This week’s question was asked by a friend.
QUESTION: How can we get more energy from the sun?
ANSWER: We know we have dwindling supplies of fossil fuels − coal, oil, natural gas,and shale. That means we’re in need of new ways of powering our planet. Fossil fuels are hydrocarbons formed from the remains of dead plants and animals. Even though some of these fossil fuels may last for a few hundred years, there is a finite supply.
Our nearest star, the sun, offers more than one solution to our energy needs. We’re already harnessing the sun’s energy to produce solar power. Photovoltaic cells (solar cells) produce a direct conversion of light to electricity.
It may seem that solar energy is essentially free; however, creating the solar panels comes at a very high environmental cost. The mining of the materials and the manufacturing of the panels is costly. In addition, the output of solar panels is quite low compared to traditional means of generating electricity. Solar energy is here to stay and will remain an important slice of our energy needs. But it is not the complete solution.
Another idea is to use the energy of sunlight to create electricity to break water down into its constituent parts of hydrogen and water, a process called electrolysis. The hydrogen can be used to provide clean energy for cars and trucks. It’s the cleanest energy possible, no pollution. Unfortunately, the process is quite on the expensive side.
Hydrogen-powered cars are being developed these days. The whole infrastructure of manufacturing, transporting the fuel and fueling stations must be worked out. Safety considerations are primary. Like solar, hydrogen is here to stay and will remain an important segment of our energy needs. But it is not the complete solution.
Which leads us the ultimate use of the sun. There is ongoing research recreating the process going on in the sun itself. Fusion is the activity that makes the sun shine. If we can harness that fusion, we just might solve the energy needs of mankind forever.
We are familiar with the process of fission. Fission is the splitting of atoms, usually uranium, that produces a tremendous amount of heat energy. Controlled fission is the process that goes on in a nuclear power plant. Uncontrolled reactions are atomic bombs. Not to fret, nuclear power plants do not have the proper fuel to explode.
Fusion is the process of squeezing together lighter atoms to make bigger atoms. Fusion is the reaction that goes on in the sun, where lighter hydrogen atoms are fused together to create heavier atoms of helium. A loss of mass occurs and this loss is turned into pure energy in accordance with Einstein’s famous equation E = M C2. The total mass of the new atom is less than that mass of the two separate atoms. The missing mass is given off as energy.
Fusion occurs in an H bomb or hydrogen bomb. Tremendously high temperatures are required. Where do those high temperatures come from? An atomic bomb (A bomb) is detonated. In actual practice, the fusion material is packed around the atomic bomb.
The advantage of fusion over fission is that there is no nuclear waste to contend with. Whereas fission must be controlled and can “get away from you” as happened at Three Mile Island and Chernobyl, you have to work very hard to get fusion to even occur. High temperatures and high pressures are required.
Thermonuclear fusion research has been going on since the 1950s. If harnessed, the payoff is big, practically no radiation, no waste, no environmental pollution. The fuel is not uranium but simple water.
So far scientists have not gotten more out of the fusion reaction compared to what they put in. When will fusion power be commercially feasible? Well, in about 20 years. But they have been saying “in about 20 years” for the last 60 years.
Fusion power will happen eventually. In the meantime, we rely on a mixture of fossil fuels, nuclear, solar, wind, hydroelectric and biomass.
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Larry Scheckel is a retired Tomah High School physics teacher.