Helium is the second-lightest element. Although it is rare on Earth, you likely have encountered it in helium-filled balloons. It's the most widely used of the inert gases, utilized in arc welding, diving, growing silicon crystals, and as a coolant in MRI (magnetic resonance imaging) scanners.

In addition to being rare, helium is (mostly) not a renewable resource. The helium that we have was produced by the radioactive decay of rock, long ago. Over the span of hundreds of millions of years, the gas accumulated and was released by tectonic plate movement, where it found its way into natural gas deposits and as a dissolved gas in groundwater. Once the gas leaks into the atmosphere, it is light enough to escape the Earth's gravitational field so it bleeds off into space, never to return. We may run out of helium within 25–30 years because it's being consumed so freely.

Why We Could Run out of Helium

Why would such a valuable resource be squandered? Basically, it's because the price of helium does not reflect its value. Most of the world's supply of helium is held by the United States National Helium Reserve, which was mandated to sell off all of its stockpile by 2015, regardless of price. This was based on a 1996 law, the Helium Privatization Act, which was intended to help the government recoup the cost of building up the reserve. Though the uses of helium multiplied, the law had not been revisited, so by 2013 much of the planet's stockpile of helium was sold at an extremely low price.

In 2013, the U.S. Congress did re-examine the law, ultimately passing a bill, the Helium Stewardship Act, aimed at maintaining the helium reserves.

There's More Helium Than We Once Thought

Recent research indicates there's more helium, particularly in groundwater, than scientists previously estimated. Also, although the process is extremely slow, ongoing radioactive decay of natural uranium and other radioisotopes does generate additional helium. That's the good news. The bad news is that it will require more money and new technology to recover the element. The other bad news is that there isn't going to be helium that we can get from the planets near us because those planets also exert too little gravity to hold the gas. Perhaps at some point, we may find a way to "mine" the element from gas giants further out in the solar system.

Why We Aren't Running out of Hydrogen