Sources of helium – Some uplifting news

When students are introduced to the periodic table, generally they already recognize a few elements. Even the least scientifically inclined students will have a few names pique their attention. Oxygen is surely an important example, and elements like uranium always seem to attract public attention. Among these popular elements, helium is undeniably near the top of the list. From arc welders to Zeppelins, helium has several notable uses,¹ but none are more recognizable than the simple helium balloon. What child has not been fascinated by a balloon’s unusual ability to float against gravity? Little do they know that it is their first introduction to the lightest of the noble gases, and it is a rarer element than most people realize. Helium is, in fact, a very finite resource, and one that threatens to run out in the not-too-distant future. Luckily, new techniques are being developed to begin to search for helium deposits.

Helium tile from University of Waterloo
Periodic Table Project

Artwork by Louisa Putulik and Maani Ulujuk Ilinniarvik, Teacher: Katharine O'Connell, Rankin Inlet, Nunavut, Canada

To begin, let’s have a look at the elemental nature of helium. Even those already familiar with helium may find it a bit surprising how uncommon the element is on Earth, given the amounts produced by our sun. When the gravity of a star fuses two hydrogen atoms together it forms an atom of helium. This makes it the second most common element in the universe; only hydrogen is abundant.² Why then is helium not more available on Earth? Well to begin with, helium is so light that it easily floats above the heavier gases in Earth’s atmosphere. It can actually float straight out of the Earth’s atmosphere altogether and leak into space. There is however another reason that helium is hard to come by. It is that helium is inert. As a noble gas, helium is completely unreactive and will not form molecular or ionic bonds. It has hardly any attraction to other chemicals, making it very difficult to trap on Earth. Hydrogen, while smaller than helium, is quite reactive. Hydrogen is found in water, most organic substance and many other compounds, making for plenty of Earthly hydrogen sources.

This poses the question, if helium is so hard to keep a hold of, where on Earth do we get the helium for our balloons? Earthly helium doesn’t come from nuclear fusion (stars) but from nuclear fission. Radioactive elements such as uranium will sometimes

emit alpha-particles as they decay. These alpha particles have two protons and two neutrons, so they are essentially a helium nucleus without electrons. If we are lucky, this process will be occurring within the Earth’s crust, ideally within a geological formation that can trap the helium. In the past, helium was obtained from the same wells that were used to obtain oil or gas, a valuable leftover that could be exploited for some extra profit.³ No one was looking speficially for helium. However, with a high demand for helium and the possibility of a shortage on the horizon, some groups are researching new methods for hunting down this rare gas.

Now companies like Helium One are on the look-out for new sources of helium.³ With help from researchers at the University of Oxford and the University of Durham they have made a very impressive find. This team of researchers has developed a new method for finding helium, and it has already been used to discover a massive source in the Tanzanian East African Rift Valley. The new method starts with identifying Goldilocks’ Zones for helium — looking for volcanic activity with the type of geological structures that would be able to trap the gas. Extreme temperatures caused by volcanic activity can free the helium that is sometimes trapped in an inaccessible form within mineral deposits in the Earth’s crust. This allows it to accumulate closer to the surface. This appears to be exactly what occurred in Tanzania, where helium gas can be found bubbling out of the ground.⁴ The link of volcanic activity and surface helium deposits works both ways. Measuring helium emissions is actually a good way to track and forecast volcanic eruptions. The unreactive nature of helium makes it an almost ideal geochemical indicator.⁵

Experts have calculated that the discovered gas deposit in Tanzania contains about 54 billion cubic feet of the gas, which seems a lot more impressive when you consider that the annual consumption of helium worldwide is only about 8 billion cubic feet.⁴ The researchers feel confident that this method can be used to locate other sources, so it is possible that the days of finding helium by chance are behind us. With help from skilled geochemists and earth scientists, companies like Helium One will hopefully be keeping us supplied with helium for some time to come.

Authors Note

When writing this article, I thought it was safe to say that no helium compounds existed, but it may have been more accurate to say that no natural helium compounds exist. In a paper titled “A stable compound of helium and sodium at high pressure” published by Nature Chemistry on February 6th, a team of scientists from Utah State University claims to have created Na₂He in a diamond anvil cell at around 1.1 million times the pressure of Earth’s atmosphere. This is the first time any He compound has been made!⁶

Student questions

1. What is it that makes helium and other noble gases so unreactive?
2. If 1 cubic foot equals approximately 0.0283 cubic meters, what is the annual consumption of helium worldwide in kilolitres? Answer:2 x 10⁸ kL
3. Uranium-235 decays to produce He-4 and what atom? Write out this nuclear reaction.
4. What is He-4 with no electrons commonly referred to as? What is the charge on this particle?
5. [Research] Stars will begin to fuse helium atoms together once they are low on hydrogen. What other elements are produced via fusion in stars?
6. [Research] Helium is a monoatomic gas at room temperature. At what temperature does helium become a liquid? What are some properties of liquid helium and how can we use it? (Hint: think hospital.)
7. If we were to experience a helium shortage, are there any other chemicals that have similar properties? What are the advantages to using helium instead?

References

(retrieved Feb 2017)

1. T. Lougheed, An uplifting element | The Chemical Institute of Canada, 2015, www.cheminst.ca/ magazine/feature-story/uplifting-element
2. Abundance in the Universe for all the elements in the Periodic Table, 2016,
   periodictable.com/Properties/ A/UniverseAbundance.html
3. Description of Helium – Helium One, 2016,
   www.helium-one.com/helium/description-of-helium/
4. Huge helium discovery 'a life-saving find' | University of Oxford, 2016, www.ox.ac.uk/news/2016-06-28-huge-helium-discovery-life-saving-find
5. Helium gas heralded underwater volcano eruption www.earthchangesmedia.com/helium-gas-heralded-underwater-volcano-eruption
6. X. Dong et al. "A Stable Compound Of Helium And Sodium At High Pressure", Nature Chemistry 2017: n. pag. Web. 8 Feb. 2017.