Scientists and engineers are very confident that nuclear fusion energy will one day be a reality. The technology offers clean, affordable and almost limitless supplies of energy. There are, however, some serious technological problems to be solved.
What are the problems with nuclear fusion?
The technology will use the same process that converts hydrogen into heavier elements in the cores of stars, thereby releasing large amounts of energy. These reactions occur in ‘plasma’ – where atoms have been stripped of their electrons – at enormous pressures and at temperatures exceeding 10 million°C (18 million°F).
Without the high pressures found in stellar cores, replicating these nuclear reactions on Earth requires even higher temperatures; about 100 million°C (180 million°F).
Heating nuclear fuel to these kinds of temperatures, safely confining it, maintaining its stability and extracting the resultant energy, are the main challenges for fusion energy. There are many competing engineering solutions to these problems.
Potential solutions
One such solution confines the hot plasma using strong magnetic fields so that the plasma is held firmly in a ‘toroidal’ shape (or doughnut). The magnetic fields also squeeze the plasma to increase the pressure. Then, a powerful electric current is induced in the plasma.
Microwaves and/or accelerated particles are also fired into the fuel increasing its temperature until nuclear fusion reactions begin. The released energy, in the form of fast-moving neutrons, is captured in a ‘blanket’ surrounding the plasma.
What progress has been made?
Currently, engineers have succeeded in producing fusion energy for short periods of time with a small amount of energy captured. Although the research is encouraging, we may not be able to fully solve the engineering challenges for another 30 years or so.
It’s more or less certain that one day nuclear fusion will supply humanity’s energy needs from fuel that’s cheaply extracted from plentiful seawater. The technology will produce no harmful by-products, radioactive waste or greenhouse gases, and will be very safe to operate.
Read more:
- Why do both fission and fusion release energy?
- Why does the fusion of hydrogen in stars release energy?
- Clingy atoms and catastrophic iron: The strange science underpinning nuclear fusion
Asked by: Jacqueline Burton, Worcester
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