When most people think of helium, they think of party balloons and funny voices, but the gas has far more important applications in MRI machines, welding, manufacturing semiconductors, deep-sea diving and blimps. Unfortunately, it has a tendecy to just float off irretrievably into space, and with our current reserves dwindling, the world has been on the edge of a global shortage. Now, a research team has developed a new approach to finding fields of the gas underground, and with the first use of the technique they've discovered a massive reserve in East Africa.
Earth's main supply of helium comes from deep underground, as a result of radioactive decay. As it bubbles up to the planet's crust over the course of several hundred million years, it often ends up trapped in the same reserves as natural gas, which is where our commercial supplies are tapped from. In fact, until now sources of helium have only ever been found unintentionally, while drilling for oil or natural gas.
This new reserve was discovered in the Tanzanian East African Rift Valley, where the heat from volcanic activity was found to release helium from the ancient rocks it's embedded in, and allow it to pool in gas fields closer to the surface. The research was conducted by scientists from the Universities of Oxford and Durham, along with the Norwegian helium exploration company, Helium One.
"We sampled helium gas (and nitrogen) just bubbling out of the ground in the Tanzanian East African Rift valley," says Professor Chris Ballentine of Oxford University. "By combining our understanding of helium geochemistry with seismic images of gas trapping structures, independent experts have calculated a probable resource of 54 billion cubic feet (BCf) in just one part of the rift valley."
That's enough to fill more than 1.2 million MRI scanners, and more than twice the amount held in reserve by the world's largest supplier, the US Federal Helium Reserve, which has just 24.2 BCf left. The annual global consumption of helium averages 8 BCf, and supplies aren't being replenished fast enough to keep up.
"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 Ballentine.
The problem with the Tanzanian reserve is that the volcanoes that allow the helium to escape the ancient rocks could end up diluting the gas.
"If gas traps are located too close to a given volcano, they run the risk of helium being heavily diluted by volcanic gases such as carbon dioxide," says Durham University's Diveena Danabalan. "We are now working to identify the 'goldilocks-zone' between the ancient crust and the modern volcanoes where the balance between helium release and volcanic dilution is 'just right'."
Danabalan presented a study last year that suggested huge reservoirs of helium were yet to be found under parts of North America, and this week will present this new research at the Goldschmidt geochemistry conference in Yokohama, Japan.
Source: Oxford University
