Are our helium reserves coming to an end? | Science| In-depth reporting on science and technology | DW | 01.07.2016
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Are our helium reserves coming to an end?

Helium is a supposedly rare resource. Now, hopes are focused on newly discovered deposits in Tansania. Geologists remain optimistic - looks like we'll continue to be able to fill our balloons. A shortage isn't imminent.

Geologists of the University of Oxford and the Norwegian mining company Helium One have announced the discovery of considerable helium reserves in a volcanic rift area of Tanzania. The estimated volume of the noble gas may amount to as much as 1.5 billion cubic meters, which is equivalent to the worldwide annual consumption of seven years - in the best case scenario.

"This figure sounds high at first, but we need to differentiate between resources and reserves", geochemist Martin Blumenberg points out. He works for the German Federal Institute for Geosciences and Natural Resources (BGR). "We don't know if it is possible to extract the helium for economical use."

Dr. Martin Blumenberg Geochemiker an der BGR

Martin Blumenberg is not worried about helium scarcity

Helium One is confident, however, that the discovery of the helium field could considerably ease the pressure on the worldwide market for the non-flammable, not-toxic and light noble gas. So far, helium is exclusively a by-product of natural gas and oil extraction. The gas in its highest purity is the result of fractional distillation.

Is extraction economical?

If it turns out that extracting helium from volcanic rift areas like the one in Tanzania actually works, it could help keep helium prices down for the time to come.

"In any case, it is a new kind of discovery and certainly an interesting thought," geochemist Blumenberg says. "I can imagine that this resource could become relevant in the future."

For that to happen, the infrastructure for extraction, storage and distillation would need to be installed first, though. All of that already exists in the cases of conventional natural gas exploration facilities.

Deutschland Galerie Zeppelin CargoLifter

Helium is the perfect gas for Zeppelins, blimps and weather balloons. The alternative - hydrogen - is explosive.

Whether helium production at a natural gas facility is economically viable depends mainly on two factors: The amount of helium within the natural gas and the total amount of gas extracted at the respective place.

The U.S. is leading in helium production, because in Arizona there are natural gas deposits which include up to seven percent helium. But even in Qatar, helium can be produced economically, even though the natural gas there contains less than 0.1 percent of helium. What is essential for the success there is the huge overall amount of gas that Qatar extracts.

This also has to be taken into the account in the case of the newly discovered helium deposits in Tanzania. In the rift area there, the helium content of the extracted volcanic gas is around four percent. But unlike with natural gas, the remaining 96 percent of the gas can not be used economically.

Prof. Mario Trieloff, Geologe an der Universität Heidelberg

Professor Trieloff believes that the new discovery could boost the search for unknown deposits

Not an infinite resource

Even though helium is - after hydrogen - the second most common element in our universe, it is rather scarce on planet Earth.

"That's because Earth is a rocky planet and not a gas planet, like for example Jupiter," Mario Trieloff explains. He is a professor for geochemistry and cosmochemistry at the University of Heidelberg. "On Jupiter, the atmosphere is rich in helium and hydrogen."

That has to do with gravity. Earth is simply not heavy enough to be able to hold both elements as gas. While hydrogen is still there in abundance because it is caught in water as a compound with oxygen, helium slipped away. And this is still going on today, Trieloff points out.

Helium from the emergence of Earth

The helium that the researchers found in Tansania is very old.

"A small part of the helium is the isotope helium 3. This was already trapped in rocks at the time of the formation of Earth. The larger part - the isotope helium 4 - emerged by way of radioactive decay throughout the history of our planet," professor Trieloff says.

Now it's breaking free - probably triggered by the heat of the volcanic activity.

"In places where rock melts, where there are unusually high temperatures or an occasional pressure relief, the helium can emerge and rise to the surface," Trieloff explains.

Fresh helium from nuclear fission

Even now, fresh helium is being generated below the Earth's surface by way of radioactive decay processes.

"Uranium and thorium decay are producing alpha-particles and those particles are nothing else but helium nuclei," Trieloff says. "They consist of two neutrons, and when they recombine with electrons, we get the most common helium isotope helium 4."

Deutschland Hochtechnologie Kernfusionsforschungsanlage Wendelstein 7-X in Greifswald

Superconducting coils, like the one at the Wendelstein 7-X reactor, are cooled with hydrogen.

Even though the uranium reserves on Earth are not that huge, they provide a steady supply of helium 4. "Uranium 238 has a half-life of four and a half billion years. That's roughly the equivalent of the age of planet Earth," Trieloff says. "That means we had just twice as much uranium then as we have today."

We may be optimistic

It also means that the helium production inside the Earth for the next four and a half billion years will still remain half as strong as it used to be.

"This is sufficient and should not cause us any big problems," the geologist argues.

There is enough helium trapped inside the planet. The only question is how to extract it and get it to the surface.

"The most exciting about the new studies is that we can now systematically look for additional helium deposits and narrow down possible extraction places," Trieloff says.

This may give companies an impetus to look for helium in less conventional places and not just as an occasional by-product of oil and gas.

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