Ethane can be used as a refrigerant in cryogenic refrigeration systems. Liquid propellants involve cryogenic (liquid oxygen) or corrosive (nitric acid) oxidisers. It is a far cheaper source than a pressurized or cryogenic oxygen tank. The food undergoes a process of cryogenic freezing with liquid nitrogen. Evaporative cooling is commonly used in cryogenic applications. Niobium becomes a superconductor at cryogenic temperatures. Cryogenic liquid hydrogen is also used. These experiments mostly use either cryogenic or noble liquid detector technologies. They must be cooled to cryogenic temperatures during operation. Some additional precautions are necessary where ethane is stored as a cryogenic liquid. Liquid H is used in cryogenic research, including superconductivity studies. Liquefaction of gas is a power-intensive operation of cryogenic technology. Ethane is most efficiently separated from methane by liquefying it at cryogenic temperatures. The process works by tumbling and/or abrasively blasting the workpieces at cryogenic temperature levels. Cryogenic (or flash freezing) of food in liquid nitrogen can also be used.