Energy from the Moon


There may be an opportunity for lunar resources to play a role in the energy industry here on Earth. Power generation is a vast and growing market. Energy is a product that may legitimately be worth bringing back to the Earth's surface from the Moon.

How will we do this? In 1989, a NASA report concluded that, for the energy needs of the next century, we need to consider two alternatives enabled by a lunar outpost: solar energy collected on the lunar surface and beamed back to Earth via microwaves, and the return to Earth of a light isotope of helium, He-3. Both of these options would largely avoid the biggest problems of energy generation here on Earth: pollution, acid rain, ozone generation, carbon dioxide production with its potential for global warming, and large operations with highly radioactive fuels.


Helium-3

Along with the other light gases mentioned above, we can extract an isotope of helium from the regolith. He-3 has the potential to be used in fusion reactors here on Earth to provide electrical power. This technology, while still in the research stage, promises to be much "cleaner" than current,fission-based plants which consume uranium, and even cleaner than those fusion plants currently under development which would use radioactive tritium as a fuel. Why would we go to the moon for this material?
Along with deuterium, which can be extracted from sea water, He-3 is the primary fuel of a clean nuclear fusion reactor currently being investigated by U.S., European, and Japanese fusion research scientists. Some of these scientists believe that a demonstration fusion power reactor using the He-3/deuterium reaction can be built within 10 or 15 years and a commercial power reactor within 20 years. It would generate only a very slight amount of radioactivity, equivalent in nature to that produced by hospitals in their nuclear medicine areas. When used in this plant, He-3 would have so much energy that it would require only 20 tons-less than one Shuttle load-to supply all the electricity used in the United States in a year. The current cost of fuel used to provide this electricity is tens of billions of dollars-and going up. We can estimate that the single Shuttle-load of He-3 might be worth about this same amount-or more when the environmental impact of fossil fuels is included.

Long-range strategies to use the Moon to produce Helium-3 call for large mobile miners, such as this one designed by the university of Wisconsin. This program would need to be preceded by smaller efforts such as schematized below to learn more about the chemistry and operation of such light gas recovery plant.
Of course, this story depends on the successful demonstration that the He-3 reactor will work. It also depends on whether we can economically extract He-3 from the Moon and bring it back. But many believe that both the successful reactor and the economic recovery of He-3 are likely events in the early 21st century. NASA is not a part of this fusion research, but the capability of recovering light gases implanted by the solar wind, if developed for smaller scale propellant or life support programs, can act as a "proof of concept" technology program to support future decisions made by the Department of Energy. The biggest hurdle is likely to be the extremely large mining requirement. Since He-3 comprises only 1 part in 2-3000 of the total helium, and since the total helium level is only 10 to 200 ppm, tens of millions of kilograms of regolith must be mined to obtain one kilogram of He-3. Of course, its value will be similarly large.

In addition to helium, the extraction of hydrogen, methane, nitrogen, and oxides of carbon would be possible using this technology. Thus, lunar-derived fuel for spacecraft and life support materials are potential coproducts.

Complex products-Can we make solar cells?

The other option for returning power to Earth, collecting solar energy on the lunar surface and beaming it back to collectors on the Earth, requires a somewhat different capability at the outpost. In this proposal, large arrays of solar cells would be manufactured and emplaced on the Moon. The energy they collect would be converted into microwaves and transmitted to Earth using large antennae, which would also be produced on the Moon from indigenous materials. Previous studies have shown that it is not feasible to launch all of the material required for such a project from Earth.

We must ask whether we can make all the necessary items for such a large project from the resources available on the Moon. The products required include solar cells, wires, microwave reflectors, and metal, glass, or ceramic support structures. We have already demonstrated in the laboratory the ability to make pure silicon for solar cell manufacture, iron for structures and wires, fiberglass and iron for reflectors, and a variety of other individual products from simulated lunar materials. The vacuum and lower gravity present on the Moon may actually make it easier to produce many of the articles we need. It remains to be shown in a research and development program that large scale production of these materials and fabrication of such items can actually be carried out on the Moon, but a focused effort should accomplish many, if not all, of these goals. This "Lunar Power System" would then become largely an engineering program. The most "high tech" elements of this system would most likely still be imported from Earth, however.

After the development phase is complete, both of these enterprises could actually be run at a profit. The market for energy here on Earth will steadily increase as far into the future as we can see. Even if energy conservation programs are successful, the growing population of Earth and the increasing per capita use of energy, especially in developing countries, demand that we consider future energy needs in our lunar plans. The benefits to Earth's environment alone make these technologies worth exploring. We should remember that similar technology shifts in the past, such as the move from burning wood or coal to the use of petroleum products, took decades to evolve- this could be the next step to a benign energy source for an expanding population.

Shown here is an array of solar collectors envisioned as part of a Lunar Solar Power System. This field would collect the energy from sunlight and convert it into electricity. This power would then be converted into microwave beams directed toward the Earth. Large rectennas on the Earth would collect this energy and direct it into existing and new distribution grids. There are many technologies and capabilities which need to mature before such an effort can be successful, hut the development of scientific principles has already begun.