Fuel cell

[Jono as 2234]

Watching the patrick laine you tube channel, i saw he used a fuel cell, no solar, wind or generator. This is completely new to me. Has anyone experience with this technology?

[JoeM128]

I know fuel cells are used routinely on spacecraft but interestingly a friend of mine did the Mini TransAt race which stated in France and ended in Brazil in a 27’ designed to a “box rule”

Part of his electrical system included a fuel cell as he had no engine to charge conventional batteries. Just solar and the fuel cell.

Joe
SV Sirena Bella
J44

[Adelie]

Fuel cells are not ready for prime time yet, perhaps never on land.

On a boat their use looks even bleaker.

On land you can obtain the hydrogen but it has to be compressed or liquified and including storage containers the specific energy and energy density are the same or slightly better than LiFePo batteries.

If you are at a marina daily, using shore power to recharge batteries is going to be a small fraction the cost of refilling hydrogen storage from a fuel dock or where ever.

If you are underway and want to use solar to electrolyze water to get hydrogen, then specific energy & energy density get even worse because the equipment to electrolyze and then compress the hydrogen, both of which add mass to the system and take up volume. Worse they use significant power to do both, each uses about 15% of energy of the hydrogen. The best current fuel cells are about 60% efficient. Adjusting to the losses for electrolyzing and compressing the hydrogen net energy efficiency is in the 30-40% range, that is you get back out 30-50% of the energy you put in. LiFePo is 90-93% efficient.

Chemical storage of hydrogen is the only likely solution to better specific energy and energy density. There are various candidates such as hydrates.

The theoretical maximum efficiency of fuel cells is about 80%. Even if there was no energy cost to chemical storage you still have a 15% penalty to electrolyze it so the best overall power efficient you could ever get would be 70% vs the 93% of LiFePo. If you could store sufficient hydrogen for 100nm or more of range at 4-5 time the specific energy and energy density of batteries the it would be worthwhile but that depends on chemical storage maturing.

More likely are electro-fuels: fuels created from water and air using electricity. Ammonia, methanol, butanol, synthetic gas/petrol or synthetic diesel. I’m betting on butanol which is not as toxic as ammonia or methanol, has 70% the energy density and 80% of the specific energy or gas or diesel. Ammonia and methanol trail significantly in both measure. Butanol is a direct replacement for gas in engines. I haven’t seen studies on the relative power efficiencies of these fuels.