How much energy we use and where it comes from has long been the central problem of the climate crisis. That’s why some strategies have turned to tapping into new, cleaner fuels. A new discovery of a vast reserve of hydrogen energy hiding under the Earth’s surface could help – but just how much of a difference could it make?
Geologic hydrogen is formed during natural geochemical processes in the Earth and, so far, has been discovered in just a few places, including Albania and Mali. A new study, published in journal Science Advances, estimates these reserves stretch all around the globe.
The study’s authors suggest that if we were able to extract just 2 per cent of this geologic hydrogen, it could provide us with 1.4 × 1016 joules of energy. Sounds impressive, right? Actually, that’s only equivalent to the world population’s energy consumption for 35 minutes.
Still, that’s actually twice as much energy that’s in all the natural gas reserves on Earth, and the researchers say it could help policymakers meet net-zero carbon targets. After all, the current main ways of getting hydrogen are from fossil fuels or via a process known as electrolysis, which uses a lot of water and often has a high carbon footprint.
Extracting geologic hydrogen is a comparatively low-carbon process – though currently Mali is the only place where this is being done.
For the new study, the researchers from the US Geological Survey built a model to estimate the size of these reservoirs globally, combining prior understanding of how hydrogen occurs and behaves with geologic data.
This model suggests there may be as much as 5.6 × 106 metric tonnes (that’s the equivalent weight of 3.7 million cars, or 1.56 billion flamingos) of hydrogen hiding beneath the surface.
Experts are unsure, however, if we should dedicate resources to extracting this. “To suck up hydrogen at a scale required to make a contribution to bringing down emissions and tackling the climate emergency would require an enormous global initiative, for which we simply don't have time,” Prof Bill McGuire, Earth scientist at University College London (UCL) who was not involved in the study, told BBC Science Focus.
“It would also need a massive amount of supporting infrastructure in terms of rigs, access roads, storage, transport and more. Furthermore, it seems to me that we might now know how much hydrogen there is, but that is not the same as knowing where it is.
“There is more than enough free energy available from wind and the Sun alone, and the technologies are straightforward, well-tested and well-established, so I really don't see the need for exploiting what is, ultimately, another finite resource.”
About our expert
Prof Bill McGuire is a volcanologist, climate scientist, writer and broadcaster. He is currently Professor of Geophysical & Climate Hazards at UCL, and has written several books including Natural Hazards and Environmental Change; A Guide to the End of the World - Everything You Never Wanted to Know; Surviving Armageddon - Solutions for a Threatened Planet; Seven Years to Save the Planet; and his latest, Sky Seed.
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