Earth Talk August 11, 2016
Dear EarthTalk: What is fusion energy and why are environmentalists so bullish on it? — Mickey Brent, Milwaukee, WI
Nuclear fusion may be the most promising energy source that most of us have never heard of. Scientists first discovered fusion as a potential energy source in the 1930s and have been quietly working on it ever since. Only recently, given societal pressure to find alternatives to fossil fuels, has fusion started to capture the attention of the media and policymakers — and now researchers are hoping the process can become a key source of safe, clean, reliable energy in the near future.
Nuclear fusion is the fusing of two atoms into one. Fusion is very different from fission, in which atoms are split in half. Although both emit energy, fusion emits much more. Fusion takes an immense amount of heat and pressure and is the reaction that happens inside of stars, including our own sun. The temperature at the center of the sun is around 15 million Kelvin (27 million degrees Fahrenheit)!
Scientists have achieved temperatures of around 100 million degrees inside experimental fusion devices but have yet to make the process net energy positive. The issue with doing reactions at such high heats is that the heated substance cannot touch anything or the container will melt. Therefore, fusion reactions are done in a donut of floating plasma, suspended by magnetic fields.
When compared to other energy sources, fusion energy seems like it might be our best bet in the long term. Compared to fossil fuels and renewable energy sources, fusion is wildly more efficient and no more dangerous. Fusion is three to four times more efficient even than nuclear fission, without the downsides such as the risk of nuclear meltdown or dirty bombs.
While nuclear fission requires uranium to function, fusion reactors only require deuterium, which occurs naturally in seawater, and tritium, which can be produced through a reaction of deuterium and lithium. These low raw material costs cause fusion to be considered a potential source of limitless energy.
Due to the low radioactivity of fusion, even in the case of an explosion, radioactivity would be contained to the reactor site. Fusion reactors’ small input and extremely high output have made them a popular idea.
So what are the drawbacks of nuclear fusion? Or is it the perfect energy source? Most critics of fusion energy point to the timeline as its greatest weakness. The majority of projections see 2050 as the first year fusion reactors could be commercially available. This is too late for fusion energy to solve our current energy crisis. Some environmentalists claim that funding for fusion energy could be better spent on renewable sources such as solar and hydro that give us clean energy now.
Another concern with fusion is public opinion. People tend to be wary of anything nuclear, if only because of the incredible devastation of nuclear bombs. While nuclear fusion is far safer than fission, many activists in France, for example, are protesting all forms of nuclear energy.
The biggest fusion energy project in the world is called the ITER which means “the way” in Latin. ITER is located in Southern France and funded by the European Union, the US, China, India, Korea, Russia and Japan. ITER will be a fusion reactor used for research and is currently under construction. Current plans are for ITER to be ready for the first test of plasma by 2025. The main other research on fusion energy is being done at the Massachusetts Institute of Technology (MIT).
Though commercial fusion reactors are far from a reality, the abundant raw materials and high safety, paired with enormous energy output, make it an outstanding possibility for the future.
Fusion 4 Freedom editor’s note: Princeton Plasma Physics Lab has been a worldwide leader in magnetic confinement tokamak based fusion research since the mid-1970s. Additional fusion research in America is being conducted by Lawrence Livermore National Labs (indirect drive Inertial confinement at NIF) as well as Sandia National Labs (Z Machine) and Los Alamos National Labs (proposed Plasma Jet Magneto Inertial Confinement.)