Helium is a noble gas renowned for its unique properties, including being the second-lightest element and possessing the lowest boiling point of any substance. This extremely low boiling point, near absolute zero, makes it indispensable for applications like cooling superconducting magnets in MRI machines and specialized welding. Unlike most resources, helium is non-renewable on a human timescale. Because it is so light, once it escapes into the atmosphere, Earth’s gravity cannot hold it, allowing it to eventually leak into space. Obtaining this high-value element is complex, requiring it to be captured before it escapes and isolated from other gases.
Geological Formation and Accumulation
The helium gas captured deep beneath the Earth’s surface has a distinct geological origin, separate from the formation of natural gas. Nearly all the helium collected on Earth, specifically the isotope helium-4, is created through the slow process of radioactive alpha decay. Heavy elements like uranium-238, uranium-235, and thorium-232, naturally present in the Earth’s crust and mantle, decay over billions of years.
During this decay, these radioactive elements emit an alpha particle, which is essentially a helium nucleus. Once the alpha particle slows down, it collects electrons from the surrounding rock to become a neutral helium atom. This generated helium then begins a slow migration, diffusing out of the mineral grains where it was created and into the surrounding groundwater and rock pores.
For helium to be concentrated into a commercially recoverable reservoir, it must interact with a carrier gas, typically natural gas or nitrogen, which helps extract the dissolved helium from the groundwater. The mixture then migrates upward through faults and porous rock formations. It eventually becomes trapped beneath a dense, impermeable layer of rock, known as a caprock, that prevents its escape. Because the helium molecule is extremely small, the integrity of this geological seal must be exceptionally high to prevent the gas from diffusing away.
Cryogenic Separation and Purification
The industrial process focuses on extracting usable helium from the raw natural gas mixture where it has accumulated, which is the only current commercial source. Because helium is a chemically inert noble gas, it cannot be separated using chemical reactions. Instead, processing relies on the dramatic differences in the boiling points of the constituent gases, a technique called cryogenic separation.
The raw gas mixture must first undergo pretreatment to remove contaminants like water vapor, hydrogen sulfide, and carbon dioxide. This step is necessary because these substances would freeze and create blockages at the extremely low temperatures required for separation. Once pre-treated, the gas stream is cooled in stages to progressively lower temperatures.
The mixture is typically cooled to around -150°C, causing the majority of methane and heavier hydrocarbons to condense into a liquid state. This leaves behind a gaseous mixture primarily composed of nitrogen and helium, often referred to as crude helium. The crude helium is then cooled further to separate the nitrogen, which liquefies at approximately -196°C. Helium remains a gas because its boiling point is -269°C.
This fractional distillation process separates the crude helium stream from the liquid nitrogen, yielding a gas that is typically between 50% and 90% helium. To achieve the ultra-high purity required for industrial and scientific applications, such as 99.999% purity, the stream undergoes a final purification step. This final stage often involves using pressure swing adsorption (PSA) or further cryogenic steps to remove the last traces of nitrogen, hydrogen, and contaminants.
Major Global Reserves and Infrastructure
The occurrence of natural gas fields with high concentrations of helium is geographically rare, localizing the supply to specific regions globally. For a field to be economically viable for helium extraction, the concentration must generally be above 0.3% by volume. Global production is heavily concentrated in a few countries, with the United States, Qatar, Algeria, and Russia holding the largest known reserves.
Historically, the United States has been the world’s leading producer, largely due to the massive Hugoton-Panhandle field across Texas, Oklahoma, and Kansas. The US Federal Helium Reserve, located near Amarillo, Texas, played a major role in global supply for decades, though its production share has recently declined. Today, nations like Qatar, drawing from its enormous North Dome natural gas field, have become major suppliers.
The infrastructure for managing helium is unique because of its extremely low liquefaction temperature. Once purified, the gas is often liquefied for storage and transport, requiring specialized, heavily insulated containers and pipelines. Helium is stored and moved as liquid at -269°C to significantly reduce its volume, which is necessary for efficient distribution worldwide. This specialized transport network highlights the logistical challenges in bringing the gas from its deep underground source to the global market.