Is Fusion Power confidently feasible in theory?


I know the joke “It is always 50 years away”. I just was wondering if the body of work since 90s which is what the popular level of scientific knowledge is at, including mine – did that notion change? Is fusion technically “all good in paper” and it is an issue of reaching right material technology to harness it, or is it a more complicated complication?

P.S. I know Fusion is real, because stars. I am asking if it is possible on paper in the form factor of a generator.

In: Engineering

It is more than feasible in theory, we seem to be getting close to getting it in practice.

People are confident enough about that in France millions and millions of dollars have been invested into constructing the first experimental fusion reactor.

It’s actually already mostly built and being tested, with the goal of achieving fusion by the mid to late 2020s.

Edit: By achieving Fusion I meant in a stable, efficient, manner where we are able to harvest energy from it. Fusion tests have been done before (and there’s obviously Hydrogen bombs, nuclear fusion bombs)


Fusion isn’t just real “in the sun”. We can do fusion reactions already here on earth with technology.

The tricky bit is that it takes more energy to make the fusion occur (safely) than we can harvest from the reaction.

So.. making it a power positive generator is being worked on, making fusion happen is possible to do in your garage (with a few thousand bucks of parts and some knowledge of electronics and vacuum systems)

In order for “fusion power” to exist, we need to produce more energy from the reaction than the energy cost of sustaining it. The current record is around 70% (0.7) which is still less than break even. We’ll need to get to around 5-10x break even to generate electricity on a practical scale. The ITER reactor currently being built is the most funded fusion project. It aims to reach 10x break even for 5-10 mins at a time. ITER won’t produce electricity because it doesn’t have a turbine – the heat generated will just be discarded. But if it succeeds, we’ll be able to build another reactor (DEMO) which will be even more effective. The roadmap includes a third reactor, PROTO, which will serve as an actual power plant, with turbines and other equipment to produce electricity.
There’s still a *lot* that needs to be done before we see commercial fusion power plants.

– Reach 10x break-even on energy out/energy in
– Sustain the reaction for long enough at a time to be practical. The expectation is for reactors to run continuously instead of mere seconds at a time.
– Effectively breed tritium in sufficient quantities, as this is required to fuel the reactors. The fusion reactors themselves are being designed to breed their own tritium.
– Develop new materials that can survive facing the inside of the reactor chamber for long enough to be practical
– Develop methods to perform remote maintenance/material replacement on the highly irradiated reactor chamber

These barriers are pretty significant, but it’s all at least theoretically possible. Hopefully it’ll also be economically feasible to run them commercially. Fusion does have to compete with other low carbon methods of generation e.g. solar+wind+energy storage.

There are reasons to be optimistic about fusion power. Here is the current timeline:

* 1952: Fusion power was achieved, though at a net negative energy output (useless as a power source). We have never achieved fusion with positive output as of today.

* 1988: [ITER]( project initiated = the first fusion plant with a planned net *positive* energy output.

* 2007: ITER construction commences in France.

* 2025: Assembly of ITER is planned to end and plasma may be achieved.

* 2035: Fusion with net positive energy output.

However, ITER will not be hooked up to any grid, and will not be used to generate electricity. That will be reserved for the next project called [DEMO]( (assuming ITER is successful). DEMO has been delayed since ITER has been delayed, but this is the current plan:

* 2040s: DEMO construction commences.

* 2050s: DEMO operations may commence.

So with the current progression, fusion is 15 years away.