Fearless Icelanders to Drill Into Magma Chamber
Image: ISOR
I don’t like places where hot stuff bubbles out of the ground, but Icelanders have no such issues. They’re now almost ready to start a new experiment that will drill right into a magma chamber. How do they know that this will not accidentally create a volcano? Let’s have a look.
Iceland is an island in the Northern Atlantic Ocean that sits right atop the Mid Atlantic Ridge. That’s where the North American and Eurasian tectonic plates rub. Those two plates are moving away from each other at a pace of approximately 2 centimetres per year. As the plates move apart, hot, molten rock – called magma -- can rise to the top. This is why Iceland sees frequent volcano eruptions and on occasion gets a new island, like this one which was born in 1963.
Not so surprisingly, Iceland has the largest per capita production of geothermal energy, which covers an amazing 66 % of the country’s primary energy needs.
Their most ambitious plan was the Iceland Deep Drilling Project. In their first attempt, in 2009, they tried to drill to a depth of 4 point 5 kilometres near Reykjavik, well above where they thought a magma reservoir was. However, just beyond 2 kilometres they drilled into an unexpected upper part of the magma chamber. The magma plugged the lowest 20 metres of the hole and damaged the drill. Aggressive gases began bubbling up that also damaged the surface equipment. Eventually the main valve failed, and the well was shut down.
They drilled a second hole in 2014 and encountered the same problem: The drill tapped onto a magma chamber where they didn’t expect it, and acidic gases wrecked the equipment.
You may wonder why they go to these troubles. The reason is, as so often, physics.
You see, usually geothermal power plants work by piping water through hot layers underground. This heats up the water, which creates pressure which can then be used to drive a turbine and create electricity.
But water has a limited capacity for how much energy it can transport, called the “enthalpy”. And the enthalpy of water makes a sudden jump at about 374 degrees Celsius. I understand that very well because at that temperature I would also jump. If it gets even hotter the water is neither a liquid nor a gas but both. The phase is called “supercritical”.
The amazing thing is now that supercritical water can carry several times more energy per mass, and the conversion to electric energy becomes more efficient. This means if you can build a geothermal plant with a reservoir hot enough so that the water becomes supercritical, that’ll suddenly dramatically increase the power production, by some estimates up to a factor 10. Supercritical water is kind of the holy grail of geothermal energy.
You might think that hitting upon magma and wrecking their equipment would have discouraged them, but not so. Yes, they had these nasty gasses and their drill got stuck in the magma, but it’s not like they accidentally created a volcano. Basically they concluded it wasn’t as bad as they thought it’d be.
So they’re doing it again, but this time on purpose. It’s called the Krafla Magma Testbed. They want to drill two new holes each about 2 kilometres deep, first nearby and then into the magma chamber that they know to be there.
The drilling for the first borehole is supposed to start by 2026. It will not drill right into the magma, but just close to the chamber to measure temperature and pressure. They also want to bring up samples from down there. The second new borehole will then actually drill into the magma chamber to test the possibility for a supercritical geothermal power plant.
Isn’t this kind of dangerous? Yes, it is. But. They know from the earlier drilling that while the magma chamber is under pressure, the pressure isn’t high enough to accidentally create a volcano. At least not unless the conditions down there have dramatically changed in the past 10 years. Honestly, I wouldn’t go anywhere near the thing.
The project has both scientific and technological purposes. They want to study the magma and what it’s doing under the earth when it’s not bubbling to the surface. According to the project’s website the purpose of this endeavour is an “Exploration into the utilization of super-hot, magma, geothermal energy and fluids” that “will revolutionize our energy landscape.”
According to the website New Civil Engineer, the project management’s now seeking funding of 79 million pounds for the first stage, so if you have a few million to spare, maybe they’ll send you a fresh magma sample in return.
Geothermal energy is a rather obvious source of energy. The energy that’s contained in the deeper layers of Earth is staggering. Geoscientists have estimate that the total energy reserves in the upper 10 kilometres of Earth’s crust would be enough to power the entire world population for several hundred million years.
That sounds amazing, but the problem is that in most places finding hot spots underground is quite difficult. And drilling into them is both difficult and expensive, really expensive. It’s also not irrelevant to note that it isn’t so uncommon that the gases which are released from underground during the operation of a power plant contain carbon dioxide.
On average, carbon dioxide emissions are low for the currently existing power plants. Though there are some examples in Turkey where geothermal plants actually emit more Carbon Dioxide than a typical gas power plant. However, how much they would emit with deeper drilling or new extraction techniques, nobody knows.
What all of this means is that geothermal energy is a good solution, in some places, and we can almost certainly get more out of it than we presently do. But in most places it’s difficult and expensive and is extremely unlikely to ever become our global main energy supply. And I for one am grateful for it. Because I don’t like hot stuff bubbling out of the ground…
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