Spaceships series: Electrical Batteries module?

[DaltonS]

In a perfectly efficient fuel cell or MHD turbine setup, one ton of water should be produced (BTW how do we store that? Do empty tanks have a launch mass?) for each ton of LOH fuel used. Using a "chemical refinery" (SS1 p.19) to crack it back, an SM+x system should process one SM+x tank in 3 hours (if x is odd) or 3h20m (if x is even) for one power point. This is VERY surprising because according to SS1 p.20 a fuel cell produces 12 PPh (Power Point hours) per fuel tank at TL7, 24 PPh/tank at TL8, 48 PPh/tank at TL9 and 96 PPh/tank at TL10+ (an MHD turbine has the same efficiencys at TL9 and TL10+). That's an energy output that is 4 to 32 times the energy input! What ever happened to TANSTAAFL?

Dalton "how do I submit this to Murphy's Laws?" Spence

[Flyndaran]

The issue is that nearly everyone considers the production facilities and refineries/mining to be grossly over powered. At least one or two Spaceship issues suggest dividing their outputs by 24, if I remember correctly.

[Ulzgoroth]

Originally Posted by Flyndaran

The issue is that nearly everyone considers the production facilities and refineries/mining to be grossly over powered. At least one or two Spaceship issues suggest dividing their outputs by 24, if I remember correctly.

Unfortunately even with that you're getting an efficiency out of the closed loop of 32/24 > 1 at TL10+.

[Flyndaran]

Originally Posted by Ulzgoroth

Unfortunately even with that you're getting an efficiency out of the closed loop of 32/24 > 1 at TL10+.

Who's using fuel cells at TL10+? I might cap the technology at TL 8.

Batteries or at least capacitors are nice for the enormous but very short lived burst of power needed for exotic modules.

[DaltonS]

Originally Posted by Ulzgoroth

Unfortunately even with that you're getting an efficiency out of the closed loop of 32/24 > 1 at TL10+.

And that's assuming TL10+ fuel cells/MHD turbines are 100% efficient at extracting energy from LOH. Does anyone know how efficient current fuel cells are?

Dalton "I still think it makes a good Murphy's Laws submission" Spence

[Anthony]

Originally Posted by DaltonS

And that's assuming TL10+ fuel cells/MHD turbines are 100% efficient at extracting energy from LOH. Does anyone know how efficient current fuel cells are?

Wikipedia does. Basically, any improvement past TL 8 is a function of more tank mass, not efficiency gains.

It is possible to estimate the value of an energy point from performance stats. Looking at a 100 ton (SM +6) ship:

Ion Drive: thrust = 100 lbf or 450N, vEx = 60 mps or 96 kps, power = 21.6 MW.
Mass Driver: thrust = 2000 lbf or 9000N, vEx = 96 kps, power = 43.2 MW.
Weapon, Major Battery: 30 MJ beam output, rate of fire 1/20 (1/10 if 'improved'), power output 1.5 or 3 MW.

Now, a fuel cell is 1 ep. The energy content of LOx/LHd fuel is about 15 MJ/kg, so with the entire volume filled with fuel (4,500 kg) total energy available is 18.75 MWH.

It is likely part of the problem here is the drives, since that's a power density of ~5 kW/kg for the ion drive, ~10 for the mass driver, and thus requires ~10 kW/kg for a TL 8 nuclear reactor, which is at least an order of magnitude too high. If we reduce power to a merely optimistic 1 kW/kg, reduce MD thrust by a factor of 10, and ion drive thrust by a factor of 5, we can justify an hour or two at TL 8, except that fuel cells have nothing like that power density (they don't even have a tenth that).

[Ulzgoroth]

Originally Posted by Flyndaran

Who's using fuel cells at TL10+? I might cap the technology at TL 8.

People who want to build net-output perpetual motion machines, apparently.

Originally Posted by Anthony;1396200[url=http://en.wikipedia.org/wiki/Fuel_cell

Wikipedia[/url] does. Basically, any improvement past TL 8 is a function of more tank mass, not efficiency gains.

Well, that is directly irreconcilable with Spaceships then.

[Trachmyr]

I posted some stats for Capacitors and Beta-Voltaic cells in this Thread.

[jacobmuller]

Originally Posted by DaltonS

In a perfectly efficient fuel cell or MHD turbine setup, one ton of water should be produced (BTW how do we store that? Do empty tanks have a launch mass?) for each ton of LOH fuel used. Using a "chemical refinery" (SS1 p.19) to crack it back, an SM+x system should process one SM+x tank in 3 hours (if x is odd) or 3h20m (if x is even) for one power point. This is VERY surprising because according to SS1 p.20 a fuel cell produces 12 PPh (Power Point hours) per fuel tank at TL7, 24 PPh/tank at TL8, 48 PPh/tank at TL9 and 96 PPh/tank at TL10+ (an MHD turbine has the same efficiencys at TL9 and TL10+). That's an energy output that is 4 to 32 times the energy input! What ever happened to TANSTAAFL?

Since S7 solved factories by saying days not hours, would mining/refining be solved by something like output/50 per hr, cost of system /10. Then upping output and cost for each TL to 10, eg TL8 CF+2 +10% output; TL9 CF+4 +25% output; TL10 CF+9 +50% output.
Put simply, instead of output per hour, output per 48hrs at TL7, to per 36hrs at TL10.
Although, if the numbers in mining/refining are right, that'd make all the power systems wrong (brain melting)

[Anthony]

Originally Posted by jacobmuller

Although, if the numbers in mining/refining are right, that'd make all the power systems wrong (brain melting)

The fuel cell numbers are most certainly wrong.