One of the most valuable assets owned by Lancaster University is stored in beer kegs. But it's not in one of the student bars. In a carefully locked laboratory rows of metal kegs are arranged on shelves and linked together with spindly copper pipework. The containers aren't loaded with prize beer but rather a gas called helium-3, one of the most expensive materials in the world. A single litre costs roughly $2,000 (£1,500), though the price can fluctuate. "The lab has been going for 50 years or