Nuclear Fusion Project, Iter begins assembly | Hacker News Reader

Nuclear Fusion Project, Iter begins assembly

theguardian.com

73 pointsandyjenn31 comments

I'm not sure where people are getting this terminology of "unlimited" energy from fusion. Nothing in the universe is unlimited. The earth's supply of deuterium and/or tritium is not unlimited.

It's also not infinitely "clean" energy. A fusion reactor is not a black box that is built once and never again maintained or rebuilt, or doesn't use any consumable components besides fuel.

We already have the technology that gives us nearly clean energy, namely nuclear (fission) reactors. If we truly want to reduce CO2, we should be ramping up nuclear power, as a bridge to switching to renewables in the long term. If only nuclear power wasn't so politically... radioactive.

The same place that fossil fuel advocates get "unlimited" for fossil fuels.

They just mean "a lot"

Please, don’t act like nuclear fusion is a simple iteration of nuclear fission. It’s a fundamentally different process.

Fusion would provide (much) more energy, use (much) less radioactive inputs, and produce (much) less radioactive outputs. Fusion is significantly safer. In a failure mode the fusion reaction will lose containment and die out like a fire without oxygen. Fission rods will continue to produce heat & radiation in a failure mode, and all failure modes of a fission power plant need to account for this.

I’m actually pro fission, because the risks of fission are lower than the risks of coal, oil, and natural gas. Yes, the article was hyperbolic. However, you’re under-hyping the advancement of fusion. When fusion comes it will be politically palpable globally, cleaner than fission, and it will reduce the cost of energy significantly.

> fission rods will continue to produce heat & radiation in failure mode

Not all fission designs require solid fuel rods, e.g. LFTR, which coincidentally has a failure mode that is much safer than solid fuel fission reactors.

The actual reactive core is safer, it cannot meltdown, but we don't know much about the support systems just yet. With all that energy running through the magnets, the pressures involved in the contemplated energy collection system, there is a potential for catastrophic failure modes. A steam explosion isn't nuclear bomb but can still kill. Fusion is safer than fission but I wouldn't yet call it safer than solar panels.

Depends how you're measuring risk. Microdeaths per megawatt-year?

The thing about a fusion plant is that there likely won't be that many people on site. Failure modes for the most part ought to look like conventional explosions, which we largely know how to mitigate where they're likely.

What worries me, with the sequence of plants, starting with ITER and DEMO, is that because of the scaling laws that seem to be involved, we're heading towards very few gigantic generators, where they're each responsible for such a large proportion of the power supply that we couldn't cope with any one of them going offline. The immediate power loss itself could be responsible for loss of life.

>> this terminology of "unlimited" energy from fusion.

All language exists in context. This isn't a math prof talking of 1/0-type infinity. This is a practical infinity, ie so much energy that we cannot contemplate how we would run out. With literal oceans of hydrogen at our feet, and more landing on earth daily in the form of comets/asteroids, speaking of infinities is understandable.

Deuterium is measured in parts-per-million in the universe at large. Lithium is parts per billion, and in theory you can feed hydrogen into a white dwarf and harvest lithium from the novas. For a Kardashev III civilization just harvesting existing deuterium and lithium this is at least 1MJ/kg of specific energy over all the matter in the galaxy (if I did my math right). Not quite unlimited, but roughly as if 10% of the galaxy was made of hydrocarbon fuel.

Virtually unlimited clean energy like that would allow us to vacuum back the carbon dioxide from the atmosphere and reverse the damage we’ve done in the past 200 years, while allowing us to continue with our fossil fuel infrastructure.

It’ll also enable unlimited desalination which would allow more crops and a lot more food, ending a whole mess of problems.

I'm honestly surprised where these fantasies come from.

In order to get that energy you'll have to build a hugely complex industrial installation. That won't be for free. It won't be easy. If it will even be possible remains to be seen. You'll still need transmission lines and other infrastructure that costs money.

Whether it'll work and if it works whether it will be cost competitive to renewable energy (still improving and getting cheaper) remains to be seen. But it almost certainly won't be "virtually unlimited".

I feel it will be waaaay cheaper than any alternatives though (order of magnitudes, that we are likely forced to be spending on this regardless).

If success was guaranteed money wouldn't really matter.

Though part from success we have deadlines etc. that complicate the matter further. Regardless, this is welcome news.

From misunderstanding exponential growth, which it will jump start. They think people will continue to live as they do now, just with lower electric bills.

Norman Borlaug on receiving the Nobel Prize for the green revolution, said it well:

"The green revolution has won a temporary success in man's war against hunger and deprivation; it has given man a breathing space. If fully implemented, the revolution can provide sufficient food for sustenance during the next three decades. But the frightening power of human reproduction must also be curbed; otherwise the success of the green revolution will be ephemeral only.

Most people still fail to comprehend the magnitude and menace of the "Population Monster"...Since man is potentially a rational being, however, I am confident that within the next two decades he will recognize the self-destructive course he steers along the road of irresponsible population growth..."

We haven't steered away from that course. Fusion would accelerate us on it. If we have to come into balance at some point, why not now instead of when we exhaust fusion's potential? Why does this community think we can solve every technical problem from the moon to Mars to fusion, but we can't live in balance with nature?

Wealthy countries around the world are seeing collapsing fertility rates and exploding carbon & resource use. We can’t live within balance with nature because of the second item, not the first.

Fusion and space colonization can get us to sustainably supporting trillions of human lives in the solar system alone. Fundamentally there is no living in balance with nature; the only barrier that can’t be overcome is the heat death of the universe, and there’s no living in balance with that, either.

>> but we can't live in balance with nature?

With greater prosperity comes reduced birth rates. This has been seen across the globe in a variety of cultures. The thinking goes that if fusion, cheap energy, can lift people out of poverty it will contribute to decreasing population growth.

Except that we actually have steered away from this course, though not through any conscious decision. More economically developed nations tend to have lower birth rates, with the most affluent somewhat below the rate of replacement. In my opinion, the best method to curb population growth is to get more of the world up to that standard - and energy production is evidently a huge factor. See for instance the work of Hans Rosling.

And either way, energy-intensive practices wouldn't accelerate environmental destruction, they would enable us have a smaller footprint in the natural world through, for instance, vertical farming (currently infeasible because electricity is more expensive than sunlight), carbon capture, switching from aquifers to desalinated seawater, etc.

reverse the damage we’ve done in the past 200 years

From the little I know about it, this damage you talk about only means getting CO2 levels back to normal. Great, but by the time that becomes realistic (seems no sooner than 2050 since that's about when there will be a demo, and only a demo) it's getting a bit too late for all side effects, i.e. global warming and all damage which comes with it. Add to that the whole latency of the system, and I'm not too optimistic.

Someone I think on a slashdot post calculated that we'd have to process about half the planet's atmosphere to get back theCO2, that is liquefy that much atmosphere to collect the CO2.

Then we'd have to put I guess hundreds of cubic kilometres of liquid co2 somewhere. I long ago lost any hope we will deal with it.

Taking in mind absorption rate by plants, I wonder if you could do a controlled release in somewhere like a rainforest such that a minimal amount would make it back into the atmosphere and a majority would be taken in by trees and plants. Alternatively build large green houses and vertical farms and pump it directly into there.

Plants are not a sink for CO2, just a transition point. Any CO2 that is taken up by the plant gets released when it dies and decays.

Couldn't you bury the plants, the same as trees, sequestering the carbon underground?

If you have the energy to distill a large proportion of the earth's atmosphere you have enough to crack the O2 from the C and not mess with plants etc.

True, and I had not considered that. I like the idea of growing more trees though.

Trees = good, I'm with you.

You could do that. It is how most fossil fuels got underground in the first place. OTOH if you have the ability and available energy to bury all of that plant matter, maybe you could instead just convert the CO2 directly to carbonate and skip the part with the plants.

You're missing the trick. If you've got "free" energy, you can reverse the process: combine the CO2 with water and turn it back into high density hydrocarbon solids that you can safely bury. Or, if you can pick the hydrocarbon, use them in construction.

Doesn't help with the amount of gas you'd need to process, but the storage part is doable.

Very good point, thanks.

200,000 years later: nuhumans "wooah, I just discovered that there are all these hydrocarbons buried in the ground. These would just be perfect for this industrial revolution we are having"

That would honestly be a huge upside to this approach. We've already extracted most of the easily accessible energy resources, so if our society fails, the next one will have a much harder time moving from agrarian to industrial.

> vacuum back the carbon dioxide from the atmosphere

For what it's worth, it apparently is much easier to scrub CO2 from sea water than from atmosphere.

Already discussed here: https://news.ycombinator.com/item?id=23979608

Reply on news.ycombinator.com