Fusion is cool and it would be a very nice accomplishment for mankind. But it's kind of like going to the moon. The benefits will be offshoots of the journey rather than the journey and goal itself. Basically, if we want commercially viable and global use of fusion, someone needs to fix the problems below (talking here about D-T fusion designs and not aneutronic concepts). Not being negative, just pointing at the walls that need to be scaled.

1. Cost. The big problem here is that fusion does not address the main impediment of current nuclear fission. It's going to be really expensive to build power plants that are about similarly sized to fission power plants and more complicated (ITER is $65B... other projects are in the $5B range). They will still be massive construction projects. Renewables have proven that you have to manufacture your power systems in factories to lower costs rapidly. At the end of the day, fusion is going to be construction with all its associated delays, cost overruns, and low productivity. Can't really fix this without going much smaller and simpler, and that's not really an option based on physical/engineering requirements.

2. No current functional prototype. How long does it take from functional prototype to large-scale deployment, especially considering the massive regulatory overhaul required? eg. 50 years for aircraft? That might be fast enough.

3. Lots of very difficult engineering to deal with all the neutron damage and extreme temperature gradients. Million degree plasmas, 600 degree coolants, -40 degree super magnets, all within a few meters = nightmare. It's quite a hassle, but there are lots of smart people working on this. Can probably throw more money at this.

4. Not safer than fission. Yes, no long lived fission products for fusion and meltdowns are more difficult. But reactor damage and tritium release are probably more likely than in fission. Fusion power plant would be a lot more complex (more parts and systems) and has lots of tritium (tritium likes to escape from where you put it and diffuses through metals) with tritium processing facility to breed and fuel the reactor. Tritium has 10 year half life and not good for you when ingested. Essentially, lots of radioactive material handling + lots of equipment to maintain = higher chance of small accidents. See page 10 in link at bottom. Can probably throw more money at this.

5. Proliferation. Fusion reactors have lots of neutrons and tritium. Neutrons can be used to breed weapons material simply by placing normal uranium or thorium in the neutron flux. Tritium is used to boost nuclear weapons (just a bit of tritium drastically lowers the plutonium required). Is the only we to solve this state controlled fusion power? How can that be market competitive?

6. Probably only good for electrical power. While this is really just a limitation, it illustrates that fusion, should 1-5 be resolved, is not a magic bullet. You can't do much with it other than make electrical power. The power plants are too big to use for distributed process heat or hydrogen production.

Lidsky's often ignored 1984 paper: http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trou...