Conserving a Valuable Resource: System Will Recover Helium for Physics Lab Use
Pitt’s new physics department helium recovery system will put the campus at the forefront of U.S. university efforts to conserve the finite supply of this increasingly expensive laboratory gas.
With U.S. helium reserves being sold off and prices rising, Pitt has used the National Institute of Standards and Technology-funded renovation of mid-campus physics buildings, undertaken over the past five years, as an opportunity to install a new helium recovery system. It should be able to reliquefy at least 90 percent of the gas currently used and allow for experiments that might not otherwise have been affordable, says Patrick Irvin, faculty member in the Department of Physics and Astronomy. Irvin serves as the unofficial department representative for the recovery project, answering questions from primary investigators and offering faculty technical advice on its future use.
Physicists use helium, a by-product of natural gas wells, as a refrigerant to conduct experiments at very low temperatures. Its boiling point is 4.2 degrees Kelvin (about 460 degrees below zero). But when the gas is under extreme pressure it becomes liquid and can freeze items quickly. Irvin, for instance, cools special metallic alloys to make them superconductive, so that they become powerful, permanent electromagnets and he can examine the quantum mechanical properties of electrons.
But the gas comes at a cost. "You can easily spend tens of thousands of dollars a year using helium," he says. While Congress voted not to close the U.S. (and world’s only) helium reserve as planned last year, helium has doubled in price over the past decade to $12.50 a liter, according to the journal Nature, and the cost is expected to rise an additional 50 percent due to decreasing supplies.
Part of the problem is the amount of the gas that is lost. "Helium will leak through everything," Irvin says. Not only does the gas escape during experiments or when a superconducting magnet suddenly fails, it also leaks from delivery pipes, escaping into the atmosphere.
Pitt’s new system is expected to reduce that leakage in addition to allowing used helium to be reused. By early winter, the new system will pipe used helium from physics labs in three of the renovated buildings — Old Engineering Hall, the Nuclear Physics Laboratory and Allen Hall — to a balloon-like container that repressurizes and thus reliquefies it. Two-inch copper pipes to deliver the helium from experimental equipment to the central liquefaction spot already have been installed in all three physics facilities. The only cost of running the equipment, after the $3.9 million budgeted in March by Pitt trustees for its purchase and installation, will be the cost of electricity to fuel the compressor.
Ivin says: "The recovery project at Pitt should serve to insulate existing users from spikes in the price due to uncertainty of supply, which hopefully will enable research that wouldn’t have taken place because it would not have been affordable.
"It’s my hope that this will be available to other departments," he concludes. "There’s a lot of capacity in the liquefaction that is being installed, relative to the use of physics. You could liquefy an awful lot more helium than we use in physics."
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