Vast helium reserves have been discovered in Tanzania that scientists say will rescue the world from a critical shortage of the rare gas.
A Norway-based exploration company, working with Oxford and Durham universities, discovered as much as 54 billion cubic feet (1.53 billion cubic metres) of the gas in the Rift Valley – enough to fill 600,000 Olympic-size swimming pools. It is the first time helium has been discovered intentionally.
The gas is vital for a wide range of purposes including welding, MRI scanners and the Large Hadron Collider, but global stocks of the gas have dwindled to such a point that there has even been pressure for a ban on the use of the gas for party balloons.
“This is a game-changer for the future security of society’s helium needs and similar finds in the future may not be far away,” says Chris Ballentine of the University of Oxford.
The discovery vindicates a new exploration technique that is expected now to be applied to other parts of the world with similar geology – the western mountain regions of North America show potential, scientists say.
Global helium consumption is about 8 billion cubic feet per year and the US Federal Helium Reserve, which is the world’s largest supplier, has just 24.2 billion cubic feet.
Total known reserves in the US are about 153 billion cubic feet.
All helium in use is naturally occurring but it is usually only discovered accidentally in small quantities during oil and gas drilling.
Although it is the second most abundant element in the universe, it is relatively rare on Earth, making up about 0.0005% of the atmosphere. This is because, as a very light element, once it escapes into the air it floats off into space.
While hydrogen is lighter, it is common as it is captured in molecules of water or organic compounds, whereas helium is a so-called noble gas – it is inert and forms no compounds even with itself except under exceptional experimental conditions.
The colourless, odourless gas was first detected in the chromosphere of the sun in 1868, but was not discovered on Earth until 1895 when English chemist William Ramsay found signs of it in the spectra of gases released when treating a uranium-based mineral.
Most helium on Earth is helium-4 (4He), which is produced by radioactive decay of uranium- and thorium-rich minerals deep below the surface.
As these heavy elements decay, various forms of particles are emitted including alpha particles – effectively a helium nucleus of two protons and two neutrons.
By picking up two electrons it forms the helium atom, which percolates up through the crust in a process that takes millions of years. It is then released during periods of tectonic activity and it was this that tipped off the researchers to its presence in Tanzania. Volcanic activity in the Rift Valley releases helium buried in ancient rocks, which rises up and becomes trapped in shallower gas fields.
The United States is the largest producer of helium in the world and exports more than 2.5 billion cubic feet, according to United States Geological Survey statistics.
Uses of helium
- In space to keep satellite instruments cool.
- To clean out rocket engines.
- It was used to cool the liquid oxygen and hydrogen that powered the Apollo spacecraft.
- To pressurise the fuel tanks of liquid fueled rockets.
- As an inert shield for arc welding.
- 80% helium is combined with 20% oxygen to create a nitrogen-free mix for deep sea divers to prevent nitrogen narcosis.
- Liquid helium is a cryogenic material used to study superconductivity.
- To create superconductive magnets as used in medical MRI scanners.
- It is used as a cooling medium for the Large Hadron Collider.
- Helium-neon gas lasers are used to scan barcodes at supermarket checkouts.
- Helium gas is used to inflate blimps, scientific balloons and party balloons.
Bill Condie is a science journalist based in Adelaide, Australia.
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