Author Topic: Hydrogen powered equipment  (Read 3292 times)

Offline A_M_Swallow

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8599
  • South coast of England
  • Liked: 375
  • Likes Given: 167
Re: Hydrogen powered equipment
« Reply #20 on: 11/06/2018 08:58 pm »

Don't forget politics has various sides. Some care about reducing CO2 and some do not. If all politicians listened to scientists and engineers then they would make logical decisions.

Since this is a propaganda exercise someone from public relations can show the politicians:
* hydrogen launcher - SLS
* hydrogen first stage - Centaur from ULA
* hydrogen small lunar lander - MX-1 from Moon Express (hydrogen peroxide)
* hydrogen heavy lunar lander - Xeus from ULA and Masten

A fuel cell powering something will complete the set.

Offline DreamyPickle

  • Full Member
  • **
  • Posts: 220
  • Home
  • Liked: 93
  • Likes Given: 21
Re: Hydrogen powered equipment
« Reply #21 on: 11/07/2018 10:02 am »
The impact of rocket fuels on global warming is relatively small. The reason so many people are in favor of a "carbon tax" is that it would impact industries proportional to their fuel use rather than chaotic public pressures.

For rocketry the cost of the propellant is such a small component that even extremely large taxes on fuel would not warrant a switch.

However "hydrogen powered equipment" was proposed as part of exploration missions, this makes a lot more sense because there it competes against batteries. But I don't know if anyone studied this closely and the difficulty of storing cryogenic fuels in a rover-like form factor might offset the greater energy density.

Offline speedevil

  • Senior Member
  • *****
  • Posts: 3213
  • Fife
  • Liked: 1664
  • Likes Given: 1973
Re: Hydrogen powered equipment
« Reply #22 on: 11/07/2018 12:08 pm »

However "hydrogen powered equipment" was proposed as part of exploration missions, this makes a lot more sense because there it competes against batteries. But I don't know if anyone studied this closely and the difficulty of storing cryogenic fuels in a rover-like form factor might offset the greater energy density.
That depends rather how you define rover.

However, a useful point to note is that commercial off-the-shelf dewars can store 30l, with a mass of 15kg, in an office environment for over 6 months, for around $1000.

Methane is so much denser than hydrogen (10*), that even if you need to reform it before going to a fuel cell, it may be worth it, as it shrinks your tank mass.

Clearly - in some places, methane is going to be a lot harder to make, and hydrogen may win solely for that.

Offline lamontagne

  • Full Member
  • ****
  • Posts: 1461
  • Liked: 1927
  • Likes Given: 309
Re: Hydrogen powered equipment
« Reply #23 on: 11/07/2018 12:19 pm »
Don't know about other companies, but Musk has mentionned that they will be producing their methane from solar, as soon as they can.  Once you have the hydrogen, producing the methane from CO2 does not take much energy.  Almost all of the energy goes into the electrolysis.  CH4 holds less energy than H2, after all.
If BFR phases out the smaller vehicles, then the real energy source for the BFR system would be solar.  Can't be much greener than that.

Offline speedevil

  • Senior Member
  • *****
  • Posts: 3213
  • Fife
  • Liked: 1664
  • Likes Given: 1973
Re: Hydrogen powered equipment
« Reply #24 on: 11/07/2018 12:40 pm »
Don't know about other companies, but Musk has mentionned that they will be producing their methane from solar, as soon as they can. 
At the above mentioned efficiency of 50%, and assuming you get out oxygen for free, as seems reasonable, to provide power to replace all F9 and add starlink launches means at some 1000 tons of methane per launch, somewhere not too far off 50ktons/year of methane.
2*10^15J, or 60MWav.
Some 200MW worth of fixed orientation panel - or a little over a kilometer in diameter of panels.

This is equivalent to two quarters worth of production at solarcity levels.

I note the obvious business opportunity for them to branch out mass producing earthly ISRU, if they can get the cost down enough, which would have obvious benefits for Mars.
Storing energy as methane is nearly trivial, compared to the expense of batteries.
(yes, losses of >50% are significant)

Offline Norm38

  • Full Member
  • ****
  • Posts: 1198
  • Liked: 594
  • Likes Given: 850
Re: Hydrogen powered equipment
« Reply #25 on: 11/07/2018 05:26 pm »
Hydrogen isn't a fuel, never has been, as there's nowhere to get it.  It is an energy storage mechanism.  And given the efficiency losses in producing it, it makes absolutely no sense to power anything off hydrogen that can be powered from electricity.
That's why hydrogen fuel cells never took off while Tesla is succeeding.  Build a bunch of electrical generation, hydrogen production facilities, pipelines or tankers, distribution infrastructure and stations to fill up.
Versus everyone plugs their cars into an outlet with a much higher efficiency.

Offline ncb1397

  • Full Member
  • ****
  • Posts: 1304
  • Liked: 567
  • Likes Given: 6
Re: Hydrogen powered equipment
« Reply #26 on: 11/07/2018 06:03 pm »
Hydrogen isn't a fuel, never has been, as there's nowhere to get it.  It is an energy storage mechanism.  And given the efficiency losses in producing it, it makes absolutely no sense to power anything off hydrogen that can be powered from electricity.
That's why hydrogen fuel cells never took off while Tesla is succeeding.  Build a bunch of electrical generation, hydrogen production facilities, pipelines or tankers, distribution infrastructure and stations to fill up.
Versus everyone plugs their cars into an outlet with a much higher efficiency.

Way oversimplified analysis. Energy efficiency doesn't matter to consumers, what matters is cost which factors in energy consumption but is not the sole factor. Well, that and experiential factors like ease of use and convenience. And on that basis, something like the Hyundai Nexo at a cost of $62,000 would be a perfectly legitimate choice over a Tesla Model X 100D with somewhat equivalent range at $99,500 (360-80 miles vs 295 miles). Per mile fuel costs are hardly an overwhelming factor. Supercharging rates in California are 26 cents yielding a per mile cost of about 8-9 cents. At home charging prices are 18 cents per kilowatt or a per mile rate of 6 cents per mile (let's just call it 7 cents average). Hydrogen costs in the same market are about $14 yielding a per mile cost of about 21 cents. The break even point derived from the 14 cent per mile spread is therefore 270,000 miles. That's essentially car end of life.

I don't know, we will see what happens. But the main point is that nobody is buying cars based on the energy efficiency sticker. ICE cars are still stomping on electrics, and so the whole thesis that energy efficiency is going to be the determining factor is suspect. And it isn't like fuel cell cars or hydrogen production efficiency can't improve - which we have already seen when comparing the Nexo vs the Mirai.

Anyways, bringing this back to the forum's purpose so this doesn't get locked, I figured that a fuel cell lunar rover was superior to an electric because it could provide a significant portion of global access without charging stations all over the moon. For that reason alone, I hope that fuel cells on earth find their niche to provide the technology and industrial base to make that happen. If not in cars, then perhaps in airplanes (or maybe just in military vehicles as they might care about CO2 emissions, but fuel pricing might not be a huge factor).
« Last Edit: 11/07/2018 06:42 pm by ncb1397 »

Offline SherryWArredondo

  • Member
  • Posts: 1
  • Toronto
  • Liked: 0
  • Likes Given: 0
Re: Hydrogen powered equipment
« Reply #27 on: 01/18/2019 06:42 am »

There are hydrogen fuel cell trains already operating in Germany.

Yes. I was reading about it here: https://www.hydrogenics.com/hydrogen-products-solutions/fuel-cell-power-systems/hydrail/developments-in-hydrail/ . It's running in Germany now. But are they are not available for commercial service? Is any other country other than UK and Germany planning it?
« Last Edit: 01/18/2019 08:06 am by SherryWArredondo »

Tags: