| POWER SYSTEMS David A. Dietzler, 2007 The first things to land on the Moon are solar panels, wiring, and robots to deploy those systems. In addition to solar panels, etc. fuel cells, water electrolysis cells, piping, pumps, water storage tanks, insulated LOX storage tanks, space radiators shielded from the Sun and hydrogen storage tanks that are likely to use room temperature hydride storage in FeTi alloy powder or carbon nanotubes rather than cyrogenics. A small short duration two man team might be needed to assist the robots for this mission. Once solar panels and nightspan power storage systems are in place it will be possible to land inflatable torus or tire shaped habitat modules that will be covered up with regolith by the robots. The first human crews can them go to work on the Moon. It seems reasonable to me that a small nuclear reactor could be included in this for nightime power. If we don't have nuclear power in space we might have lots more nuclear fission on Earth because SPS construction and helium 3 mining might never succeed. The SP 100 reactor deployed in 1992 generated 2000 kWt and 100 kWe and amassed 5422 kg.. The SAFE 400 reactor that might be deployed soon would make 400 kwt and 100 kWe and amass only 1020 kg.(1) If public fears of space reactors stifle space industrialists, perhaps the reactors can be launched from far out at sea on a floating platform. The advantage of having a reactor is that if fuel cell systems fail the reactor provides back up and it reduces the amount of power that must be stored for nightspan thereby reducing the mass of nightspan storage systems. I do not favor the south polar area for a Moon base or the so called "peaks of eternal light" that they are not. The Ocean of Storms is much better as it allows access to iron and titanium rich mare. Just west of the Aristarchus plateau in the Ocean of Storms is the largest deposit of volcanic glass on the Moon with an area of 37,400 square kilometers that could serve as a source of oxygen, chlorine, zinc, gallium, sulfur and other elements. (see: http://astrogeology.usgs.gov/Projects/LunarPyroclasticVolcanism/lunpyroWebDb.html and http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/DOCS/EIC048.HTML ) Oxygen can be extracted from FeO in pyroclastic glass by heating to 900-1100 C. with hydrogen. The Ocean of Storms KREEP Terrain is one of the biggest and could serve as a source of fluorine and chlorine as well as potassium, phosphorus and rare earth elements. The nearby Marius Hills boasts over 200 low volcanic domes. Beneath this area there might be intact chambers of volcanic gas rich in CO and H2S and even Cl. Chlorine is needed for CaCl2 electrolyte in FFC cells for Ti production. Fluorine is need to make CaF2, AlF3 and LiF flux for aluminum and calcium electrolysis by the EMEC process. About 30% of mare regolith is anorthite, a source of Al and Ca. Iron and titanium have obivious uses, and CO gas could be used to smelt iron and steel. The mare are much easier to mine than the rugged terrain of the south polar region. With a small reactor that is re-entry safe and fuel cell systems nightspan will be survivable. Eventually, 10 MWe (at least) power towers will be built 700 miles to the west and east of the lunar industrial base to supply three phase AC power. If the voltage is high enough, we can transmit power that far. Additionally, our cables will be largely calcium, a better conductor than copper and far better than aluminum that is used for long distance power transmission cables on Earth. These towers will consist of sectional steel rods supporting a convex titanium dioxide reflector that bounces light from polished sheet metal reflectors (heliostats), possibly magnesium, surrounding the tower down to a black boiler filled with salt. The molten salt will go to a steam generator to turn three phase AC generators made on the Moon by casting, drop forging, etc. We might have to build the tower on its side and hoist it up with cranes. Every reflector will need a small electric motor system to keep it oriented and wires to power sources and electronic controls that provide guidance. Hundreds of small motors will be necessary and the parts for the tracking systems and mounts will be numerous also. Perhaps we can drop forge rotors and stators the way we can drop forge sprockets. We will have to extrude large amounts of aluminum and calcium or Al-Ca-Si alloy wires to make heavy power cables 700 miles in length. We will extrude fibers of Ca and interlace them with fibers of Al for support. Aluminum cladding might be necessary to prevent sublimation of the Ca fibers. Shorter lengths will be spliced together to make 700 mile lengths. This will be one of the biggest jobs next to building a mass driver and it will be our first huge project after building metal smelting furnaces and getting metals production going. We will need large high voltage transformers. These will be made by casting huge iron molds and pouring FeSi from magma units and covering them with iron plates to prevent evaporation. These transformers might not be the best but they might be the best we can do. The transformers will sit on iron plates mounted on huge cast basalt heat sinks and they will have foil solar shielding. Helium or CO2 gas cooling and space radiators might also be supplied. The same pump and radiator designs used for fuel cell reactant storage systems might be used. Since a good ground will be impossible in the dry regolith there will have to be cables back to the generators like a closed circuit DC system. The cables will be mounted on steel poles only ten or fifteen feet high. There will be no storms or high winds or people who might touch the cables. The cables will not short out to the dry ground. So we probably won't need high voltage circuit breakers. Insulators will be made of glass and many small parts will be manufactured by humans and CNC machines. Large capacitors and coils to deal with reactance in the lines when industrial motors are churning at the base will be necessary too. The only things that might effect the system are solar flares and the magneto-tail of the Earth. So more planning must be done. With 24,000 tons of blister steel in ten or eleven years' time, certainly we can build such a power system and even get to work on a huge mass driver, presuming we can make enough Al or Al alloys for the coils and high power electronics. Will we make massive transistors and diodes or big vacuum tubes with the aid of the free vacuum? Then we will need tungsten or tantalum not available on the Moon, unlike silicon that we will dope with Al for p-type material and phosphorus from KREEP for n-type material. Meanwhile, we must build fleets of robotic miners, metal modules for living and working, more machine tools, and many other things. Llaminated transformer cores might be from slabs of FeSi with layers of glass in between that we will produce plenty of. We will also have to build turbines with cobalt steel blades, preferably stainless, and that means we need chromium. And we will have to build large AC generators. We will not wait for the steel to pile up but use it as we produce it. With three Eiffel Towers worth of steel in 10 or 11 years, we can do many things. We will also need DC power for electrolysis. This could come from solar panels by day. In the later and early parts of night span when we rely on the distant power towers we will have to rectify AC to DC and this will require some big diodes! Or would we just let an AC motor turn a DC generator? Some may argue that we should do most smelting at the L5 shack, but how are we going to build massive ceramic and cast/sintered basalt block furnaces there? And how are we going to get hundreds of mining machines on the Moon to dig up tens of million tons of regolith every year without building them on the Moon after spinning up industry there? We will need 1,000 Mark 3 miners just to get 33 tons of helium 3, about enough to power the USA for a year. And what's wrong with developing the Moon for the sake of the Moon? 1) Nuclear Reactors for Space, World Nuclear Assoc. http://www.world-nuclear.org/info/inf82.html |
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| I could draw this better with a ruler, T square and protractor. A vertical line, a radius, an equal opposing angle, and the reflector at right angles to the line bisecting the angle between the Sun and the line from the convex reflector are what one needs to think about. |
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| Power tower plus heliostats can direct solar rays vertically or focus them to a point. |
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| An inverted paraboloid reflector. |
| spherical reflector |