The old joke is that fusion power is 30 years in the future and always will be.
There's been a flurry of publicity and articles lately about supposed breakthroughs in fusion power, leading at least one writer to declare that "fusion power is about to become a reality."
Unfortunately, the truth is much less exciting: There's a lot of interesting experiments going on and some new approaches to developing fusion reactors. But we are still a very long way--at least 30 years--from actually putting a meaningful amount of fusion power on the grid.
At present, the most advanced fusion experiments still require a lot more energy to power the reactor than the fusion reaction generates. So talking about commercially feasible fusion power at this stage is a little like talking about building steam engines before we've figured out how to make fire.
The road to fusion power has a number of mile-markers, none of which has been achieved yet:
- An experiment has to produce more energy from fusion than it takes to power the experiment. (In 2013 the NIF claimed to have achieved this, but they ignored the substantial inefficiency of the lasers used to power the experiment. So most people still say that we haven't yet passed this milestone in any meaningful sense.)
- An experiment has to be sustained for a significant amount of time with positive net energy production. (So far all fusion experiments with meaningful energy output have lasted only a short time, nowhere close to one minute, much less the weeks to months required for practical power production.)
- An experiment has to capture the energy produced in a usable form for power generation. (I am not aware of any actual experiments to test ways to do this.)
- A pilot plant has to produce power over a period of months to years.
- A commercial test plant has to produce power at a cost that's close enough to other energy sources that it could be competitive with further development and mass production.
- Then--and only then--are we truly within a few years of actually powering the grid with fusion. The final milestone is to deploy multiple commercial scale reactors and put power on the grid at a competitive cost over the lifetime of the plant.
It is possible that a major breakthrough could get past the first few milestones in just a few years. It's also possible we could spend another half century stuck on trying to get to energy break-even.
Or even with a major breakthrough, it could turn out that building a commercial-scale plant is much too expensive for the amount of power produced and the technology goes the way of hydrogen powered cars.
Fusion power is definitely worth further research. If we can ever figure out how to make it work, it is plausible that fusion can be a practical and economic power source without many of the drawbacks of nuclear fission reactors.
But it turns out that fusion power is a really hard problem to solve. Progress has been very slow, and while recent developments are exciting, it's still at the very earliest stages. Anyone who claims fusion is just around the corner is either drinking a lot of kool-aid, highly misinformed about the state of the technology, or being intentionally misleading.