Scientists in Iceland believe they have discovered what could lead to a revolution in how we harness energy – with molten lava deep beneath the Earth's surface.
Researchers working on the Icelandic Deep Drilling Project (IDDP) were drilling holes five kilometres into the ground when they accidentally hit a pocket of magma that was intruding into the Earth's upper crust.
According to a report in The Conversation, instead of filling the hole up with cement, the team decided to try to harness the heat generated from the molten rock and turn it into energy.
Wilfred Elders, professor emeritus of geology at the University of California Riverside, said: "Drilling into magma is a very rare occurrence, and this is only the second known instance anywhere in the world."
The magma was scorching hot – at between 900C and 1000C. The team built the borehole by cementing a steel casting into the well and leaving a perforated section at the bottom. Heat then built up the hole and superheated steam flowed up for the next two years.
Elders said the results were "amazing" and that their findings "could lead to a revolution in the energy efficiency of high-temperature geothermal projects in the future".
The magma heated steam generated 36MW of electrical power – about a 20th of a typical coal-powered station, but far more than the average wind turbine, which puts out between 1 and 3MW.
"Essentially, IDDP-1 is the world's first magma-enhanced geothermal system, the first to supply heat directly from molten magma," Elders said.
In Iceland, volcanoes are dormant most of the time but can be activated through shifts in the Earth deep underground. Gillian Foulger, professor of geophysics at Durham University, said drilling should not cause an eruption.
"They can become very dynamic, raised in pressure, and even force magma to the surface. But if it's not activated, then there's no reason to expect a violent eruption, even if you drill into it" Foulger said.
"Having said that, with only one experimental account to go on, it wouldn't be a good idea to drill like this in a volcanic region anywhere near a city."
Around 90% of Iceland's energy comes from geothermal sources, with the power harnessed from pumping cold water into hot dry rocks around four kilometres below the surface. This type of energy has been expensive and unreliable in other parts of the world, however.
Elders said that while their experiment suffered setbacks, the process was "instructive".
Fougler said the scientists did well to harness the opportunity of hitting lava instead of abandoning the project.
"Most people faced with tapping into a magma chamber would pack their bags and leave. But when life gives you lemons, you make lemonade."