Energy security

Fusion energy’s greatest weakness — its timeline

Q: What is fusion energy and why are environmentalists so bullish on it?

— MICKEY BRENT, MILWAUKEE

A: 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.

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 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.