| I've been anticipating all kind of questions, like,"How do we ever get something so big (like a blast furnace) up there?" See the page about oxygen extraction methods. The 70 tons magma unit using 3.5 MWe has a thru put of 5000 tons per year. 43% oxygen. So with iron and silicon coming out and oxygen we'd have about 2500 tons of ceramic blocks per year. With a 7 ton 350 kWe magma unit we'd have about 250 tons of ceramic blocks every year. We could make a nice little set up with that to get started! We could weld the blocks together and seal the inside of the furnace to make it gas tight with a subterrene molybdenum heat probe sort of device. Or we could ladle molten magma from the electrolysis units over the bricks/blocks and be very careful. Get it? We make 95% of everything on the Moon with lunar materials. |
| More Information 2 |
| Recycling CO2, CO, O2 I) Direct CO2 electrolysis to recover O2 and CO. Doesn't require H2 but requires a lot of energy (up to 5x as much as H2O electrolysis) and expensive Zr-Y-Pt cells that must be shipped to the Moon. The main question to answer: How much energy does it take per unit of CO2 mass electrolyzed? II) CO2+H2 (with Fe-Cr cat @ 400 C.) ===> CO + H2O H2O electro. to H2 + O requires less energy than CO2 electrolysis and an Fe-Cr cat that could be make on Moon. But it requires hydrogen, although the H2 is recycled. And we recover Oxygen. III) CO2 + C @ 900 C. (off gas temps.) ==>CO + CO Simple, no electricity use, no hydrogen use, but it requires solid carbon that will be used up to form CO. Electricity will be used to make more oxygen from magma electrolysis, but this is done anyway to keep producing iron and silicon supplies. Also, to get more carbon, we need to mine volatiles, cometary ice at poles, and even tap chambers of trapped volcanic gas. To get carbon from CO, CO2 and CH4 we just have to pyrolize (decompose with heat) CH4 at only 900 C. to get carbon and hydrogen. CO2 can be combined with H2 to make CH4 and H2O also. 3CO2+6H2=CH4+2CO+4H2O The H2 must come from water electrolysis. We do get oxygen when we electrolyze the water. So this is no free lunch, unless Thomas Gold is correct and vast coal like mineable carbon deposits exist in the Moon. Or, we can come up with enough CH4 from regolith, ice and volcanic chambers to keep making carbon. The CO2 will simply be reacted with the C to make more CO, but how much CO do we need? This is not a closed loop system like A and B. Conclusion: Unless we have vast carbon supplies and want to keep expanding production, (III) just looks like a good way to make some CO from CO2 and (II) looks like the best closed loop recycling system unless direct CO2 electrolysis becomes so efficient through technological advancement that it becomes worth it to import the equipment. |
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| Reverse Water Gas Shift Reactor |
| The smallest amount of energy needed to electrolyze one mol of water is 65.3 watt hours at 25 C. When the hydrogen and oxygen burn 79.3 watt hours are released with the extra 14 watt hours coming from heat absorbed from the surroundings during electrolysis. High temperature electrolysis requires less electricity because the water absorbs some heat into the splitting process. High temperature electrolysis can allow a 30% reduction in electrical energy input. On the Moon we might apply solar energy to reduce electricity requirements for electrolysis of water. if 100 tons of iron is smelted: Fe2Si2O6 (264) + 2CO (2*28) ===> 2Fe (2*56) + 2SiO2 (2*60) + 2CO2 (2*44) 235.7 tons ferrosilite + 50 tons CO ===> 100 tons iron + 107 tons silica + 78.6 tons CO2 H2 + CO2 ===> H2O + CO 78.6 tons CO2 + 3.57 tons hydrogen ===> 32 tons water + 50 tons CO 32 tons water = 1,777,777.8 mols (1,777,777.8 mols)(65.3 watt hours/mol) = 116 megawatt hours! |