Re:Ask HN: Is hydrogen likely to be a major source of power ...
by akira2501 on Wednesday September 23, 2020 @08:28PM
(#24573953)
> Even in rockets, where weight is extremely critical, SpaceX chose to use kerosene/methane due to the problems of working with LH2 (very low density, very cold temperatures, hydrogen embrittlement).
That and they have very few missions where the increased ISP from LH2 would actually benefit them. The other upside of LH2 and LOX is that you can run it in engines, but you can also run it in fuel cells directly and generate a surprising amount of electricity from a very small package -- the other benefit there is that the Fuel Cells produce pure water as a byproduct.
The Space Shuttle had three fuel cells which provided more than enough power for a full mission. Most missions could be run on two without any compromises. Also, when it was visiting the ISS, it was a convenient means of supplying water to the station.
On non ISS missions, so much water is generated that they have to dump it overboard.
That and they have very few missions where the increased ISP from LH2 would actually benefit them. The other upside of LH2 and LOX is that you can run it in engines, but you can also run it in fuel cells directly and generate a surprising amount of electricity from a very small package -- the other benefit there is that the Fuel Cells produce pure water as a byproduct.
The Space Shuttle had three fuel cells which provided more than enough power for a full mission. Most missions could be run on two without any compromises. Also, when it was visiting the ISS, it was a convenient means of supplying water to the station.
On non ISS missions, so much water is generated that they have to dump it overboard.