| MadSci Network: Physics |
Thank you for your question Alex. Certainly in a time of rising gas prices and concerns about environmental pollution, your question is well placed. First, there does not appear to be a "perfect" fuel now or in the foreseeable future. But there are many options to fossil fuels. Short term fixes include taking advantage of our own environments. By that I mean solar, in which we capture the light of our sun and convert it to electricity; geothermal, where we use the internal heat of our earth to heat a fluid and thereby generate electricity; and wind and water, where we harnass their power to generate electricity. But solar power requires adequate sun light - does not work well in areas prone to cloudy weather. Also solar cells are not extremely efficient, which means they take a large surface area to power a home. The possibility of capturing sun light in space and "beaming" the energy to earth has its own set of serious technical and environmental problems. Geothermal requires reasonable access through the earth's crust (through weaker, shallow regions) and so are limited geographically. Such renewable sources could be used more effectively, but still their sum potential would likely represent a small fraction of our energy needs. And then there are the "off the wall" (i.e. cold fusion) announcements which sound too good to be true (probably for good reason). This leads to perhaps the "perfect" fuel you were thinking about: Thermonuclear Fusion. This is the power source for our sun. Deep inside the core of our sun, the temperature and pressure is so emmense that protons are fused together to make helium and release energy. The difficulty is that controlled, sustained fusion requires enormous temperatures and densities (millions of degrees). Fusion has been accomplished on the earth - for very short and uncontrolled periods (H- bomb) and for controlled periods which also required more energy be used to control the reaction than the energy released by the reaction. Nevertheless, progress is being made and the first fusion reactors may dot the horizon during the next generation. However, the first fusion reactors will be far from perfect. Fusion is so hard to achieve, it will likely be necessary to use deterium -tritium (both isotopes of hydrogen) in first generation fusion reactors. What makes these isotopes is the presence of neutron - meaning radiation and possibly radioactive waste. Now the problem of radiation in this reactor is no where near as severe as current nuclear fission reactors. But it certainly is far from perfect. Eventually, fusion could mature to true proton-proton fusion, yeilding clean energy and helium - especially if coupled with a direct energy conversion system in which the charged particles from the reactor are captured to generate energy. Its a worthwhile dream. But unfortunately it is not likely to be available for many years. In the mean time, it behoves us to be good stewards of the non-renewable energy sources as well as our environment and not waste what we have. I've attached some links you might find useful: http://www.nrel.gov/geothermal/geoelectricity.html http://fusedweb.pppl.gov/CPEP/Chart.html http://www.nuc.berkeley.edu/thyd/icf/IFE.html
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