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Complete Hydrogen Rebalance

This is a complete rebalance of the game's hydrogen and oxygen system.

Inspired by Thalyn's AHI Gas Rebalance mod: http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=842659131


Updated the calculations for the hydrogen engine. The intention here is to use the small hydrogen engine as a replacement for batteries in small ships, but not without large block hydrogen generation for the fuel. To that end the numbers for the engines are the following:

Small block hydrogen engine: 500 KW, 5.2 L/s (takes 2h and cca. 38k ice to fully charge a SB large battery)
Large block hydrogen engine: 5 MW, 39 L/s (takes 15m and cca. 28k ice to fully charge a SB large battery)

Hydrogen engines should be used in hydrogen powered ship IMO, because hydrogen thrusters don't require to much power and thus the hydro engine could provide the required power for the rest of the ship's systems. Using an example small ship with a mass of say 70 000 kg in 1g and a decent 6 m/s2 forward acceleration, one large tank would be enough for 30m for T0 or T1 thrusters. A second tank then would probably be more than enough for a hydro engine to power the rest of the systems on the ship.

Large block hydrogen generation is still net energy positive, but only by a little and is intended as a possible energy source in space where there is no wind power and the mining of ice would required some energy anyways.


Capacity and thruster efficiency changes have been refactored into scripts, so they now affect all gas tanks and hydrogen powered thrusters. The efficiency degradation and the power requirement calculations for modded thrusters are based on their tier rating, which is determined by comparing the thruster's force magnitude to its vanilla baseline counterpart.

Gas tank capcities are now calculated using the cylindrical volume of the block.

Technical Details:
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The reason I've put together this mod is the obvious imbalance SE has in its Hydrogen and Oxygen system. While the game has for example the correct energy density value for compressed hydrogen gas, it uses an incorrect formula to calculate fuel consumption for the thrusters. Probably in order to balance this, the capacity values for the hydrogen tanks have been increased to some ridiculous values. The thrusters also have too small power values, but I didn't want to change reactor output to match the realistic bigger values, so they remained smallish.

This system assumes that the hydrogen tanks store hydrogen in SLH2 (slush liquid hydrogen) form. This form has the highest hydrogen density, so tank capacity can correlate with the real volume the block occupies in space. The thrusters are assumed to work with SLH2/LOX fuel with a 4:1 oxidizer ratio. This is the same kind of fuel, the Space Shuttle Main Engines use (although those seem to use a 6:1 ratio). This hydrolox fuel has a 9.7 MJ/kg energy density and a density of 0.33 kg/L. This results in the fuel energy density value of 3.201 MJ/L that is set for the game.

Unfortunately realism stops here, because the theoretical maximum of the specific impulse for engines using hydrolox is around 530 seconds, which would mean big fuel consumption values. The values used for consumption together with the specified force magnitude values would require specific impulse values in 300-800 000 range, which would not be possible with these kind of engines. To achieve both high thrust and exhaust velocity, some kind of nuclear engine is needed, but that would be a different mod :)

Thruster specifications:
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The thrust-to-power ratio is set to 0.4 for all hydrogen thrusters. Fuel efficiency varies with the different tiers, higher tiers being less efficient (T0 and T1 is 0.55, T2 is 0.4, T3 is 0.3 and from T4 onwards it's 0.2)

Block | Size | Tier | Force | Consumption
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Large | Large | T0 | 7.200 MN | 10.2 L/s
Large | Small | T0 | 1.080 MN | 1.5 L/s

Small | Large | T0 | 480 KN | 0.7 L/s
Small | Small | T0 | 98 KN | 0.14 L/s

Capacity Changes:
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The capacities of the various gas containers have been adjusted to correlate with their volume. Oxygen is assumed to be stored at 300 bar, which is an approximately 240x compression. 1U for O2 in the game equals to the O2 in a 1m3 block. 1U for H2 is basically 1L (which in this mod means 1L of SLH2).

The new capacities are the following:

Small Block Small Hydrogen Tank: 700 L
Small Block Large Hydrogen Tank: 12 200 L
Large Block Small Hydrogen Tank: 24 500 L
Large Block Large Hydrogen Tank: 331 000 L

Small Block Oxygen Tank: 600 U
Large Block Oxygen Tank: 6 000 U

Large Block Cockpit: 9 U O2
Small Block Cockpit: 1 U O2
Fighter Cockpit: 4 U O2

Hydrogen Bottle: 8L (inventory size: 10L, mass: 2kg)
Oxygen Bottle: 8U (inventory size: 8L, mass: 16 kg)

Suit Hydrogen Capacity: 2 L
Suit Oxygen Capacity: 6 U

Breathing rate has been reduced to 0.0034 U/s

Oxygen and Hydrogen generation:
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Ice has its real 1.091 L/kg density and yields 3U oxygen and 1.3 L Hydrogen. The calculation here again assumes SLH2 and compressed oxygen generation. This means that the 0.11 kg hydrogen (2/18) with a density of 0.085 kg/L results in 1.3 L SLH2 and the 0.89 kg oxygen with a 1.428 g/L density results in 623 L O2, or 1.5 U when compressed.

Normally the electrolysis of H2O would need around 290 KJ of energy per mol, so 1 kg of ice (55 mol) would need 16 MJ. If the O2/H2 generator just processed 1 Kg of ice per second it would need 16MW of electrical power. That's a bit too much from a game perspective, so the calculations use 290 J instead.

Here are the changes for the oxygen generators:

Large grid oxygen generator: consumes 5 kg/s ice, producing 7.5 U/s O2, 6.5 L/s H2, while consuming min. 10W and max. 800 KW
Small grid oxygen generator: consumes 1 kg/s ice, producing 1.5 U/s O2, 0.13 L/s H2, while consuming min. 10W and max. 160 KW

Oxygen Farm has been adjusted to keep the original ratio to the oxygen generator.