Re: [Spaceships] Antimatter Factory
 

Okay, I only naively compared fabrication/production rates to the facility's construction cost. Let's see what else there might be.

GURPS Spaceships 2 has some sections on operating costs, though they are mainly geared at traveling spaceships rather than installations. Operating expenses for an industrial facility might include:

• Bank Payments (p. SS2:29) -- SIGNIFICANT. If you paid for construction with a loan then your final cost will be higher (because of interest) and it will thus take longer to break even. The "quick-and-dirty" interest calculations on p. SS2:27 mean your final cost will be 144% of the basic cost (1 to 2% of the facility's cost per month, for 12 or 6 years respectively).
• Crew Salaries (p. SS2:29) -- NOT SIGNIFICANT. I'm not sure how factory workers work with GURPS Spaceships. Can a non-automated factory (such as a Fabricator) be run by someone in a Control Room control station, or does it require additional actual bodies in the factory? If the latter, how many machinists are required to operate, say, an SM+15 factory at full capacity? The Work Shack and Space Industrial Park both mention construction and factory workers (p. SS6:7-8), who are in addition to the crew needed to run the ships; the Space Factory and Class III and Class IV Orbital Spaceports only mention technicians (who are already required to maintain the systems); and the Class V Spaceport mentions that its technicians double as factory workers when needed (is that when additional workers are needed, or when any workers are needed?). Despite the questions above, even if all the occupants of the entire ship are being paid to work in the factory, crew salary won't be a significant expense compared to the fabrication rate. At TL9, most crew will earn $3,600 per month (p. SS2:30) or $20.45/hr at 22 days/month, 8 hours/day. If a Class V Orbital Spaceport employed all of its potential 31,000 occupants, at $698K/hr (90% workers at $20.45K/hr, 10% supervisors at $40.91/hr), that would be only 0.5% of the factory's production capacity ($150M/hr). If we assume a factory requires as many workers as workspaces, then it's only $6.7K/hr.
• Consumables (Fuel and Provisions, p. SS2:30) -- NOT SIGNIFICANT. If the factory is powered by a fueled power plant, you'll have to pay for more fuel on some regular basis. Unless you're running a chemical power plant, this is unlikely to be a significant expense compared to fabrication rate. Anyway, all of the factories use Solar Panel Arrays.
• Repair and Maintenance (p. SS2:31) -- NOT SIGNIFICANT. The rules for maintenance in the Basic Set (p. B485) produce maintenance costs greater than GURPS Spaceships 2 lists for cheap or very cheap ships (pp. SS2:27-28), so I'm going to assume those aren't the correct rules to use and that there are no maintenance costs for a spaceship in good condition.
• Taxes (p. SS2:32) -- SIGNIFICANT. Taxes are 10% of profits for most businesses, 5% for government-subsidized businesses.
• Insurance (p. SS2:32) -- MODERATELY SIGNIFICANT. Hull and Machinery Insurance is 0.1% of the ship's cost per month, doubled if it has volatile systems (and I realize now that an Antimatter Factory should be considered a volatile system -- I'll add a mention of that above).

So a Class V Orbital Spaceport (p. SS6:10) costs $180.32B and its factory has a production capacity of $150M/hr (minus 40% input cost). It can generate a gross profit of $64.8B/month worth of small items ($/hr rate), +$2.7B/month on its in-factory production lines ($/day rate), or less than $270M/month assembling ships off of the production line ($/day rate, ×1/10). With a 2%/month loan payment, the spaceport runs in the red for the first 6 years ($2.7B - $3.6B loans - $1.2M salaries - $270M taxes - $180M insurance = -$1.36B per month), but makes $2.25B/month after that (16.6%/year ROI), breaking even in its tenth year. With a 1%/month loan payment, the spaceport makes a profit from year one: $445M/month for the first 12 years, $2.25B/month after that. If the spaceport is financed in-house (no loan payments), then it simply takes 6.7 years to break even. Once the spaceport has paid off its loan (or construction cost) it can choose to make only $61.5M/month profit (1/36th of in-factory profit) assembling ships off of the production line (0.41%/year ROI).

The Antimatter Production Facility can make a $106M/month profit for the first 6 years with a 2%/month loan payment (31%/year ROI) or $147M/month for 12 years with a 1%/month loan payment (43%/year ROI), then $189M/month after that (55%/year ROI). Financed in-house, it takes 1.8 years to break even. Those ROIs do seem high. Dividing antimatter production rates by 2 or 3 produces ROIs more in line with the spaceport, but maybe high ROIs are not inappropriate for a facility composed 25% of volatile systems which might cause the whole thing to explode!

Re: [Spaceships] Antimatter Factory
 

I found this post to be super-helpful!! Thanks munin!!

I included it in my ship designs and formatted your post nicely into a sheet.

This is so wonderful.

Re: [Spaceships] Antimatter Factory
 

I think that an Antimatter Factory should just be a specialized version of Factory that produces a value of antimatter equal to the value of the products of a standard Factory. The difference should be that an Antimatter Factory should require two Power Points and should be a volatile system.

Re: [Spaceships] Antimatter Factory
 

Interesting. That would more than double the output!

I made an optional rule for my setting that TL10 AMFs produce 10x the output. This allows the creation of anti-matter boosted H2 in a time period I thought was reasonable (1000 hours to create 50K tons of ambH2, or about 42 days). So, the ship I created could continually refine and boost H2 with the on-board factories/mining/refinery and provide on going fuel for the attached explorer craft and various small worker/miners.

It's all somewhat superscience, so I don't feel TOO guilty tossing in this one ^ tech in my otherwise "realistic" TL10 setting. :D

I am having a blast making these Spaceships with the GURPS spaceships system. Just the perfect amount of detail and customization. I would really love to see another 50+ page book in the series with TONS (pun intended!) of design options. I'm like having 13-year-old-me giddy fun with this.

Re: [Spaceships] Antimatter Factory
 

If we look to this thread from a few years ago, we find a very reasonable estimate of Power Points as 1PP = 50kW per ton of ship.

This puts an absolute upper bound on antimatter production of 50kW * 1 day / c^2 = 48 micrograms per day per ton of ship mass for a system drawing one Power Point. That's about $1,000 of antimatter per day at Spaceships prices.

Of course, that absolute upper bound means 100% efficient conversion of energy into antimatter, which is probably a ludicrous idea! As far as we currently understand these things, matter and antimatter must be created in equal amounts, which automatically halves our efficiency — 24 µg/day/PP/ton.

As stated earlier, Spaceships AM costs match the TL11 figures from the Designer's Notes, which pin that to a factory producing 100,000 µg/day for an installation cost of $1B and a production value of $100,000/hour. A hundred thousand micrograms per day suggests a single system on board a 2,000-ton ship at that impossible 100% efficiency. The only slightly less-impossible 50% efficiency would mean a single system on a 4,000-ton ship, which matches up exactly with the table in the original post.

I would suggest 20% efficiency, meaning 10,000 tons or a SM+10 ship, as a very reasonable non-superscience TL11 figure. That would mean a table like this would fairly closely match the figures in the Designer's Notes, assuming the efficiency scales roughly with the cost at each TL:

At TL9, divide production by 100 and multiply cost by 25.
At TL10, divide production by 10 and multiply cost by 5.
At TL11, use the listed figures.
At TL12, double production and divide cost by 20.

Alternatively for TL12, multiply production by 10 and divide cost by 5, but a non-superscience system requires 5 PP!

Re: [Spaceships] Antimatter Factory
 

I derive PP from the Weapon Battery Outputs. If we assume that effective laser weapons have a 50% efficiency (otherwise the waste heat would broil the occupants of the spacecraft), then a SM+10 Major Battery would require 300 MW of energy (2 × (3 GJ/20 seconds)). The end result would be around 30 kW per metric ton of spacecraft (I just convert tons 1:1 to metric tons because there is no way that any reasonable spacefaring civilization will not use metric units).

Since antimatter production has a realistic maximum efficiency of 50% (half of the energy produces antimatter and half the energy produces matter), the maximum amount of energy for realistic production would be 30 kW per metric ton (assuming 2 PP). With 90 TJ required per gram of antimatter (E=mc^2), the maximum possible realistic production would be 12 micrograms per hour per metric ton of spacecraft (120 milligrams per hour for an SM+10 spacecraft). From the cost of antimatter given in Ultratech, we can calculate maximum efficiency, meaning that a TL12 civilization produces antimatter at a 41.67% efficiecy, TL11 8.33%, TL 10 0.0833%, and TL9 0.00833%. An SM+10 factory would produce 100 milligrams per hour at TL12, 20 milligrams per hour at TL11, 200 micrograms per hour at TL10, and 20 micrograms per hour at TL9.

Re: [Spaceships] Antimatter Factory
 

This is awesome. So now I ask you gents to help me tune up my implementation.

Goal: to have factory facilities on board my space station/craft that serves as a base of operations for long-term exploration missions.

My setting is TL10.

The factory is in a SM+15 ship.

I have two anti-matter plasma torch engines with two fuel tanks (150K of fuel).

Based on your suggestions (aka "how you would do it"), how long would it take to make 150K tons of anti-matter boosted H2?

Would that take about 300K tons of ice (comets, asteroids, etc.)? More?

I appreciate your thoughts!!

Re: [Spaceships] Antimatter Factory
 

Antimatter-boosted hydrogen uses grams of antimatter per ton of hydrogen. So 150K tons of fuel needs 0.15 tons of antimatter.

Celti's table says 400 µg per hour at TL10, so that's roughly 43 thousand years.

Re: [Spaceships] Antimatter Factory
 

Much more. Ice is roughly eight parts oxygen to one part hydrogen by weight. Call it 1.5 million tons of ice in round figures. However, that's only a block 100 x 100 x 150 metres, which is a fairly small comet.

Re: [Spaceships] Antimatter Factory
 

The problem with antimatter-boosted hydrogen is that its price in Spacecraft is 0.1% of the TL 10 price of the requisite antimatter in Ultra-Tech, so it should cost $12 billion per metric ton at TL10 rather than $12 million per metric ton presented in Spacecraft. It would have to use milligrams of antimatter per ton for the price given in Spacecraft to be economically correct at TL10.