Iceland is going to lower a drill five kilometers to reach rock at 400 degrees and try to extract clean energy on a scale that a common well cannot achieve.

Written by Douglas Avila

Published on 30/05/2026 at 23:56

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Iceland, which already derives much of its energy from the earth’s own heat, has decided to go much deeper and will lower a drill to about five kilometers to reach rock at 400 degrees, hoping to extract from a single well an amount of clean energy that a common borehole could never achieve.

Few places in the world have such an intimate relationship with underground heat as Iceland. The island sits on one of the most volcanic spots on the planet and has been harnessing this heat for decades to heat homes and generate electricity. But what’s at stake now is a leap in scale, a project called IDDP-3 that aims to drill much deeper than any common geothermal well.

The target is ambitious, to reach rocks at about 400 degrees at a depth of four to five thousand meters. In this extreme range, water ceases to be simply hot water or steam and enters a state called supercritical, where it carries much more energy than the common steam used in traditional geothermal plants. It is this concentrated energy that makes the project so promising.

What is supercritical water

It’s worth understanding this phenomenon because that’s where the magic lies. When water is subjected to extremely high temperature and pressure, it reaches a state where it is neither liquid nor gas, it’s something intermediate, dense, and full of energy. Such a supercritical fluid, brought to the surface, can spin turbines with much greater efficiency. Scientists’ estimates are encouraging, a single supercritical well would yield much more than several conventional wells combined.

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Drilling near hell

The technical challenge is daunting. Drilling to rocks at 400 degrees means taking equipment close to the limit of what materials can withstand. The drill, casings, and sensors need to endure heat that destroys common tools, as well as enormous pressures and corrosive fluids rising from the depths. It’s like trying to drill on the edges of a volcanic boiler and still control what comes from there.

Iceland itself has already experienced a preview of this. In a previous attempt in 2017, a well reached nearly four thousand seven hundred meters and encountered fluid at over 420 degrees in supercritical conditions, proving that the concept works, although it is brutally difficult to tame. The IDDP-3 is the continuation of this quest, now with more experience and the ambition to turn the feat into something truly usable.

Icelandic geothermal field with steam and pipelines — In 2017, an Icelandic well already found fluid over 420 degrees, proving that the concept works.

Energy that doesn’t depend on the sun or wind

There is an advantage of geothermal energy that often goes unnoticed amid the enthusiasm for solar and wind. The Earth’s heat is always there, day and night, rain or shine, wind or no wind. While panels and turbines depend on the weather and fluctuate, a geothermal well delivers constant energy, all the time, making it a firm and reliable base for an electrical system. It is precisely this stability that other clean sources lack.

Iceland itself is living proof of this potential. The country generates practically all its electricity from renewable sources, combining underground heat with the power of its waters, and has become a kind of global laboratory for clean energy. Precisely because it has already gone so far with conventional geothermal energy, it makes sense that it is there that the next big step is attempted, that of deep supercritical drilling. It’s the kind of advancement that only a country with such intimacy with the Earth’s heat would have the courage and knowledge to attempt first, paving a path that the rest of the world watches with attention.

If deep drilling like IDDP-3 succeeds and proves viable on a large scale, it could pave the way for deep geothermal energy to be taken to other parts of the world, not just volcanic places like Iceland. The technology developed there could, in the future, help entire countries seek clean energy by going deep, towards the heat that exists under our feet anywhere on the planet.

Aerial view of a modern geothermal plant in Iceland — A supercritical well would yield much more than several conventional wells combined.

Seeking the fire down below

I imagine the audacity of lowering a drill towards a rock at four hundred degrees, deliberately seeking the heat that most drilling tries at all costs to avoid. It’s a fascinating inversion of logic, instead of fleeing from the underground fire, Iceland goes after it, precisely because it is in this extreme that the most valuable energy lies.

With drilling scheduled to start later this year, this is one of those projects that will test, in practice, how far humanity can go to extract clean energy from the bowels of the planet. If it works, Iceland will once again show the world that the future of energy may not only be up there, in the sun and wind, but also deep down, in the ancient heat of the Earth itself, waiting to be reached by those who have the courage to drill deep enough.

Would you bet on the deep Earth’s heat energy as one of the great clean sources of the future?

Iceland is going to lower a drill five kilometers to reach rock at 400 degrees and try to extract clean energy on a scale that a common well cannot achieve.