Fusion vs fission
Fission (today's reactors)
- Splits heavy atoms like uranium
- Proven: decades of commercial power
- Long-lived radioactive waste
Fusion (the goal)
- Joins light atoms like hydrogen
- Fuel from seawater and lithium
- Much less long-lived waste
The challenge
100+ million °Cneeded to fuse hydrogen on Earth
~600 milliontons of hydrogen the Sun fuses each second
2022first experiment to get more energy out than the laser put in
Not yetcommercial fusion electricity
The 2022 result came from the National Ignition Facility in California.
Two main approaches
Magnetic (tokamak)
Magnets hold a ring of super-hot plasma
Laser (inertial)
Lasers crush a tiny fuel pellet
ITER
A giant international tokamak being built in France
Private companies
Many startups racing to build pilot plants
Sources: U.S. Department of Energy; Lawrence Livermore National Laboratory; ITER
Remember
Fusion has been shown to work in the lab; making it steady, affordable electricity is the remaining challenge.
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Answer key
- What does fusion do?Joins light atoms togetherFusion combines light nuclei.
- What powers the Sun?FusionThe Sun fuses hydrogen into helium.
- What happened at the National Ignition Facility in 2022?Fusion got more energy out than the laser put inIt was the first such result.
- About how hot must fusion fuel get on Earth?100+ million °COver 100 million degrees.
- What is a tokamak?A magnetic device that holds hot plasmaIt uses magnets to confine plasma.