subject: Nuclear fusion: power to the people?
posted: Wed, 06 Jul 2005 18:53:57 +0100


[the online version is full of links! - Stu]

http://www.theregister.co.uk/2005/07/06/nuclear_fusion/

Nuclear fusion: power to the people?
By Charles Arthur
Published Wednesday 6th July 2005 11:40 GMT

It's G8 week, and climate change is high on the agenda. And now that
even George Bush has acknowledged that climate change is (a)
happening and (b) is at least partly due to humans but insisted it
(c) should be tackled through technology, why not focus again on a
technology that's (1) happening and (2) partly controlled by humans?

That is, nuclear fusion. Unlike fission, already used to produce most
of France's electricity, fusion isn't commercial yet. Even its most
positive advocates reckon it'll be more than 25 years before a fusion
reactor could contribute usefully to the power grid ("useful" being
defined as a steady output of 1 gigawatt; the UK has about 42 GW of
installed electric plant).

But it does have one very important advocate, and another who is
coming along for the ride, and they're both G8 leaders. The advocate:
Tony Blair. The one along for the ride: George Bush. Plus it also
involves two other G8 nations, France and Japan, directly, as they'll
get tons of money from contracts to build the next stage in the long,
long road to commercial fusion.

Last week France was chosen as the site for the International
Thermonuclear Experimental Reactor (Iter) project, beating Japan's
bid. If it works, ITER will take in 50 megawatts of power and put out
between 500 and 1,000 MW. That's right - it could power itself.

Here's how. Fusion is what powers the stars. They burn by slamming
two hydrogen nuclei (protons) together, to produce a helium nucleus
(two protons) and some extra particles. (See the whole system here.)

On Earth, we cheat a little by fusing a nucleus of deuterium
(hydrogen with a neutron aboard) with one of tritium (hydrogen with
two neutrons), to produce a helium nucleus plus lots of energy in the
form of a "fast" neutron. Simple on paper; fiendishly hard in
practice. You have to heat the material to about 100 million
Centigrade until it becomes "plasma", confine it using magnetic
fields, and compress it so fiercely that you overcome the natural
tendency of nuclei to repel each other as fiercely as Steve Ballmer
encountering an iPod.

Deuterium is plentiful. There's enough in a bath to generate all the
energy you'd need in your lifetime. Tritium is trickier, produced
either from deuterium fusion, or other decay products. It's used in
nuclear weapons, exit signs that work without power, and some
illuminated watches.

If you can control the fusion reaction and keep it going, you produce
huge amounts of "fast" neutrons which heat up the reactor vessel.
That heat can produce steam which can turn turbines to generate
electricity. Nuclear waste? Well, the reactor walls might be a little
radioactive after you stop; but in 10 years' time you could reuse the
parts in another reactor. Tritium is poisonous, but wouldn't get out.
And the reaction can't run away like fission can; if the magnetic
"bottle" fails, the reaction stops.

Big science

The politics similarly involves bashing people's heads together at
sufficient pressure to produce a solid project and a fast-moving
schedule to make it happen. For years fusion was on the slow track.
That's because it's big science, and thus big politics are involved
to make it happen. Although the Joint European Torus project in
Abingdon, Oxfordshire, managed to generate 80 per cent of the power
put into it - falling just short of being self-sustaining - it
demonstrated what could be done. In 1985 Ronald Reagan signed an
agreement with Mikhail Gorbachev to work towards ITER, with the aim
of producing a prototype commercial reactor this century.

But in 1998 Bill Clinton's administration withdrew from ITER, citing
costs, and the US began going it alone with its own FIRE fusion
project.

And ITER will cost. The budget is estimated at $12bn - shared between
Europe, the US, China, Korea, Japan and Russia - and a lifespan of
about 30 years. Then again, that's only 6.6bn at present exchange
rates. That would buy you a British national ID card scheme; in fact
Britain's share is much less, and it could even generate 100m of
revenues for British businesses annually.

But what's remarkable is how fusion has abruptly moved up the agenda.
It's not for scientific reasons though, but politics. And it comes
down to one person: Tony Blair.

He's come under pressure at home from Professor Sir David King, the
government's chief scientific adviser, to do something on climate
change. In 2001, he headed a European panel looking for a fast-track
to fusion, and concluded (PDF) it was feasible. The problem is that
renewables like wind, waves and solar can't cover the energy
shortfall once the UK's nuclear power stations go offline around
2020; presently fission produces 25 per cent of the UK's electricity.

Building more nuclear fission stations looks the easy option, but
Margaret Beckett, at the Department of Environment, Food and Rural
Affairs, hates them and talks them down as fiercely as King talks
them up. She sees them as vote-losers because nuclear waste disposal
gives environmental groups a stick to beat Government with. By
contrast, the only criticism (though it's a zinger) environmental
groups like Greenpeace have of fusion is that it's a lot of money
that could be spent subsidising or building renewables now.

That makes fusion the politically acceptable solution. Professor King
likes it, Beckett doesn't dislike it, and the greens can't hang you
for it. So two years ago at a Camp David summit Blair himself
persuaded Bush to rejoin ITER and stop funding FIRE. (In such ways is
political goodwill generated by supporting the US over Iraq
recouped.)

So, note a key passage in Dubya's interview with ITN about how to get
around climate change: "If people want to come together and share
technologies and develop technologies and jointly spend - and spend
money on research and development, just like the United States is, to
help us diversify away from fossil fuels, [I am] more than willing to
discuss it. I know we need more nuclear power in order - nuclear
power, after all, is not dependent on fossil fuels and emits no
greenhouse gases."

Note he doesn't specify what sort of nuclear power, and how he does
emphasise coming together on R&D; though the US did oppose the siting
of ITER in France, preferring the rival site, Japan, which would thus
have got the guaranteed construction jobs and contracts. Why? Well,
which country supported the US on its Iraq adventure, and which
didn't? As we said - politics, not science, rules here.

But once the politicians have gone away, ITER's scientists can get on
with the task. Which isn't trivial. But right now they're as happy as
dogs with two tails, especially compared to a few years ago when it
seemed the entire fusion project would run into the dirt. The arrival
of climate change as a political hot potato has given their cause new
fuel, and they're burning it as quickly as possible.

Big question

The big question is, can it work? Can "hot" fusion ever be
commercial? We'll deal with that in just a moment.

But first, some think that commercial fusion is much closer than
grand projects like ITER make it seem. For them, cold fusion never
went away, just went underground, much like its "hot" sibling. The
publication in April of a letter in the science journal Nature by a
team at UCLA who apparently achieved small-scale fusion in a
laboratory has had some people agog.

The trouble is that it's not going to generate cheap electricity. It
seems to work, but doesn't scale: you can't get more energy out than
you put in. So this crystal-based technique could produce fast
neutrons, for radiotherapy or X-ray machines; but not a power
generator. "It's very interesting, but it's not a power source," says
Chris Carpenter, spokesman at JET. "These small-scale things aren't
viable because they don't scale up."

For that, you need something like ITER - because hot fusion does
scale, gloriously. ITER will only be twice the size of JET, yet
should generate more than 75 times as much power.

And the potential? "You have an energy market that's worth about $3
trillion worldwide annually, and electricity is one-third of that,"
says Carpenter. "If we invest big now in fusion, then it could pay
off. OK, perhaps it won't work; in that case we've found out sooner,
and we can try something else to generate the power we need. We
aren't saying fusion is the only option. But it's probably the only
non-polluting, large-scale option."

But what's changed since JET was built to make it any more likely
that fusion won't remain forever 30 years in the future? The
materials, says Carpenter, and the computers. From helium-cooled
superconducting magnets to tungsten chamber walls to supercomputers
that can calculate how the plasma will behave far more accurately and
quickly than ever before, the pieces are all there, waiting for the
politicians to sign off the cheques and shake hands.

Sorry, by the way, if you thought that solving the world's energy
problems was about something as trivial as science. As might be
clear, it's really all politics.

And finally: fusion scientists have managed to get all this cash
without enlisting Sir Bob Geldof or getting Pink Floyd to reform.
Imagine if they had: we'd probably all have fusion-powered cars by
now.


---
* Origin: [adminz] tech, security, support (192:168/0.2)

generated by msg2page 0.06 on Jul 21, 2006 at 19:03:47

 search:
this site only