The war in Iran, and the subsequent closure of the Strait of Hormuz, has unfortunately made us all familiar with details of the petroleum supply chain that we could formerly happily ignore. Every day we get some new story about some good or service that depends on Middle East petroleum and the production of which has been disrupted by the war. Fertilizer production, plastics, aluminum, the list goes on.
One such supply chain that’s suddenly getting a lot of attention is helium. Helium is produced as a byproduct of natural gas extraction: it collects in the same underground pockets that natural gas collects in. Qatar is responsible for roughly 1/3rd of the world’s supply of helium, which was formerly transported through the Strait of Hormuz in specialized containers. Thanks to the closure of the strait, helium prices have spiked, suppliers are declaring force majeure, and businesses are scrambling to deal with looming shortages. (For many years the US government maintained a strategic helium reserve, but this was sold off in 2024.)
What I find interesting about helium is that in many cases, it’s very hard to substitute for. Helium has a unique set of properties — in particular, it has a lower melting point and boiling point than any other element — and technologies and processes that rely on those properties can’t easily switch to some other material.
Helium is the second lightest element in the periodic table (after hydrogen), and the second most common element in the universe (also after hydrogen). But while helium is very common on a cosmic scale, here on earth it’s not so easy to get. Because helium is so light, it rises to the very top of the atmosphere, where it eventually escapes into space. So essentially all helium used by modern civilization comes from underground.
Helium is produced via the radioactive decay of elements like uranium and thorium, and it collects in underground pockets of natural gas. This source of helium was first discovered in the US in 1903, when a natural gas well in Kansas produced a geyser of gas that refused to burn. Scientists at the University of Kansas eventually determined that this was due to the presence of helium. Like petroleum, helium has collected in these pockets over the course of millions of years, and thus (like petroleum) there’s a limited supply of underground helium that can be extracted. As with petroleum, people are often worried that we’re running out of it.
Because helium is a byproduct of natural gas extraction, and because only some natural gas fields have helium in appreciable quantities, a small number of countries are responsible for the world’s supply of helium. The US and Qatar together produce around 2/3rds of the world’s helium supply. Russia, Algeria, Canada, China, and Poland produce most of the remaining balance.
Elemental helium has a few different useful properties. The most important one is that, thanks to the small size and completely filled outer electron shell of helium atoms, helium has a lower boiling point than any other element. Liquid helium boils at just 4.2 kelvin (-452 degrees Fahrenheit). By comparison, liquid hydrogen boils at 20 K, and liquid nitrogen boils at a positively balmy 77 K.
Its low boiling point makes helium very useful for getting something really, really cold. When a liquid boils, it transforms into a gas, and during this process it will pull energy from its surroundings due to evaporative cooling. This is why your body sweats: to cool you down as the liquid evaporates. When a liquid has a very low boiling point, this heat extraction happens at a very low temperature. Helium also stays a liquid at much lower temperatures than other elements. Nitrogen freezes solid at 63 K, and hydrogen freezes at 14K, but at atmospheric pressure helium stays a liquid all the way to absolute zero. If you need to cool something to just a few degrees above absolute zero, liquid helium is essentially the only practical way to do that.
Helium also has a few other useful properties. As we noted, helium is very light: it will naturally rise in the atmosphere, which makes it useful as a lifting gas. Thanks to its filled outer electron shell, it is inert, and won’t react with other materials. Helium also has high thermal conductivity — at room temperature, helium can move heat about six times better than air.
The world uses around 180 million cubic meters of helium each year. (This sounds like a lot, but it’s just 0.11% of the 159 billion cubic meters of nitrogen the world uses each year, and 0.004% of the over 4 trillion cubic meters of natural gas that the world uses each year.) But while it’s not used in enormous quantities compared to some other gases, helium is nevertheless quite important. Different industries make use of helium’s properties in different ways, and while in some cases there are reasonable substitutes for helium, in most cases helium has no practical replacement.
MRI machines
Some of the biggest consumers of helium are MRI machine operators, which consume around 17% of the helium used in the US. MRI machines work by creating very strong magnetic fields, which change the orientation of hydrogen atoms in tissues in your body. A pulse of radio waves is then sent into your body, which temporarily disrupts this orientation. When the pulse stops, different types of tissue return to their alignment with the magnetic field at different rates, and that rate of change can be measured and converted into a picture of the interior of the body. The strong magnetic fields in MRI machines are created by superconducting magnets: when some materials get cold enough, they drop to zero electrical resistance, which makes it possible to put enormous amounts of electrical current through them and create extremely strong magnetic fields. The vast majority of MRI machines used today use superconducting magnets made from niobium-titanium (NbTi), which becomes superconducting at 9.2 degrees above absolute zero. This is well below the boiling point of any other coolant, making liquid helium the only practical option for cooling the magnets. A handful of MRI machines have been built using higher-temperature superconductors that don’t require helium cooling, but the vast majority of the 50,000 existing MRI machines in the world require helium.
The helium consumption of MRI machines has fallen drastically over time. Early MRI machines would lose helium at a rate of around 0.4 liters per hour, requiring large tanks of 1000-2000 liters that needed to be refilled every few months. (It’s notoriously difficult to prevent gaseous helium from leaking out of containers, which is why helium is also often used for leak detection.) But modern MRI machines are “zero boil-off,” which essentially never need to be recharged with helium. As these machines take up more market share, the helium requirements of MRI machines can be expected to fall. But for the foreseeable future, MRI will remain a substantial source of demand.
Semiconductors
Another major consumer of helium is the semiconductor industry, which uses around 25% of the helium worldwide, and around 10% of the helium in the US. As with MRI machines, helium is used to cool superconducting magnets, which are used to increase the purity of silicon ingots grown using the Czochralski method. Helium is also used as a coolant in some production processes, as well as a non-reactive gas to flush out some containers, for leak detection, and for a variety of other uses. A 2023 report from the Semiconductor Industry Association noted that helium was used “as a carrier gas, in energy and heat transfer with speed and precision, in reaction mediation, for back side and load lock cooling, in photolithography, in vacuum chambers, and for cleaning.” The same report notes that for many of these uses, helium has no substitute.
Unlike MRI machines, which have used less and less helium over time, helium usage in the semiconductor industry seems to be trending up: some sources claim that helium consumed by the semiconductor industry is expected to rise by a factor of five by 2035. This seems to be in part due to the development of DUV and EUV semiconductor lithography machines, which require helium to function. Unlike many other gases, helium absorbs almost no EUV radiation, which (as I understand it) makes it hard to substitute for helium in EUV machines.
Fiber optics
Helium is also used in the manufacturing of fiber optic cable. Optical cable is made with an inner core of glass, surrounded by an outer “sleeve” of glass with a different index of refraction. This keeps photons within the inner core via the phenomenon of total internal reflection. During the manufacturing process, helium is used as a coolant when the outer “sleeve” is being deposited onto the core — with any other atmosphere, bubbles form between the two layers of glass. Roughly 5-6% of helium worldwide is used for the production of optical fiber, and there’s no known alternative.
Purging gas
Other than semiconductor manufacturing, other industries (particularly the aerospace industry) use helium as a “purge gas” to clean out containers. Cleaning out a tank of liquid hydrogen, often used as a liquid rocket fuel, requires a gas with a boiling point low enough that it won’t freeze when it contacts the hydrogen. Cleaning a tank of liquid oxygen doesn’t require a gas with quite as low a boiling point, but it is best to use an inert gas to reduce the chance of it reacting with the highly reactive oxygen. Aerospace purging makes up around 7% of US helium consumption. Around half of that is used by NASA, which is the single biggest user of helium in the US.
Lifting gas
Because helium is lighter than air, it’s also used as a lifting gas in balloons and lighter-than-air airships as an alternative to the highly flammable hydrogen. Each Goodyear Blimp, for instance, uses around 300,000 cubic feet of helium. Around 18% of the helium consumed in the US is as a lifting gas.
Scientific research and instruments
Helium is also widely used in scientific research. Much of this is for keeping things cold: superconducting magnets, such as those used in the Large Hadron Collider, typically require helium, as do the superconducting elements in SQUIDs, which are highly sensitive magnetic field detectors. Helium is also used in mass spectrometers, which are used for, among other things, detecting microscopic leaks in containers.
This is a major category of use in the US; roughly 22% of its helium consumption goes to “analytical, engineering, lab, science, and specialty gases.”
Welding
In the US, helium is also used for welding: its high thermal conductivity and its inertness make helium an excellent shielding gas, which prevents the pool of molten metal from being contaminated before it cools. In the US, welding makes up roughly 8% of helium use, but elsewhere in the world, it’s more common to use other shielding gases like argon.
Diving
Helium is also used for breathing gas in deep sea commercial diving. At depths beyond 30 meters, breathing nitrogen (which makes up 78% of normal air) causes nitrogen narcosis, and diving beyond this depth is done using gas mixes that replace part of the nitrogen for helium. Roughly 5% of helium consumed in the US goes towards diving.
Helium for diving is difficult to substitute for. Virtually every other breathable gas except for possibly neon causes some degree of narcosis, and neon is heavier than helium, making breathing more difficult.
For some of these applications, it’s possible to substitute helium with other materials. There are other shielding gases, such as argon, that can be used for welding, and other lifting gases, such as hydrogen, that can be used for balloons or airships. In other applications, it’s possible to dramatically reduce the consumption of helium via recycling systems or other methods designed to reduce its use. As we’ve noted, this has occurred with MRI machines, where modern ones use far less helium than their predecessors. And it seems to have happened with aerospace purging. A 2010 report from the National Academies of Sciences notes that if NASA and the Department of Defense were sufficiently motivated, they could dramatically reduce their helium consumption by recycling it. Since then, aerospace use of helium has fallen from 18.2 million cubic meters (26% of total US consumption) to 4 million cubic meters (7% of total US consumption). But the United States Geological Survey notes that most helium in the US is still unrecycled, and there’s lots of opportunity to dramatically reduce helium usage with various recapture and recycling systems. Many of these systems are capable of reducing helium consumption by 90% or more.
But “reducing” doesn’t mean “eliminating,” and it’s interesting to me how in so many cases there doesn’t seem to be any good substitute for helium.