Compressed hydrogen – A fuel for the future? Dr Roy Irani explains in part 1 of a new series exploring gases in the 21st century.
Hydrogen is the lightest gas, has the smallest atom and is the most abundant element in the universe (almost 75 at .%). Almost every day we hear how hydrogen is going to be our saviour in terms of fuel for the future. The main reason for this optimism is its clean combustion by-product (namely water) and the very high resultant energy (due to the highest electron/neutron ratio). Yet isolating hydrogen, using it and storing it, all present monumental challenges in the practical world.
It is still cheaper to use oil even at well over $100 per barrel, than to separate hydrogen from its compounds such as water or natural gas. Using hydrogen needs precise procedures due to the high flammability risks it presents.
As for storing it, which can be as a compressed gas, a cryogenic liquid or in metal hydrides, none of the current solutions are yet economic, despite a huge effort being devoted in these areas. In fact, the current emphasis seems to be concentrating on storing hydrogen in its compressed form, since its low liquefaction temperature of 20K consumes a lot of energy for its formation and preventing evaporation is expensive – whilst the area of metal hydrides is very much in the research stages.
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