How is Helium Gas Obtained?
Helium – the colorless, odorless and tasteless inert gas – is the second most abundant gas in the universe after hydrogen gas. However, the type of helium gas used in applications, such as gas chromatography, is extracted from natural gas – a problem of diminishing resources which is leading to the scarcity of helium gas.
Helium gas is plentiful in space – it is a by-product of fusion reactions occurring inside stars. However, the helium gas we can find on earth, which is then stored in helium gas tanks for usage in many critical applications, is limited. This type of helium gas, referred to as helum-4, is produced naturally underground through the radioactive decomposition and decay of certain elements such as uranium and thorium. The result of this reaction are alpha-particles containing two neutrons and protons. These small fragments then collect electrons from their surroundings and form helium, which later makes its way up through the crust of the earth and all the way up to space.
Luckily for us, some of helium-4 gets entrapped and mixes with the natural gas found under layers beneath the earth’s surface. Helium-4 is then extracted from the ground with wells drilled to release it. The amount of helium gas that can be found in the natural gas varies from almost negligible to 4% by its volume. The natural gas containing helium-4 then undergoes a process of cryogenic distillation to obtain the helium particles. Once separated from natural gas, helium-4 goes through another process of refining after which it is brought to 99.99+% purity for market sale.
Helium gas reserves and supply-chain
The global demand for helium continues to increase, causing major concern over the finite resource of helium gas, thereby rendering the supply chain fragile. The problem with extracting helium gas is that not many natural gas fields have high concentrations of helium gas and extracting helium from such fields would be too costly for the meagre levels of gas obtained. According to Gas World, 75% of global helium consumed globally is largely limited to three locations: Ras Laffan Industrial City in Qatar, ExxonMobil in Wyoming and the National Helium Reserve in Texas.
As another option for sourcing helium amid scares over its scarcity, some researchers have suggested producing helium through liquified air but the expense behind the production for the helium produced wouldn’t be feasible, as the amount of helium contained in air is too low.
Helium gas alternatives for Gas Chromatography
So why is helium so valuable? It’s all down to the very unique characteristics of helium gas that make the gas so precious to a variety of applications across industries. However, because of the uncertainty on the future supply of helium gas and the inevitable inflation of the costs involved, many industries are resorting to other sources for their applications.
Gas chromatography is one of such applications utilising other gases as a carrier gas instead of helium. Although the choice of carrier gas depends on the contents of the sample, hydrogen gas is one of the main contenders as a substitute for helium. Having very low viscosity, hydrogen gas can provide the highest mobility rate of all carrier gases, reducing time for sample analysis.