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Comment by adrianN | Hacker News Reader

Can we stop with the "fusion will always be x years away" meme? Fusion is mostly a number of invested dollars away. A big reason why we don't have fusion reactors yet is because nobody invests sufficient amounts into the necessary research. Check this graph http://imgur.com/sjH5r from the old Slashdot interview

https://hardware.slashdot.org/story/12/04/11/0435231/mit-fus...

It's just disrespectful to all the brilliant physicists and engineers who work on the topic to belittle their efforts like that.

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> You might say that we’re not a certain number of years away from a working fusion power plant, but rather about $80-billion away (in worldwide funding).

That's a surprisingly small number for the impact nuclear fusion could make. I wonder why we haven't seen any billionaires taking up the challenge, even though this might be more impactful than space tourism or people on mars.

For context, that's over twice the size of the Gates Foundation. You have to compare that to all other possible investments, including energy startups that could pay off a lot sooner.

Note that SpaceX is set up as a business, not a charity; Musk may talk a lot about Mars but that's not really where the money goes.

The money funding SpaceX could hardly be allocated towards sustainable colonization of Mars in a more efficient manner. If you can think of one, please email Elon.

Sure, SpaceX has good business plan. That's the point. Building rockets only for a future Mars voyage and not making any money along the way would be a bad way to do it.

By contrast, fusion will only be a scientific research project for many years and many billions.

That's just the way it works. It cost a lot of money to develop rockets in the first place. Your comparison is simply not very meaningful.

My point is there is a big difference in how much money gets tied up for how long. (Capex.)

Time/budget predictions are hard, especially for cutting edge research. So predicting required funding until fusion is profitable sounds unreliable too.

The bottom like is that fusion energy is now engineering problem and not basic science problems. Engineering risks are more manageable and predictable.

It's like Manhattan project, you can do it if you want it bad enough.

This is simply not true. There are unsolved engineering problems and not just risks.

I think comparison with Manhattan project is appropriate. Manhattan project also had unsolved engineering problems, which they solved.

Fusion has fundamental engineering obstacles, not just unsolved problems.

The basic problem is that heat transfer limits guarantee that fusion reactors will be big and expensive (meaning: power density an order of magnitude worse than a fission reactor core, and probably worse than that.)

The core of a PWR fission reactor that one can build today has a power density of 100 MW per cubic meter. The power density of ITER (dividing the gross fusion power by the volume inside the cryostat) is 0.05 MW per cubice meter, 2000x worse. Other fusion designs aren't quite as ludicrous, but will still be much worse than fission.

The problem is that heat in the PWR has to get out of fuel rods that are 1 cm in diameter. The heat in a fusion reactor has to get out of a plasma vessel that is meters in diameter. The ratio of surface area/volume is orders of magnitude higher for the fission reactor.

that spot on. IMO Its mostly a funding issue. My bold prediction is that we will have net energy from fusion within a decade of the point where market Begins to price in the ultimate demise of fossil fuel based energy. sooner the FF projects start getting counted as stranded resources because of EVs & renewable quicker the money starts to flow into fusion research.

the other rapid development scenario would be some sort of fusion arms race between asia (ch/kr/jp) and the rest of developed world.

You have to admit that there is something to this meme, It seems like Fusion suffers from a lack of focus and direction. Ive heard all sorts of horror stories about physicists and engineers going off on fusion design tangents that pull funding away from more viable designs as far as energy-in/energy-out.

I understand that there is a level of experimentation and R&D that is guaranteed not to generate viable results but at some point you need to trim the fat, get everyone moving in one direction etc. This grand project has been going on for over 50 years at this point, It seems like we should at least have one design that everyone should be focusing on. If they had real, defined commercial goals (even if they miss the goals) it might be easier to secure funding because your average politician would see the benefit to them.

I'm not a nuclear engineer so take that all with a grain of salt.

It's hard to know what is a 'tangent' and what is the next breakthrough though.

As they say - if we knew what we were doing it wouldn't be research.

We have a design that everybody is focusing on. That's why they want to build ITER and DEMO.

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