Sustainable use of helium thanks to the Helium Recovery System
Within the Faculty of Science at Radboud University, approximately 60,000 litres of liquid helium are used annually to conduct experiments at very low temperatures. Liquid helium is also used to cool various superconducting magnet systems.
However, the supply of helium on Earth is finite: everything that goes into the air is permanently lost. In addition, the market price of liquid helium has more than doubled in the past year and has risen to 20 euros per litre. Under the leadership of the TechnoCentre and HFML-FELIX, the helium recovery system has therefore been installed on the Radboud University campus.
The helium recovery system is a completely closed pipe system of many hundreds of meters to collect the vaporised helium from the experiments in gaseous form and transport it to the high-pressure gas storage at HFML-FELIX. At HFML-FELIX, the helium gas is then liquefied again with a liquefier. The liquid helium can then be transported in mobile vessels to the various research facilities within the faculty. This closed system ensures the most sustainable and optimal reuse of the increasingly scarce helium.
During the experiments or due to leaking components, the helium gas sometimes gets mixed with other gases. However, only helium with a purity percentage of more than 99% can be reused in the liquefier. In order to be able to measure and monitor purity, the TechnoCentre has developed a compact measuring system in collaboration with HFML-FELIX in which these functions are integrated. The monitoring system shows from where and with what purity the helium is returned. If the helium gas is too polluted, an alarm is activated and this polluted gas is automatically vented to the atmosphere; only sufficiently pure helium gas is liquefied again for reuse. Every year, more than 95% of the liquid helium used in the experiments is reused.