the crevices right above the magma flow, the IDDP team, led by geologist Guðmundur Ó. Friðleifsson, was able to successfully test out a custom-built transport system designed to funnel the hot liquid as it rose up. According to The Conversation, this is how the scientists came up with their so-called magma-enhanced geothermal system:
This meant cementing a steel casing into the well, one with a perforated section at the bottom closest 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.
[Wilfred] Elders [a geologist at the University of California in Riverside and co-author of the paper] said that the success of the drilling was “amazing, to say the least,” adding: “This could lead to a revolution in the energy efficiency of high-temperature geothermal projects in the future.”
The superheated steam that was brought to the surface was recorded at over 450 degrees Celsius—a far cry from supercritical liquids, but still the highest temperature at which steam-generated electricity has been been produced, according to the authors. For perspective, geothermal plants that pump water into underground wells to generate steam, produce power at temperatures of about 180 degrees Celsius. The amount of electricity generated at a plant depends on a number of variables, including how much water is being heated and funneled per minute and how efficient the system is at converting that energy to electricity. The well alone, which has a potential electrical output of 36 megawatts, produces more than half of the combined output of the 33 boreholes located at the nearby Krafla Power Station and enough to power roughly 9,000 homes at any given moment. It still pales somewhat in comparison to 660-megawatt coal plants, though.
So what's next? Well, there haven’t been any confirmed deals to build a geothermal station atop the well—at least not yet. But the fact that scientists were able to generate electricity via a volcanic substance should be taken as an encouraging sign. They also haven’t given up on their more exotic pursuit to mine for those elusive pockets of supercritical fluid. The team has already tagged a location in southwest Iceland for the next phase of the project. IDDP-2, scheduled for later this year, aims to drill a borehole five kilometers deep in search of even hotter sources of power.