We have long been aware that our problematic fossil fuels are also finite resources. So it’s no wonder that for decades physicists have pursued a long-shot approach to clean power—nuclear fusion. As the price of oil remains low, concerns rise that fossil fuel use will increase with all its commensurate environmental costs. Cleaner alternatives such as solar or wind have become more competitive, but still not that widely used. Nuclear power is always an option, but a controversial one.
There are two different forms of nuclear power, fission and fusion. Fission is the splitting of heavy atoms and harnessing the energy that is released; this process has already been achieved. Today’s nuclear plants run on fission, which produces highly toxic spent fuel as a byproduct. The reaction must be rigorously monitored to prevent meltdown. The nuclear weapons deployed during World War II worked on fission.
Nuclear fusion, on the other hand, rather than splitting an atom, collides two lighter atoms (typically hydrogen) until they fuse together into one heavier atom (helium). Two light atoms combined have a lot more energy than one heavier atom, so when the two fuse together the excess energy is released. The excess vastly exceeds the energy produced during fission.
Atomic nuclei are always positive, so in order to overcome the repulsive force of two positive charges fusion only occurs at extremely high energy levels, i.e. extremely high temperatures. The only place fusion occurs is in the core of the sun at a temperature of millions of degrees.
Therein lies the problem; it’s not so easy to simulate the core of the sun. Generating such high temperatures has been extremely difficult, and since the 1930s physicists have devised a variety of containment vessels that could foster the conditions required for fusion. By the 1950s, fusion had been achieved, but only inside a nuclear bomb. Scientists were confident that controlling fusion for energy production would soon follow.
Fast forward to the 1980s. Following the oil shocks of the 1970s, interest in clean, abundant energy was at an all-time high. Despite decades without any meaningful success, optimism prevailed. In 1989, scientists at the University of Utah announced something incredible; they had achieved fusion at room temperature. All that was required to solve the planet’s energy needs was a jar, some deuterium, and an electric current. This was believed to be physically impossible. And, in fact, it was. The Utah results are widely believed to have resulted from experimental error and wishful thinking.
Fast forward again to the present day. We are not much closer to fusion than we were in the 1950s. Technology has improved, now powerful lasers are available to superheat hydrogen. Despite billions of dollars-worth of lasers, recent progress has been incremental, and spectacular failures are still the norm. After fruitless decades many question whether controlled fusion is even possible. Many also believe that the vast resources spent on fusion might have been better directed to more realistic energy projects. There is no question that cleaner energy sources are needed. But only time will tell if fusion is the way.
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Sage Publications, Ltd
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Society for Science & the Public