Power with no nasty emission underwater or in enclosed spaces is very valuable. Hydrogen or ammonia fuel cells, Batteries or both to give range and endurance underwater is a significant advantage. Space travel is a example and a interesting one. "Launched in 1965, the Gemini V spacecraft was the first spacecraft to use fuel cells. These were PEM fuel cells developed specifically for the Gemini spacecraft by General Electric starting in 1962. Gemini 7,8,9,10,11 and 12 also used these fuel cells. The fuel cells were used as the main power
source, with silver-zinc batteries used for peak loads. Cryogenic hydrogen and oxygen tanks stored the reactants for the fuel cells.
The water produced by the fuel cells was used for drinking by the astronauts. "
The plans for putting people on Mars is mostly conditional on water
My ships had limited water supplies. 90 second showers for weeks on end while at sea. Wish we had used fuel cells just for the water
In Economics only the cost of those initial fuel cells was huge and the capacity was tiny! "Each fuel cell stack, illustrated in Figure 2, had 32 individual cells connected in series and produced 23 to 26 volts. Maximum power output per battery section was about one kilowatt. The fuel cells operated at about 65 °C"
Ballard Power fuel cells in Hydrogen trains are 1000s of times bigger and millions of dollars cheaper (in inflation adjusted terms)
Reservations of electrical engineers are clearly worth listening to. Storage and transport of Hydrogen and capacity, cost, maintenance and longevity of fuel cells all are factors needing careful consideration.
Have a great weekend
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