Science Interviews

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Tue, 2nd Sep 2014

Do We Need Nuclear Fusion?

Mitchell Waldrop, Nature

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Is nuclear fusion really going to solve, or at least alleviate, some of the world’s energy problems? Would it be better to invest in renewable technologies instead? Mitchell Waldrop is the Features Editor for ‘Nature’ and Hannah Tooley has been asking him if nuclear fusion really is going to be all that we’ve been promised… the sun

Mitchell -   Well, of course, the biggest positive for fusion power is that unlike coal or natural gas, it does not produce any greenhouse gases, no carbon dioxide.  It’s not burning anything, at least not in the conventional sense.  So, it’s carbon free and good for the climate.  Coal of course is by far the dirtiest fuel in that sense.  Natural gas is somewhat better, but still, does produce quite a bit of carbon dioxide.  And if you're running an industrial society, if you're running factories, if you're running cities or for that matter, if you run electric cars, you need reliable power 24/7, whereas wind and solar cannot give you that.  They're valuable sources, but they cannot provide what is called base load power.  Fusion can do that, in principle.

Hannah -   Is it safe as other, say for example, wind power, we just need it to be a bit windy or solar power, it’s just got to be sunny, is this a safe method?

Mitchell -   Fusion power cannot blow up like an atomic bomb.  It cannot meltdown.  It can't do any of the things that we worry about with nuclear fusion power, which is a very different kind of process.  Fusion power will produce a relatively small amount of radioactivity a lot of the energy comes out in the form of neutrons, which makes the walls of the reactor radioactive.  That does create a waste disposal problem, but this nuclear waste, those radioactive waste, is not nearly as big a problem as the kinds of waste you get in nuclear fission because the radioactivity decays relatively rapidly within a century or two and would be completely safe to handle.  Contrast that with the spent nuclear fuel which will be dangerous for something like 20,000-30,000 years.  So in that sense, it is safe comparatively – be careful to what you compare it to. Coal, which of course, is very, very common, as the most common fuel that is currently in use.  The mining of coal is quite dangerous in terms of the health problems it creates in miners, in terms of the environmental problems it produces around the coal mines, and by the way, coal itself contains a certain amount of natural radioactivity - its actually more radioactive than certain types of radioactivity produced in the nuclear fuel cycle.

Hannah -   So, you mentioned earlier that renewables weren’t as efficient as we need them to be and fission is a bit too unsafe for us to go on.  But fusion, we’ve not yet had a positive power output.  So, which one of these options is most viable if any of them?

Mitchell -   Nuclear fission has its problems, but there are advanced designs that are much safer than the ones we’ve been using for 30 and 40 years.  There are designs that physically could not meltdown.  There are designs that could in principle, burn up nuclear waste instead of making more of it.  There's a lot of research, but right now, there are commercial nuclear reactors running right now and that for the most part have operated safely.  One of the problems that happened at the Fukoshima reactor in Japan, was that it was an old design.  It was designed dating from the 1970s and didn’t incorporate a lot of the safety features that other most modern designs now incorporate.  So, fission is quite viable.  Wind and solar of course are quite viable.  It’s simply that you can't always rely on them to produce power in a steady fashion.  Again, people are working on that – if you could store the power in gigantic batteries, that would solve that problem, but the problem is that nobody knows how to do that yet.

Hannah -   So, as demand for energy increases, do we actually need nuclear fusion?

Mitchell -   I would say it is a long term solution, because remember as the developing world – China, India, Brazil – all these countries which are fast entering the modern world and improving their economies and creating a middle class people who want to run their computers and their washing machines, so forth, they need huge amounts of power.  Right now, China is meeting most of those needs by building lots and lots of coal-fired power plants and creating huge amounts of carbon dioxide, not to mention ordinary pollution.  If everybody in the world were to aspire to a typical British or American middle class lifestyle, and they did it by burning coal, we would have hideous pollution.  We would greatly accelerate the emission of carbon dioxide and accelerate climate change and we would be in real trouble.

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Over time more and more renewable resources will be developed, but they aren't all without any consequences.  Hydroelectric is great, but it damages fisheries, and there is always a potential for earthquake damage to dams. 

Energy from solar and wind is inconsistent. 

Tidal energy sources could also be damaging to sea life, as well as being a difficult environment to develop. 

As far as fusion, ideally one would simply use hydrogen which is abundant in the world's water.  However, most of the current experiments use much rarer elements such as Helium-3. CliffordK, Wed, 3rd Sep 2014

Yeah, a good question. A lot of stuff matters there. It's the way we defined reality, as consisting primary of collecting things, money, to call it 'my own' :) We call it investments that need to give a return, and we invest in what gives us the most profits for the buck. That means oil, coal and methane. Nuclear is a hybrid, both giving us weapon material and energy, for a price. We think we can buy earth, and own it, and as we all agree on it we have this game we play until we die, by which time it doesn't matter what game we played.

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As for? "There are designs that physically could not meltdown."
Where?

Theoretically, or practically, existing? SA? Also, there has been no dismantling of a reasonably large nuclear power plant that I've heard about. Instead one can see people proudly point out that 'the reactor has been working well over its projected life length' :) Ah well..

It will be interesting to see the real costs, and whom will pay for them. yor_on, Tue, 9th Sep 2014

The cost of dismantling old reactors is determined by politics rather than physics. If you apply the same cost per life-year as is current in aviation safety ($30,000), nuclear power is wholly affordable, but if you use environmental protection agency costs (($8,000,000 per life-year) it isn't. As the average life is insured for around $100,000, I think the lower figure is applicable andthis should determine the  acceptable risk in undertaking an otherwise wholly beneficial exercise.

The physics problem is that the energy payback period of inherently safe reactors is rather longer than for inherently unsafe PWRs. If we started now, we'd probably run out of the oil needed to make the reactors before we had replaced all the fossil power stations with nukes.

The other problem is a public fixation with electricity.  It accounts for about 30% or less of our "final" energy use and absorbs nearly 50% of our primary energy sources. More coal, oil and gas is used directly in industry and transport: the economic and sociological problem will be to find a sustainable replacement for these.    alancalverd, Tue, 9th Sep 2014

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