Gases for Life
TECHNOLOGY
Nitrogen and helium for cutting-edge research
By Marcos Torcal and Marion Riedel, Messer Ibérica de Gases
Synchrotron light allows the tiniest details of matter to be investigated on the atomic and molecular level, paving the way for scientific advances, including in biomedicine, materials science and archaeology. The ALBA Sincrotrón science facility uses helium cooling in a range of equipment and apparatus.
Gases for Life
TECHNOLOGY
Nitrogen and helium for cutting-edge research
By Marcos Torcal and Marion Riedel, Messer Ibérica de Gases
Synchrotron light allows the tiniest details of matter to be investigated on the atomic and molecular level, paving the way for scientific advances, including in biomedicine, materials science and archaeology. The ALBA Sincrotrón science facility uses helium cooling in a range of equipment and apparatus.
Scientists from Salamanca and Amsterdam have found out how molecules at the boundary between the upper and lower layers of the human skin are connected to one another. A group of researchers from Barcelona and Belgium’s KU Leuven University have taken a major step in developing a new material for more efficient solar cells. It has also been possible to carry out a very detailed non-destructive examination of the chemical composition of medieval human bones discovered in a church in Herzegovina.
Aerial photograph of the ALBA Sincrotrón complex
Millions of times brighter than the sun
All of the aforementioned experiments – and the list of projects could go on and on – were carried out thanks to the synchrotron light generated by the ALBA Sincrotrón electron accelerator complex in Cerdanyola del Vallès near Barcelona, the only synchrotron light source in Spain. This science facility has eight laboratories which allow a wide variety of scientific fields and problems to be investigated. The spectrum ranges from infrared to high-energy X-rays. One of the biggest advantages is the extreme brightness of synchrotron light, which is millions of times brighter than the surface of the sun. This level of intensity allows extremely high resolution and facilitates observation of very short-lived phenomena such as chemical reactions.
ALBA Sincrotrón is the most complex science facility in Spain. Standing out among the different elements essential for its operation are the superconducting magnets that are used in one of the facility’s light lines (BOREAS, to investigate the magnetic properties of materials) as well as in one of the loaders for storage rings. For these magnets to work properly, they have to be cooled with liquid helium at a temperature approaching minus 270 degrees Celsius.
Although helium is the second most common element in the universe, there are limited reserves of it on earth. Obtaining it – mainly from certain gas fields – is a laborious and expensive business.
Saving energy through helium recycling
Since some of the gas evaporates during the process of cooling the magnets, ALBA teamed up with the Catalan Institute of Nanoscience and Nanotechnology (ICN2) to install a facility that liquefies the gaseous helium again. This allows up to 80 per cent of the gas to be recovered. This in turn significantly reduces both the operating costs and the environmental impact. ALBA’s helium recovery facility has an annual recycling capacity of 25,000 litres of liquid helium.
However, liquefying helium is a particularly challenging task due to the element’s properties: it only cools down like other gases during expansion at atmospheric pressure below minus 233 degrees Celsius. Helium therefore has to be precooled to below this temperature before it can be liquefied using the usual cycles of compression and expansion. Cryogenic liquid nitrogen is used for the precooling process.
Messer replaced the previous gas supplier in 2019 after winning a tender. Since the synchrotrons operate around the clock, it was essential that there was no disruption of supply during the transition phase. During installation of the new nitrogen cryotank, a temporary supply was put in place which included a cryogenic vessel with a capacity of 16 tonnes, a cryogenic hose and the necessary special valves. The tank change was completed as planned and the scientists were able to continue their experiments without interruption.