The newfound structure lies about 49,000 light-years from the galaxy's center, and one of the arm's many large molecular clouds contains an amount of molecular hydrogen equivalent
to that of 50,000 suns.
It is also estimated that, compared to a litre of petrol, this hydrogen equivalent
will cost around 80p, with further reductions likely once the technology is widely in use.
The capacity of Teesside's underground storage, developed by ICI for the petrochemical industry in the 1960s, amounted to "the hydrogen equivalent
of one million gallons of petrol," Dr Roddy said.
For starters, a single pound of nuclear fuel can provide the hydrogen equivalent
of 250,000 gallons of gasoline, with zero carbon emissions.
The cost of hydrogen is also about four times too high today, he said, noting that the 2010 goal is to bring down the cost of the hydrogen equivalent
of a gallon of gas to $1.50 by developing diverse methods of production.
In other words, for every 100 energy units (such as joules or BTU) of heat obtained from sunlight, an amount of hydrogen equivalent
to 25 energy units (of fuel energy) can be obtained.