Lancaster University's valuable helium-3 stash and lunar extraction plans

One of the most valuable assets owned by Lancaster University is stored in beer kegs. In a carefully locked laboratory, rows of metal kegs are arranged on shelves and linked together with spindly copper pipework. The containers aren't loaded with prize beer but rather a gas called helium-3, one of the most expensive materials in the world.

A single litre costs roughly $2,000 (£1,500), though the price can fluctuate. "The lab has been going for 50 years or so. Back then, the helium was quite cheap," says Dima Zmeev, senior lecturer.

"Our very wise predecessors stocked up." In the near future, more people could be looking to build up such a stockpile. Helium-3 has applications in quantum computing and nuclear fusion. However, the main source of it today is tightly controlled – it comes from nuclear weapons.

Specifically, from the decay of tritium, a form of hydrogen, inside those weapons. Around the world, tens of thousands of litres of helium-3 are likely to be produced this way every year, estimates David McCollum, distinguished scientist at Oak Ridge National Laboratory in Tennessee. But future demand could far exceed that supply.

Some entrepreneurs and researchers say we need new sources of helium-3. It exists in the ground, though generally at very low concentrations. However, samples of moon dust, or regolith, from the Apollo missions suggest it may be present there at relatively high concentrations.

As such, plans are now afoot to recover helium-3 from the moon. Helium-3 is an isotope of helium, defined by the number of neutrons in the atom's nucleus. Helium-4, with one additional neutron, is the comparatively cheap version – a gas that fills children's party balloons.

Zmeev uses helium-3 in physics experiments. For example, he fills tiny chambers with the stuff, in a project to detect a type of mysterious dark matter particle. Should such a particle knock into one of the helium-3 atoms, it would make them all jiggle.

This generates heat and that slight temperature rise can be measured. The helium-3 can be re-used again and again. Scientists mix helium-3 and helium-4 together at very low temperatures to create the lowest temperatures in the known universe, down to the millikelvin range (-273C).

When helium-3 atoms gradually separate from a dilute mixture containing the two isotopes, they form a pure helium-3 layer on top. This separation is a phase change that consumes energy, inducing a cooling effect , like when steam evaporates off a cup of hot water. Helium-3-based cooling, or dilution refrigeration, is crucial for quantum computers.

And helium-3 could also be used in some nuclear fusion reactors to one day create vast amounts of clean energy. One company planning to extract helium-3 from the moon is Interlune, based in Seattle. "We've spent the last four years developing, prototyping and testing technologies… We have a team of 30 people, and growing," says Rob Meyerson, co-founder and chief executive.