Ar-Rehman

Rare isotope helium-3 is the 'Fuel of the future', usually found on the Moon

Helium-3 is usually talked about as a Moon resource, something future astronauts might mine from lunar dust to power fusion reactors or cool quantum machines. The forests and wetlands in northern Minnesota stored helium-3, a fuel expected to be found as a resource on the Moon’s surface. Drilling beneath the Topaz Project site near Babbitt, scientists confirmed the presence of helium-3. A concentration of 14.5 parts/billion was found in the lab tests, which was similar to what was measured in Apollo samples. The discovery could be a game-changer for the future of clean energy and was led by exploration company Pulsar Helium. Geochemist Dr. Peter Barry at the Woods Hole Oceanographic Institution conducted gas analyses, which revealed the site in Minnesota to be one of the most unexpected helium-3 reservoirs ever found. Helium-3 was one of the rarest substances on Earth and was found at trace levels in the atmosphere.

At the Topaz Project near Babbitt, drilling has revealed measurable, usable amounts of helium-3 in gas trapped deep underground. Lab tests show concentrations similar to levels measured in Apollo samples brought back from the Moon. The gas analyses suggest Minnesota may host one of the most unexpected helium-3 reservoirs ever identified. Helium atoms occur in different forms called isotopes. These are atoms which have an identical number of protons but have different numbers of neutrons. They all count as helium, but some are heavier than others. The helium was freed from mineral grains by heat beneath the surface and old faults in the crust, which helped to travel upwards through the rock. Nitrogen-rich gas at the Topaz site functioned as a carrier fluid, which dissolved the helium and transported it without adding carbon-heavy hydrocarbons. The helium-rich mixture was prevented from leaking by the layers of tight rock which formed a barrier and also helped build up the concentration. Methods such as cryogenic distillation and adsorption columns were used by engineers to test the production of pure helium-3 gas streams.

Helium-3 (3He) has two protons and one neutron, whereas the far more common helium-4 (4He) has two protons and two neutrons. Most terrestrial 3He comes from the decay of tritium in nuclear weapons and reactors. This is supplemented by tiny amounts trapped in natural gas fields. In Earth’s atmosphere, 3He is present only at trace levels, which is many orders of magnitude lower than the gas in Minnesota’s new reservoir. This precious gas can command around nine million dollars/pound. This price makes it vastly more valuable than everyday helium, according to industry analysis. US agencies ration 3He for programs including neutron detectors and cryogenics, the science of working at low temperatures. Because Topaz helium does not depend on aging nuclear stockpiles, even modest 3He recoveries here could ease those long-term supply constraints. “We are thrilled to announce this remarkable helium-3 discovery,” said Thomas Abraham-James, President and CEO of Pulsar Helium. The Topaz helium did not depend on aging nuclear stockpiles, and even modest recoveries could aid long-term supply constraints. Labs in Ohio and Massachusetts analyzed the gas concentrations and ratios from the samples from the Jetstream 1. The ratio of normal helium and Topaz helium was constant across the gas with both contents in a single source. The ratios were measured with a specialized noble gas mass spectrometer, an instrument used to sort gas atoms by mass. The northern bedrock of the state was built from ancient, uranium-rich crust, which had been slowly generating helium for billions of years.

Scientists measure worldwide production of 3He in tens of thousands of liters each year. This is far below the expected demand from quantum computers and laboratories. Separating 3He from 4He in a gas stream is difficult because the two isotopes behave identically unless cooled to extremely low temperatures. Engineers test approaches such as cryogenic distillation and adsorption columns. However, until now, no company runs a plant which produces pure 3He from gas streams. Pulsar has invited universities and technology firms to treat Topaz as a test ground for separation methods which might unlock a 3He stream. The state’s northern bedrock is built from ancient, uranium-rich crust, which has been quietly generating helium for billions of years. Heat from below, and old faults in the crust, help free that helium from mineral grains, letting it migrate upward through the rock. At Topaz, nitrogen-rich gas acts as a carrier fluid, dissolving the helium and transporting it upward without adding carbon-heavy hydrocarbons. Overlying layers of tight rock form a barrier which prevents the helium-rich mixture from leaking and allows it to build up concentrations.

The decay of tritium in nuclear weapons and reactors created most terrestrial helium-3 and was supplemented by small amounts trapped in natural gas fields. The magnitude of the resource found in Minnesota’s new reservoir was much larger than what was seen in Earth’s atmosphere. The resource is 100,000 times the cost of common helium. The resource was rationed for programs, like neutron detectors and cryogenics working at low temperatures. Because 3He captures slow neutrons so efficiently, it underpins highly sensitive detectors which search for illicit nuclear material and monitor research reactors. In refrigeration systems, 3He mixes with 4He to reach extremely low temperatures. This is critical for quantum computing, a method which uses quantum physics to process information. Researchers explore 3He as a fuel for fusion, a reaction where light atomic nuclei combine and release energy. Helium-3 also cools specialized experiments in condensed matter physics and powers advanced imaging methods. These roles give the gas an influence far beyond its tiny volumes. Minnesota has never produced oil or natural gas commercially, so lawmakers are writing rules as companies prepare to tap the Topaz reservoir. Local residents and tribal governments are weighing questions about groundwater, wildlife and noise. They are also watching potential jobs and tax revenues gather momentum. Some community members worry that Minnesota lacks experience with gas wells. They insist that regulators must examine drilling, flaring and reclamation plans carefully before production. For Minnesota, supporters see Topaz as a way to supply helium without importing from politically sensitive regions. It will also generate significant revenue for counties.

Gas samples from the Jetstream 1 well were analyzed in laboratories in Ohio and Massachusetts. Both laboratories agreed on the gas concentrations and ratios found. Across gas with 4He contents between one and eleven percent, the ratio of 3He to 4He stayed constant, suggesting a single source. Scientists express this relationship as a 3He to 4He ratio of about 0.09 relative to air. This makes it significantly higher than in typical crustal gases. Those ratios were measured with a specialized noble gas mass spectrometer, an instrument which sorts gas atoms by mass. Startups planning to mine 3He from the Moon have signed contracts with firms making quantum computing refrigerators and with the Department of Energy. “They will need more helium-3 than is available on planet Earth,” said Gary Lai, chief technology officer of Interlune. For Pulsar, the next steps include drilling more wells and estimating recoverable helium. They also need to decide whether separation technology can support a profitable project. If helium from Minnesota can be produced at scale, this potential fuel of the future might come from forests instead of lunar soil. The state of Minnesota need to keep a lookout for potential jobs and tax revenues which may occur as a result of the reservoir. Communities demand regulators for the plans scheduled for the site before full fledge production starts.