People have been searching for clean alternative energy sources for decades to no avail. As soon as one source seems to pass the test, someone uncovers its fatal flaw.Nuclear,wind, solar and hydropower have all been dragged through the mud to some degree. Traditional nuclear fission is too risky, winds aren't consistent, thesundoesn't always penetrate thecloudsandhydropowerdams disrupt natural environments.
It seems like any workable solution islight-yearsaway -- literally. Some researchers think the answer to our energy needs rests in thestars. From wind turbines onMarsto helium-3 fusion, people are increasingly looking to extraterrestrial sources for theEarth'senergy needs.
Advertisement
One of the sources they're looking at ishelium-3to use in nuclear fusion reactions. As opposed tonuclearfission, which splits anatom'snucleus in half,nuclearfusioncombines nuclei to produce energy. While nuclear fusion has already been tested with the hydrogen isotopesdeuteriumandtritium, those reactions give off the majority of their energy as radioactive neutrons, raising both safety and production concerns. Helium-3, on the other hand, is perfectly safe. It doesn't give off any pollution or radioactive waste and poses no danger to surrounding areas.
氦的同位素元素,helium-3 has two protons but only one neutron. When it's heated to very high temperatures and combined withdeuterium, the reaction releases incredible amounts of energy. Just 2.2 pounds (one kilogram) of helium-3 combined with 1.5 pounds (0.67 kilograms) of deuterium produces 19 megawatt-years of energy [source:Artemis]. Roughly 25 tons of the stuff could power the United States for an entire year [source:Wakefield].
The only problem is we don't have 25 tons of helium-3 just lying around. But conveniently, themoondoes. In fact, scientists estimate our lunar rock contains more than 1 million tons of the element. The energy stored in that much helium is 10 times the amount of energy you'd find in all the fossil fuels on Earth [source:Artemis]. If you put a cash value on it, helium-3 would be worth $4 billion a ton in terms of its energy equivalent in oil [source:Wakefield].
唯一的问题是实用性of extracting the helium and fine-tuning the fusion process. Current fusion reactors have yet to achieve the sustained high temperatures needed to produce electricity, and helium-3 extracted from the lunar surface would require lots of refining since it exists in such low concentrations in the soil.
The most promising space-based fuel source seems to be one we already have here on Earth. Find out why even the Pentagon is looking beyond our own backyard for solar power on the next page.
Advertisement