Extraterrestrial Energy – Moon or Sun Power

The search for viable forms of clean alternative energy continues as each potential solution carries with it significant shortcomings:

• Nuclear power presents environmental challenges, in the disposition of high and low level radioactive waste or in the event of a nuclear accident (e.g. Chernobyl),
• The sun can be impacted by the presence of clouds,
• Winds are inconsistent or intermittent, and
• Hydro power dams are viewed as disruptive to the environment.

Nuclear Fusion – Energy From the Moon

Research in alternative energy sources continues, either to address the apparent shortcomings of the aforementioned energy sources or to discover new extraterrestrial sources. One such source is helium-3, originating from the moon, which would combine nuclei to produce energy. This process, termed nuclear fusion, has already been tested with hydrogen isotopes deuterium and tritium, but with challenges regarding safety and production.

Helium-3 appears to be safe in that it does not emit any pollution or radioactive waste. With respect to potential, just over 2 pounds combined with 1.5 pounds of deuterium produces almost 20MW-years of energy; alternatively, 25 tons of helium-3 would provide enough power to sustain the U.S. for one year.

To capture 25 tons of helium-3 will require more exploration of the moon. Lunar rock is estimated to contain more that 1 million tons of the element, 10 times the amount of energy found in all fossil fuels or $4 billion a ton in energy equivalence of oil.

In order to operationalize this potential solution, there are two primary issues to address:

• Extraction and refinement of helium-3 from the lunar surface, particularly considering its low concentration in the soil, and
• Fine tuning of the fusion process, particularly in achieving sustainably high enough temperatures to actually produce electricity.

Solar Panels in Space

The sun may still present the most promising space-based source of fuel, but perhaps by harnessing it beyond the stratosphere where we avoid the large and inefficient footprints of solar panels. Termed space solar power (SSP), this approach removes obstacles like rain, clouds and darkness and is immune to seasonal fluctuations. As currently conceived, SSP attaches solar panels to orbiting satellites or the moon, and the electricity created is converted into microwaves which in turn, are received on the earth through rectifying antennas. In essence, the process is quite similar to the use of satellites in transmitting cell phone conversations, to the point where the current infrastructure of communication satellites pose a potential platform for this approach.

The challenge lies in the economics. Initial studies envisioned stationary 18 square mile solar panel arrays transmitting microwaves to similarly sized rectifying antennas; which though impressive in the amount of energy produced (one such station would generate twice the energy of the Hoover Dam), proved extremely costly. More recently, the use of smaller satellites, less than 1,000 feet in length, orbiting at 300 miles above the Earth are being evaluated, each with the potential to power 1,000 homes. But, challenges, primarily economic remain:

• Launching, initializing and maintaining “solar farms” on the moon is both capital and manpower intensive.
• Launching a satellite remains expensive, over 1,000 times more than transporting an object across the U.S. via airplane.

The key to making this work will be the development of reusable launch vehicles and further analyses to determine the break even point in terms of energy used to send a satellite into orbit.

In considering these options one cannot help but surmise that the solution to mitigating the exhaustion of Earth’s natural resources may well be in space.