With its crater filled with turquoise blue water, its fumaroles from which steam, sulfur and muddy water boiling in the smell of rotten eggs gush out, the Krafla volcano is one of Iceland’s natural wonders, enthroned in the northeast from the island.
This is where an international alliance is preparing to drill more than two kilometers deep, directly into the volcano, in order to create the first underground magma observatory in the world, a Jules Verne project that has also energy targets.
Launched in 2014 and with a first drilling scheduled for 2024, this large plan estimated at $ 100 million is supported by scientists and engineers from 38 research institutes and companies in eleven countries including the United States, the United Kingdom and France.
Called “Krafla Magma Testbed” (KMT), it aims to reach a pocket filled with magma. Because unlike surface lava, molten rock miles deep is still unknown land.
“There is no such observatory and we have never observed underground magma, apart from three fortuitous encounters during drilling” in Hawaii, Kenya and Iceland, explains to AFP Paolo Papale, a vulcanologist at the Italian National Institute of Geophysics and Vulcanology and associated with the project.
The project aims at the same time at the progress in fundamental science, in the exploitation of the geothermal energy known as “super hot” as well as the prediction of volcanic eruptions and its risks.
“Knowing where the magma is is vital to being well prepared,” says Papale. “Without it, we are almost blind.”
The first phase of drilling, which is to cost $ 25 million, plans several exploration holes around and below the magma and is expected to begin in 2024.
The borehole, kept open, will make it possible to reach the magma and take samples.
It was following an accident that the idea was born. In 2009, to develop the capacities of the geothermal power station installed on Krafla since 1977, a borehole perforated a pocket of magma at 900 ° C at a depth of 2.1 kilometers.
Challenge
Smoke comes out to the surface, lava rises a few meters in the pipe, the drilling equipment is damaged. Fortunately, no one is injured, and vulcanologists now have within drill reach a pocket of magma estimated at 500 million cubic meters.
“This discovery has the potential to be a huge step forward in our ability to understand many different things,” said Paolo Papale, citing in particular the origin of continents, the dynamics of volcanoes and geothermal systems.
The accident also shows promise for Landsvirkjun, the national electricity company that operates the site.
Kilometers underground, the rock reaches such extreme temperatures that the fluids encountered are said to be “supercritical”, that is to say with intermediate behavior between the liquid and gaseous state.
The energy produced there is five to ten times greater than in a conventional well. During the 2009 accident, the steam rising to the surface reached an unprecedented 450 ° C.
Two supercritical wells would thus be sufficient to reach the power of 60 megawatts that the power station currently generates with … 18 conventional wells.
“Thanks to the project, we want to develop a new technology to be able to drill deeper and exploit this energy that has never been before,” ambitions Vordís Eiríksdóttir, executive director of geothermal operations at Landsvirkjun.
Drilling in such an extreme environment is a technical challenge: the materials must be adapted to resist the corrosion caused by the super hot steam.
The possibility of the operation triggering a volcanic eruption is a “natural concern” according to John Eichelberger, professor emeritus of geology and geophysics at the University of Alaska, but it is equivalent to “pricking an elephant with a needle”.
“A dozen holes have touched magma in three different places (in the world, editor’s note) and nothing serious has happened”, he pleads.