Original URL: http://www.theregister.co.uk/2013/09/27/someone_must_have_a_thorium_reactor/

Thorium and inefficient solar power? That's good enough for me

I'm talking technology, not politics

By Tim Worstall

Posted in Science, 27th September 2013 09:32 GMT

Comment So we're all back from our hols, noses down to the grindstone for the run into Crimble: time for some idle speculation on the future of our energy production systems. Or if we're to be purist about it, our energy production/transformation systems.

We will, thankfully, leave entirely aside the complete dog's dinner that our current Lords and Masters are making of it all and try to look at technological trends rather than political actions.

The most cheering thing I've heard recently on this subject is that the price of thorium is now positive. That might not mean much without explanation, so here goes: There's thorium in all sorts of minerals from which we already extract interesting metals. The tantalite and columbite that we make our capacitors from for example: there's enough in the wastes from their processing that old factories that used to do this are now Super Fund sites in the US.

Vast sums of money being spent carting off the lightly radioactive wastes into secure storage (actually, just to piles by uranium mills). And if you actually happen to have any thorium around, as I do, getting rid of it is a very expensive proposition.

The usual solution to this sort of problem is that you refine whatever it is up to a useful commercial purity then sell it. But there's almost no one out there still using thorium: thus the price of thorium, given the disposal costs, is actually negative. Until just recently, that is.

Lynas, which has built a new rare earths refinery in Malaysia, will have thorium as a byproduct (there's always Th in your rare earth ores). They've announced that they're getting offers to actually buy it from them: the price has turned positive.

Now, OK, that's possibly only a matter of interest to metals geeks like myself: but what it actually means is that someone, somewhere, is being serious about starting up test runs of thorium reactors. It's the only possible use for the material these days in any quantity.

If someone's buying then someone is at least considering filling up a test reactor. My best guess is that this is the Indian research programme: although it could, possibly, be the Russian one and there are rumours of a Chinese as well.

Which I take to be cheering news: for there's no particular problem with thorium reactors. The engineering's pretty well known, it can't go bang, all it really needs is someone to actually build and test at size the technology. And, as I say, if thorium has turned positive in price then I have to assume that that's exactly what someone is doing.

I am making the assumption that we'd all like to have some method of generating electricity that doesn't involve pumping more CO2 into the atmosphere. Assuming that, a safer and cheaper form of nuclear as above sounds like a pretty good idea.

Some of the other technologies that are being touted don't look so good though. We've had windmills in Western Europe since the 12th century so we could assume that they're a pretty mature technology. And certainly, no one is predicting that there's going to be any great advance in their efficiency in the future. Which is a problem given their cost and intermittency. There are some marginal gains possible (they're the largest market for scandium, my particular metal, at present. Adding it to the aluminium alloy of the blades allows you to run them in higher wind speeds) but no more leaps forward.

And as to offshore wind: it is more expensive – and there's no marine engineer I've found who thinks that anyone has looked seriously at the problem of maintenance of metallic structures in the salt water of the North Sea.

Much the same problem seems to afflict the various ideas for trapping wave energy and the like. The sea is simply a harsh environment. Anything metallic does not last all that long out there.

Tidal, well, the problem there is that it just doesn't stack up financially. Looking at the Severn Barrage, the second largest tide in the world, we find that the bigger we build it, the more money we lose. Absolutely every design anyone's come up with (including that being pushed by Peter Hain at present) has a negative net present value. In plain English that means it loses us money.

A load of hot water

Hydro and geothermal have promise: but they're not generally deployable. You can do them in certain places but you can't do them everywhere and there aren't, at least as far as we know just yet, enough places where you can to power us all. There are minor useful sources like biogas but they are, in the face of energy demand, most definitely minor. Biofuels just starve poor people which isn't the aim at all.

Which leaves us really with the big three. Some advocates of fossil fuels like to talk about carbon capture and storage but that meets what is probably an insuperable problem. You end up spending 40-50 per cent of your fuel in the capture of the carbon and this doesn't reduce with scale. So even if it can be made to work (something no one has as yet managed) it's going to be expensive.

Nuclear, uranium type nuclear, many of us here will think that it's just a great idea. Unfortunately many who share the planet with us don't. It may even be true (actually, it is) that the radioactive release from Fukushima is, per hour, half that from the hourly consumption of bananas around the world. But that sort of logic just isn't going to convince people.

Here comes the Sun

Which really leaves us just with solar as the final possible choice. Which could be very depressing: it's expensive and it's intermittent again. We've no decent storage system (batteries would be waaaay too expensive at any scale) and so we might have to do what certain Greens so dearly hope we will do – go back to using energy when it's available rather than this luxury of using it when we want to. Except it is possible to see a system that would indeed work: or at least could do so.

The really interesting point about solar PV is that it's getting cheaper: it's been around 20 per cent a year (or 4 per cent a quarter) for a decade or more. This isn't just reliant on that glut of stuff from China. This is much more like a variant of Moore's Law, and why shouldn't it be? Making a solar cell is analogous to making a computer chip.

We've also got at least one more major design change possible: the switch to multi-junction cells. Use some indium, some gallium, some germanium, all in the same cell in order to collect photons of different energy levels and we can, already in the lab, get efficiencies of 40 per cent. And there's so much damn sunlight falling on the planet that we really wouldn't need to cover much of it at that level to power us all.

Which still leaves us with our intermittency problem. And this is where I rather break step with everyone else. I think that solid oxide fuel cells will be the solution here. They too are subject to a variant of Moore's Law. It is drawing circuits on a chip and we should get better at it over time, so I do expect them to plummet in price over said time. And the system would be to run solar, some electricity is used at the moment of production, some to electrolyse water. Yes, an inefficient process, but that hydrogen is then used to power the fuel cells as and when needed.

Now before an engineer starts shouting at me about how inefficient electrolysis is, I'd like to offer up a reminder that what we actually care about is cost, not efficiency. There's so much energy available that we'd be entirely happy with that efficiency loss as long as it is cheap enough. And that is what I think is going to happen.

Not, obviously, next year. But if the current price of solar PV is $1 per W, which is about the current capital cost, I can't actually see a reason why that won't be 50 cents within the decade and then going on getting ever lower. At which point that electrolysis is going to look pretty good as the basis of our battery or storage system utilising the fuel cells.

Such a hydrogen economy won't work if it's centralised: the problems of long term storage or transport of H2 are just too large. But as a decentralised system, at any one point trying to hold a day or two's worth of hydrogen it could, I think. Which really brings me to the real point of this piece. Above I've given you an outline of my thinking. But you guys know a great deal more than I do about energy and Watts and power and joules 'n' stuff. So why am I wrong, why am I full of it?

If solar gets cheap enough then we'll be happy with the inefficiency of electrolysis as a method of storage and fuel cells as the extraction from storage method. What is wrong with this idea? ®