Lift-off in hunt for hidden helium? Durham researchers help develop new model

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Durham researchers have helped to develop a new model that could be used to identify new helium gas resources – especially important in light of the global helium supply shortage. The study, published in Nature, was led by the University of Oxford, with Durham’s involvement led by Professor Jon Gluyas, Executive Director of the Durham Energy Institute.

The proposed model helps to explain the existence of previously unexplained sources of helium. In doing so, the study also identifies the geological locations where helium is likely to be found, so it can be tapped and extracted without emitting greenhouse gases.

Helium may be the second most abundant element in the Universe, but it’s quite rare down on Earth. While helium is constantly being produced by radioactive decay in the Earth’s crust, it is also constantly escaping – and not just in the form of runaway party balloons. Helium is light enough that it can get enough heat at the top of the atmosphere that it can simply float away and escape the Earth’s gravity.

Helium’s constant escapology means it is currently a finite resource

Sometimes helium ions produced by radioactive decay – alpha decay, a common form of radioactive decay, produces alpha particles which are just helium atoms without the electrons – fire energetically into the atmosphere. While they would usually be deflected by the Earth’s magnetic field due to their charge, they can sometimes collide powerfully enough with molecules in the atmosphere to steal their electrons, leaving the helium neutral and free to escape into space.

Helium atoms are tiny, so great at diffusing – just think of a party balloon a few days after your birthday. Helium usually escapes the Earth’s crust by diffusing through water all the way until it reaches Earth’s surface.

However, the new study considered the effect of nitrogen on this typical helium-escape narrative. The research identifies the geological parameters required for nitrogen concentrations to be high enough to form gas bubbles. If nitrogen bubbles are present the helium will escape from the water into the gas and bubble towards the surface.

If these helium-rich bubbles hit a low permeability rock that they can’t pass through then they will become trapped. If the overhanging rock has the right structure, this could result in a substantial helium-rich gas field.

The most pessimistic predictions have helium running out within the next 20 years

Helium’s constant escapology means it is currently a finite resource. Today, most helium is produced as a by-product of natural gas production by fractionally distilling the extracted gas mixture. As the mixture is cooled other gases (like nitrogen and methane) liquify, while helium, which has a lower boiling point than any other element, remains gaseous.

The most pessimistic predictions have helium running out within the next 20 years. While this seems unlikely, massive supply shortages have already become common, with at least four such events since 2006 (including last summer).

Should we be worried about helium running out? Yes. Helium isn’t just used for balloons and high-pitched voices; it is vitally important to cool the superconducting magnets used in MRI scanners. It is also used in the manufacture of computer chips, scientific research, quantum computing, and more.

The radioactive processes that produce helium can also split apart water molecules to form hydrogen in a process called radiolysis. Hence, the proposed model also predicts the co-occurrence of hydrogen resources. Much of the hydrogen produced will have escaped or been consumed by microbes, but much may still remain.

Hydrogen burns with oxygen to produce only water, so has immense potential in helping the world transition to net zero (and beyond). However, more than 99% of hydrogen is currently produced from coal and methane, which itself accounts for over 2% of global CO2 emissions.

If the new model is found the be effective at predicting locations of economically viable hydrogen and helium resources, it could be vitally important in solving the global helium shortage and potentially helping the world to transition to cleaner fuels.

Image: Generated with OpenAI’s DALL-E 2

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