My research focuses on how magnets behave when you make them very, very small. (The broad answer is: really interestingly and often unpredictably.) Like many people who study the physical world, it is much easier to get at the basic nature of a material if you cool the material to very low temperatures. Cooling literally "freezes out" many effects, making the system simpler to understand.
Our practical understanding of temperature is primarily the thermometer. We experience temperatures from maybe a few tens of degrees below zero Fahrenheit to 107 degrees°F (number picked because we actually hit that here in Texas last month.) On the Fahrenheit scale, freezing is 32°F and boiling is 212°F), while the Celsius scale sets freezing at 0°C and boiling at 100°C).
On a more fundamental note, however, temperature is actually a measure of molecular motion. The faster molecules move, the higher their temperature. This means that there is an absolute lower limit on temperature. The Kelvin scale, which often is more handy for scientists, is an absolute scale in that 0 K is the lowest possible temperature (corresponding to -459°F and -273°C). Zero kelvin corresponds to no motion, not even at the atomic level. Needless to say, we can't just cool things to 0K.
The last I heard, the world record lowest temperature is somewhere around 100 picokelvin (which is 0.0000000001 or 10-10 kelvin), but that's really overkill for me. Most scientists rely either liquid nitrogen (77 K) or liquid helium (4 K). You can get to slightly lower temperatures by pumping on these liquids. (PV=nRT), but throwing a little liquid helium in a dewar (a fancy thermos bottle) is by far the easiest way to cool samples and get rid of those annoying degrees of freedom that get in the way of understanding.
Of course, it's not that easy. Liquid helium (LHe) turns into a gas above 4K and liquid nitrogen does the same above 77K, so you can't just pour these cryogens from one container to another. You have to transfer LHe using vacuum lines and keep it in a dewar so that it stays cold. It's a minor pain to do so, but the results are well worth the trouble.
When we encounter Helium in the environment, it is naturally around as a gas. About 7% of the helium used each year is used for balloons, parade floats, etc. Helium is the second most abundant element in the universe, but it is present on Earth at a concentration of about only 5 parts per million. Helium is element number two on the periodic table – the second lightest element – and because it is so light, helium is easy to get moving fast, so it rapidly diffuses out of the Earth's atmosphere.
Helium is produced inside the Earth. When heavy elements (like uranium) radioactively decay in the Earth's crust, helium atoms are a by-product. Most of these atoms diffuse to the surface and escape the Earth, but some of the helium gas is trapped in the Earth the same way natural gas is. Helium is usually extracted in the process of natural gas processing, but since helium is a very small fraction of natural gas deposits (it varies from location to location, but often on the order of a percent or less), sometimes it isn't economically advantageous to bother with it.
The annual global use of helium is larger than the amount of helium produced each year. That seems impossible, but it is made possible by the fact that America controls the biggest store of helium gas in the world. Stored near Amarillo Texas are nearly a billion cubic feel of helium gas. The U.S. started the store in 1925 with the idea that we needed a reliable source of helium for blimps. (Helium, unlike hydrogen, is not flammable.)
By the mid 1990's, the Federal Helium Reserve was deeply in dept and the U.S. Congress decided that it should sell off the helium reserve and privatize the 'helium economy'. (The linked article notes that the debt was a paper debt – the Bureau of Land Management wasn't making enough money off selling helium to other parts of the government, but it was a good excuse to let private companies take over the market.) The reserve is supposed to be sold off completely by 2015.
In the last decade, helium prices have doubled – at least. I know that the price I pay for helium has risen rapidly. The graph below is from the National Academy of Science's report "Selling the Nation's Helium Reserves", just out this year. The pink line is the 'Grade A' price, which is the price of privately owned helium. The blue line is the Bureau of Land Management crude price.
Robert Richardson, Nobel laureate from Cornell for discovering superfluidity in the isotope helium-3, was the chair of a National Academy of Sciences study. Richardson believes the U.S. is squandering a precious resource.
It is always interesting to read different reports of an issue in different media outlets. Regardless of whether the article is from the American or European press, two quotes stand out in just about every article covering his interview with New Scientist. The first is that helium supplies will run out in 25 years. The second is that helium balloons for kids parties ought to cost $100 each.
Helium won't actually "run out", since the nuclear decay process is ongoing, and there are some potential processes to produce helium from radioactive decay of other elements; however, there isn't much practical difference between "run out' and "so expensive we can't afford it". The situation is going to be the same as with oil: as the price rises, it makes more and more economic sense for companies to separate it from the natural gas with which it is usually found; however, the price will likely rise very high.
You may think that's easy to compensate for: We can all just increase the 'supplies' budget line in our NSF grants; however, scientists are likely to not take the most significant hits. One-fifth of the world's helium supply is used in MRIs. The typical MRI requires superconducting magnets and, since we haven't figured out room-temperature superconductivity yet, they require liquid nitrogen or liquid helium to keep them in the superconducting state. Most systems use a closed cycle – helium cools the magnet, warms up in the process, turns to a gas, and is re-liquefied. A typical MRI magnet, however, requires 1700-2000 liters of liquid helium. Older models have to be refilled on a timescale from months to years, while newer models advertise that they "never" need to be refilled. (I'm about to buy a system like that. We'll see how long 'never' is.) MRI resolution gets better the larger the magnetic field. Larger magnetic fields require larger magnets and thus more liquid helium.
The situation is unlikely to get much better, as worldwide demand continues to rise. The graph at right (from the NAS book) shows a slight leveling off of US demand that has continued throughout 2008-2009 due to the economic recession; however, global demand more than made up for our plateau.
The Congressional act in 1996 mandated a review by the National Research Council and one was undertaken in 2000. That panel came to the conclusion that "privatizing the reserves should not adversely affect the production and use of the gas over the next two decades", although they did recommend some actions be taken to ensure that adequate supply would be available.
They also did what most committees that issue reports do: they recommended that there be another study in 10 years or "whenever there was some change in supply, demand or prices". That's the genesis of the study that Richardson co-chaired, which was released in August. It's very interesting to compare the tenor of the two reports. Having served on an NRC committee, I know that an awful lot of the tone of the report is determined by the people on the panel – despite the often-unappreciated work of the NRC staff trying to keep things as objective and even-keeled as possible.
The Earth is 4.7 billion years old and it has taken that long to accumulate our helium reserves, which we will dissipate in about 100 years. One generation does not have the right to determine availability for ever." – Robert C.Richardson
And, of course, I have to comment on the quote about kids' balloons costing $100. Richardson was trying to make the point that if the price of helium were determined on an open market, the cost would be so high that that's what the amount of helium in a balloon would cost. One of Richardson's main points is that helium prices have been artificially low, they shouldn't be, and therefore the US is losing an opportunity to make money off this resource. A lot of outlets used this comment in their headlines or taglines, but the gist was more of as a warning to parents and kids, or it came off as a comment that sort of suggested that helium was too precious to be used in trivial applications like balloons and scientists were killjoys who wanted all the helium for themselves.
I was never trained to conserve helium – it was cheap and it was fun to watch the giant plumes of white vapor rising from the 100-liter stainless steel dewars. We weren't purposefully wasteful, but we also didn't go out of our way to minimize how much we used. In Europe – and increasingly in the U.S. – buildings are being designed to recover as much helium as possible and re-liquefy it. Recovery and liquefaction is an expensive process, but (as is the case in many contexts) people become interested in conservation only when it becomes expensive to be wasteful.
5 thoughts on “helium: a weighty question”
As you may be aware, I was the primary NRC staff person for middle and end phases of the 2000 study. Let’s just say that the process of getting consensus on that report was very interesting.
I just scanned the committee biographies for the second study and am struck by how different committees are in terms of representation and size. The second committee is more than twice the size of and has a larger proportion of helium users on it than the first study.
Those factors probably account for the majority of the differences in tone.
Out of curiousity, when you say: “The annual global use of helium is larger than the amount of helium produced each year.” do you mean produced as in the total annual amount of helium produced inside the Earth by radioactive decay, or the total amount captured annually for human use by the various natural gas drilling companies?
Neat. I’m a bioscience person and I’ve never been particularly brilliant in the physical sciences, but temperature has always captured my interest. I’ve got a question I’ve never been able to get answered, at least not definitively. Do you know if there is a maximum possible temperature? A temperature at which atoms not only break down, but their smaller components do as well? I guess a temperature at which matter ceases to exist or is so unstable it’s only able to exist as a collection of subatomic particles is what I’m thinking of. I know lightning can produce plasma with temps nearing 30,000 K, so what happens at 10 or 100 times that? Do you know the maximum temp humans have measured/created in an experiment? Would love to see a future post on this or even just a link to more information.
Hm, 100picokelvin seems small for regular old temperature. I think that might be a spin temperature, and probably if there’s a temperature achieved on the order of 100pK, then there’s also one on the order of -100pK, which should be the hottest temperature on record.
it was cheap and it was fun to watch the giant plumes of white vapor rising from the 100-liter stainless steel dewars
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