The Untapped Carbon-Neutral Energy Source That Can Power Humanity Twice Over

Deep sea geothermal could be an utter game-changer.

By now, you probably heard that we need a tonne of on-tap green energy to save the planet. You may also know that many of our current solutions are far from perfect. Nuclear power is too expensive, takes far too long to build, and still has a bit of a waste problem. Solar and wind are unpredictable and require a complete redesign of our energy grinds and the installation of giant grid batteries to function as a sole energy source; they can also drive vast amounts of habitat loss. Geothermal power doesn’t suffer from any of these issues and has just as tiny a carbon footprint, but it’s only viable in a few locations on Earth. So, how do we solve this conundrum? Well, a new form of geothermal energy is gaining traction that promises to be the ultimate clean energy technology. But is it?

Before we dive in, let’s quickly recap what geothermal energy is. In locations of geological activity, the heat of the Earth’s mantle comes so close to the surface that we can access it with deep wells. The temperature of the rocks at the bottom of these wells is enough to flash heat water into steam. So, to extract energy from these wells, we pump water down them, and the high-pressure steam that thrusts back to the surface is siphoned off and used to spin a turbine, creating electricity. This steam is then collected, cooled, condensed, and sent back into the well. This is how most geothermal power plants work, with some variations driven by the well temperature and the nature of the rock bed.

The issue is, on land, there are very few places where the mantel’s heat comes close enough to the surface for us to access it. But the same isn’t true out to sea. Out there, the Earth’s crust is naturally thinner. In locations of “seafloor spreading”, where a boundary between two tectonic plates is actively creating new crust, such as the mid-Atlantic ridge and the Pacific Ring of Fire, this heat is just below the surface (geologically speaking). This means there is far more geothermal energy available out to sea than there is inland. In fact, researchers have estimated that the total global offshore geothermal energy potential is 72,000 TWh per year! That is 2.88 times more energy than humanity currently consumes each year.

Scientists and engineers have known about this for years. However, many assumed the cost of building oil-rig-like offshore geothermal plants would render them useless.

But a recent white paper from CGG suggests that isn’t the case. They found that they might actually be cheaper than land-based geothermal power plants! CGG did a survey and found this seafloor spreading geothermal locations are much more reliable, have much more consistent temperatures and are much closer to the surface than geothermal locations on land. This, in turn, increases the success rate of setting up a geothermal well, makes operation and maintenance far easier, and can extend the life of the well, which all work together to bring the cost way down to viable levels.

So, will this revelation kick-start an offshore geothermal revolution?

Probably not just yet. No one has developed the infrastructure needed to pull this off, let alone tested it or scaled up the industry and associated infrastructure required to enable them. Moreover, these seafloor-spreading locations are literally hundreds, if not thousands, of miles away from any human civilisation. We do have the technology to efficiently transmit electricity over such a distance, but again, it is far from commonplace. It will take considerable effort to bring this energy source to fruition, and it could take decades to scale. But surely, such an effort is worth it to unlock enough cheap, bountiful, on-tap carbon-neutral energy to power the world many times over?

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(Originally published on PlanetEarthAndBeyond.co)

Sources: CGG, New Atlas, Think Geoenergy, Utilities 1, Statista, EPA