10-04-2014, 02:37 PM | #11 |
Join Date: Sep 2007
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Re: Closed Cycle Hydrogen Fuel Cell Question
There's quite a lot of hydrogen storage in the real world, pressurized and cryogenic. There are hydrogen pipelines (over a thousand miles worth in the US). Trucks to deliver the stuff commercially. There are solar-hydrogen power plants that have to store hydrogen on a seasonal basis (six months or so). It's not quite that bad, even at TL 8.
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10-04-2014, 02:45 PM | #12 | |
Join Date: Aug 2007
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Re: Closed Cycle Hydrogen Fuel Cell Question
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10-04-2014, 03:16 PM | #13 |
Join Date: Jun 2006
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Re: Closed Cycle Hydrogen Fuel Cell Question
There are two quite different issues here.
Hydrogen atoms will leak through most containers eventually, but not really all that fast. This is a problem that makes it hard to hold hydrogen under pressure for years, but is pretty negligible on the scale of days. The other is the rate at which heat leaks into containers full of liquid hydrogen and boils it, which requires you to vent the gas to prevent the container from bursting. The best anybody can do there is in the percent or two boil off per day range, and it's way faster than that for stuff like the shuttle tank, which is after all not well insulated since insulation would add weight.
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10-04-2014, 04:08 PM | #14 |
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Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
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Re: Closed Cycle Hydrogen Fuel Cell Question
Aerogel wouldn't add that much weight and insulate much better than any other modern material.
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10-04-2014, 04:11 PM | #15 |
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Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
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Re: Closed Cycle Hydrogen Fuel Cell Question
I consider fuel cells' main advantages to be reliability, efficiency, safety, and relative simplicity, with weight already sailed away compared to most other ways to produce energy.
I would have no problem with some loss for reusable hydride storage.
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11-09-2014, 02:06 PM | #16 |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: Closed Cycle Hydrogen Fuel Cell Question
Murphy’s Rules: I’ve heard of fuel efficiency, but…
Blurb: In GURPS Spaceships, at TL7 a Chemical Refinery (p.19) can produce 4× the rocket fuel that a Fuel Cell (p.20) needs to power it. Details: In GURPS Spaceships, a TL7 Fuel Cell (p.20) using hydrogen and liquid oxygen rocket fuel can produce 1 Power Point for three hours on internal fuel plus four times that (12 hours) for each fuel tank … which can filled by a Chemical Refinery (p.19) in 3 to 3 1/3 hours for 1 power point and a tank of water. Thus, each Power Point Hour of fuel cell energy can process up to four Power Point Hours worth of fuel. Since this is a closed system, if the fuel cell’s tanks are filled it can operate indefinitely and still provide power for other systems 72%-75% of the time. (And this is just at TL7; fuel cell efficiency doubles for each of the next three tech levels.) Dalton “Yeah, I know it's unrealistic, but that's the point!” Spence
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11-09-2014, 02:25 PM | #17 |
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Join Date: Oct 2004
Location: Forest Grove, Beaverton, Oregon
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Re: Closed Cycle Hydrogen Fuel Cell Question
That's an "artifact" of the Spaceships' rules. Factories produce at a far more than realistic rate, while the sub-optimal energy sources, like fuel cells, produce at a far more than realistic rate. Combining the two always results in obvious physics violations.
Fuel cells produce on the order of 1/10th what the real plants should, and solar should produce around 1/100th. Factories of all types should use rules like the 1/24 rate suggested in one or two supplements to keep from slamming out mega projects in absurdly short time frames.
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11-11-2014, 08:56 AM | #18 | ||
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: Closed Cycle Hydrogen Fuel Cell Question
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Note: Closed Cycle tanks for fuel cells should cost twice as much as regular fuel tanks, as they'd represent separate tanks for the Hydrogen-Oxygen fuel and the water produced. (Mass would remain the same, as one would empty as the other filled.) Dalton “BTW, what is a Power Point in kw/ton of ship?” Spence
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11-11-2014, 09:13 AM | #19 | |
Join Date: Mar 2006
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Re: Closed Cycle Hydrogen Fuel Cell Question
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Waiting for: Gurps VDS Gurps Armory (One can dream) ---- Per ardua ad astra "Through hard-work to the stars." |
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11-11-2014, 02:05 PM | #20 |
Join Date: Sep 2007
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Re: Closed Cycle Hydrogen Fuel Cell Question
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gurps, power points, spaceships |
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