[Spaceships] Reasonable numbers for Refinery Systems / 'Artificial' Fuel?

[vicky_molokh]

Greetings, all!

Okay, the official refinery rates are weird, producing (at SM+5) a half-tonne of rocket fuel per hour, which is way more than is required to run the refinery using same fuel.

But! While this used to be a fuzzy area, I'm planning to officially declare that my setting has a common practice of synthesising a fuel from ubiquitous components when there's abundant energy.

Perhaps the simplest way to make sure it doesn't run out of control is to see how much energy can be gained from the given amount of fuel, and declare that it takes twice as much energy to synthesise it. That means that if a fuel cell (1 Power Point) can work for 24 hours on a tank of fuel, then it takes 2 Power Points to produce one fuel tank of said fuel (over same duration; 1 PP if working over 48 hours etc.). But perhaps there is some reason these numbers don't make sense.

My intent is to make sure that fuels are an option, not a must-have, when pitted against batteries. (TL6+3^ batteries; can provide up to 2 Power Points over up to 6 hours, and can recharge from any power source, with no spontaneous discharge, no risk of explosion, and ability to be safely recharged thousands of times at the very least.)
At those numbers, IMO, fuel-powered (motorised) yachts still make more economic sense than battery-powered ones (because you need more endurance), but ornithopters and semi-reactionless* (0.5G per PP) aircraft can easily get by on batteries, since those are easy to recharge and rarely, if ever, need to stay in the air for more than 6 hours at a time.

So, cost of fuel seems like a prime balancing factor. Making fuel requires a refinery module, a power source, access to raw materials (cheap, you still need to have them right here now), and of course a place to store fuel and refuel the clients. Logistically, fuelwork seems pretty complicated compared to essentially reselling electricity.
So, what are reasonable price ranges for a fuel that is synthesised from ubiquitous components in a manner described above? How are they likely to compare to prices of raw power?

Another issue is the balance of jets against MPDs. But since a single fueltank is enough for 1 hour of jet flight, while a single battery can power two MPDs for 3 hours, things seem okay. (Jets are still better in terms of maximum acceleration per unit mass.)

Thanks in advance!

* == Mono-Polarised Displacer. Essentially, a more expensive variant of a unidirectional magnetic planetary drive, but with no side effects whatsoever. Also works in space, somewhat.

[Langy]

Why do you need to have the fuel use up more energy during synthesis than it produces? Even some energy-intensive processes, like thermal depolymerization (which turns biomatter into oil), are a net producer of energy (and are typically powered by the same stuff they create). The reason it doesn't violate any laws of thermodynamics is that using that fuel doesn't produce products that can then be re-ran through the system again.

[vicky_molokh]

Originally Posted by Langy

Why do you need to have the fuel use up more energy during synthesis than it produces? Even some energy-intensive processes, like thermal depolymerization (which turns biomatter into oil), are a net producer of energy (and are typically powered by the same stuff they create). The reason it doesn't violate any laws of thermodynamics is that using that fuel doesn't produce products that can then be re-ran through the system again.

I'm assuming that a there's some waste of energy in the process.

O2 + 2×H2 -> 2×H2O + energy
energy + 2×H2O -> 2×H2 + O2

Isn't it?

(Note that I am postulating the use of inert, ubiquitous components, not something that already stores a significant amount of chemical energy. A typical space-operatic example would be mining ice asteroids and turning them into rocket fuel.)

[cccwebs]

The problem isn't in how much per hour is processed, but in how much is actually produced (the ratio of end product vs raw materials). The rate for processing is for the raw material and doesn't mean that you have that same amount of usable fuel after processing.

Consider the Titanic Gas Mining Platform in Spaceships 6. At TL 10, it processes 30,000 tons of atmosphere per hour to result with 5.5 tons of fuel per day. That's 6 refineries (+13 SM) processing enough fuel in one day to fill one +6 SM fuel tank (with a half a ton excess). A +13 SM MHD Turbine (TL 10) would provide 2 PP energy with an internal tank size of 5000 tons and run for 12 hours. The refinery would not be able to process enough fuel to sustain its own operations. It's a good thing the Titan uses fusion reactors to provide energy.

[Ulzgoroth]

Hasn't it been said that the stats for chemical power plants are unrealistically good in order to make them useful?

Originally Posted by cccwebs

The problem isn't in how much per hour is processed, but in how much is actually produced (the ratio of end product vs raw materials). The rate for processing is for the raw material and doesn't mean that you have that same amount of usable fuel after processing.

Consider the Titanic Gas Mining Platform in Spaceships 6. At TL 10, it processes 30,000 tons of atmosphere per hour to result with 5.5 tons of fuel per day. That's 6 refineries (+13 SM) processing enough fuel in one day to fill one +6 SM fuel tank (with a half a ton excess). A +13 SM MHD Turbine (TL 10) would provide 2 PP energy with an internal tank size of 5000 tons and run for 12 hours. The refinery would not be able to process enough fuel to sustain its own operations. It's a good thing the Titan uses fusion reactors to provide energy.

Makes no sense when your refinery is, for instance, electrolyzing water. Not all 'refining' is extracting a trace component.

[vierasmarius]

Originally Posted by Ulzgoroth

Makes no sense when your refinery is, for instance, electrolyzing water. Not all 'refining' is extracting a trace component.

I think this is the core question. Is the refinery taking complex, energy-rich hydrocarbons and processing them into a usable form? Or is it doing the more energy-intensive task of extracting Hydrogen from more complex molecules? The former requires specific chemical inputs that won't be available on all worlds, the latter consumes more energy than it produces. Spaceship's description of the Refinery implies the latter, but the stats it gives indicate the former.

[Ulzgoroth]

Originally Posted by vierasmarius

I think this is the core question. Is the refinery taking complex, energy-rich hydrocarbons and processing them into a usable form? Or is it doing the more energy-intensive task of extracting Hydrogen from more complex molecules? The former requires specific chemical inputs that won't be available on all worlds, the latter consumes more energy than it produces. Spaceship's description of the Refinery implies the latter, but the stats it gives indicate the former.

It's not a question, the answer is that the Refinery section covers both of those and a number of other material-processing roles besides.

Giving all those things the same stats may be not entirely appropriate, of course.

[Anthony]

Generally speaking, a refinery that works on cheap, common input should produce a relatively fixed number of $/hr, not any particular volume, because the cost of fuel is basically (cost of raw materials) + (cost to refine the raw materials) + (cost to transport the raw materials or finished fuel). This doesn't work very well where your input material is high value or very unevenly distributed, since the first and third terms become substantial at that point, but it's good for things you can get by refining water.

In the end, a refinery is just a special case of a factory.

[Sunrunners_Fire]

Originally Posted by Anthony

Generally speaking, a refinery that works on cheap, common input should produce a relatively fixed number of $/hr, not any particular volume, because the cost of fuel is basically (cost of raw materials) + (cost to refine the raw materials) + (cost to transport the raw materials or finished fuel). This doesn't work very well where your input material is high value or very unevenly distributed, since the first and third terms become substantial at that point, but it's good for things you can get by refining water.

In the end, a refinery is just a special case of a factory.

Raw Materials: Water costs, ah ... Spaceships says it costs G$20 per ton.

Refine Costs: (power plant module + refinery module) * 1.5 (upkeep, maintenance, staffing and operation assumption; feel free to adjust) / 50 (years) / 365 (days) / (24 hours) = cost to refine per hour.
Assuming a TL9 fusion reactor module from Spaceships 1.

Transport Costs: Um ...

Total:
10 + (330k * 1.5 / 50 / 365 / 24) + X = G$1.13 per 0.5 tons of fuel, plus transportation costs.

However, this assumes it is producing "rocket fuel (liquid hydrogen / oxygen)", which Spaceships prices at G$800 per ton. That is quite a bit of transportation cost! Heh. (G$398.87 per half-ton.)

[Anthony]

Originally Posted by Sunrunners_Fire

However, this assumes it is producing "rocket fuel (liquid hydrogen / oxygen)", which Spaceships prices at G$800 per ton. That is quite a bit of transportation cost! Heh. (G$398.87 per half-ton.)

This is called 'spaceships economics is broken'. Which isn't really news. Though I would divide by 10 years, not 50.