Produce water as a waste product
(handy as astronauts can drink it
USES
Cars
Why are they used?
No greenhouse gases are produced,
unlike with fossil fuels
Slows global warming
Fossil fuels are non-renewable
Earth has a lot
of of water
Spacecraft
Pollution
Although they produce no greenhouse
gases, they have extremely poisonous
catalysts, which have to be disposed of
The production of hydrogen gas requires a lot
of energy itself - it is mostly manufactured
using fossil fuels, which ruins the point of
making a car emission-free in the first place!
Although hydrogen can be made
through the electrolysis of water, this
requires electricity which is still mostly
obtained through the use of fossil fuels
My opinion
I think that fuel cells are certainly a step towards
ending the problem of global warming, but at the
moment they are almost pointless as their
production contributes just as much to global
warming as they would if they were petrol engines.