Helium (He) is a colorless, odorless, and non-reactive noble gas, the second-lightest element in existence. Its unique properties, especially its extremely low boiling point—the lowest of any element—make it an irreplaceable substance in modern technology. It is used extensively in cryogenics to cool the superconducting magnets in Magnetic Resonance Imaging (MRI) machines, accounting for a significant portion of global use. It also serves to purge and pressurize fuel tanks in rocketry and is employed in the manufacturing of semiconductors and fiber optics. Since this limited resource is not manufactured by humans, its natural origin and commercial acquisition are important questions.
How Helium Forms Deep Within the Earth
The terrestrial supply of helium is generated continuously within the Earth’s crust and mantle through alpha decay. This process involves the natural radioactive breakdown of heavy elements, primarily uranium-238, uranium-235, and thorium-232, found within rock formations. When these unstable elements decay, they emit an alpha particle—the nucleus of a helium-4 atom, consisting of two protons and two neutrons.
Once released, the alpha particle rapidly collects two free electrons from the surrounding environment to become a neutral, gaseous helium atom. Over geologic time, the continuous decay of these trace radioactive elements has produced nearly all the helium found on Earth. The resulting gas then migrates upward through faults and fissures in the rock.
The gas accumulates and becomes trapped beneath impermeable layers of rock, often combining with other gases in subsurface reservoirs. This geological entrapment makes helium available for extraction, as untrapped helium would eventually escape the Earth’s atmosphere due to its lightness.
Extracting and Processing Commercial Helium
Commercial helium is not found in dedicated “helium fields” but is recovered as a byproduct during the extraction and processing of natural gas. For extraction to be economically viable, the natural gas reservoir must contain a helium concentration greater than 0.3% by volume. These helium-rich deposits are geographically scarce, with the largest known reserves concentrated primarily in the United States, Qatar, and Algeria.
The recovery process begins with the raw natural gas stream, which contains methane, nitrogen, and crude helium. Separation is achieved using cryogenic distillation, an industrial technique that exploits helium’s extremely low boiling point. The gas mixture is progressively cooled to temperatures near the liquefaction point of methane and nitrogen.
At temperatures around -193°C, components like nitrogen and methane condense into liquids and are drained away. Because helium has the lowest boiling point of any element, it remains gaseous and is separated from the liquefied impurities. This initial process yields crude helium, which is 50% to 70% pure.
The crude helium is further refined through additional cooling and purification steps, often involving pressure swing adsorption (PSA). This achieves the high purities—often 99.999% or higher—required for advanced applications like medical scanners and electronics manufacturing. The reliance on the natural gas supply chain and the costly, energy-intensive cryogenic process makes the commercial supply vulnerable to shortages and price fluctuations.
Helium’s Cosmic Origins
While terrestrial helium is a product of radioactive decay, the vast majority of helium in the universe originated cosmically. Helium is the second-most abundant element in the cosmos, making up nearly 24% of the total elemental mass. Most of this primordial helium was created moments after the Big Bang, during Big Bang nucleosynthesis.
In the first few minutes of the universe’s existence, the incredibly hot, dense plasma cooled, causing protons and neutrons to fuse and create the nuclei of light elements, including hydrogen, deuterium, and helium-4. Since that initial formation, stars like our Sun have continuously generated new helium through nuclear fusion. Within a star’s core, hydrogen atoms are fused in a reaction known as the proton-proton chain to form helium, releasing enormous energy. This cosmic supply remains inaccessible and irrelevant to Earth’s commercial needs, emphasizing the finite nature of the usable helium trapped underground.