Wed 28 Oct 2009
We need more energy! That urgent message kept bursting through a panel discussion at Stevens on October 14 on “Fossil Fuels in the Year 2050.” The panel featured Paul Winstanley, Director of Energy Initiatives here at Stevens, as well as experts from the Department of Energy, Penn State and Shell Oil. The discussion, sponsored by Stevens, Discover and Shell, was moderated by Corey Powell, editor of Discover magazine and an old buddy.
Oil and other fossil fuels can’t last forever, these experts agreed. We need other sources of energy. But what? The panel brought up the usual alternatives–solar, wind, biofuels, nuclear fission–as well as one not mentioned much lately: fusion. You all know the difference between fission and fusion, right? In fission a heavy atom, such as uranium or plutonium, splits apart, releasing energy that triggers more fission and hence a chain reaction. The bombs that destroyed Hiroshima and Nagasaki were fission bombs. All the world’s nuclear-energy reactors–like Indian Point, just a few miles south of where I live on the Hudson River—exploit fission.
In fusion, two light atoms, such as hydrogen, slam together, forming a heavier atom and releasing energy. Fusion is a much, much more potent source of energy than fission. The sun is a giant fusion reactor, which means in a sense that we are already living in a fusion-energy world. But so far the only “successful” fusion technology is the so-called hydrogen or thermonuclear bomb, which makes the fission bombs that we dropped on Japan look like firecrackers.
For more than 50 years, physicists have sought to harness fusion to create energy-producing reactors, which in principle could solve all our energy needs. What is the status of fusion research? Can it help us kick our addiction to fossil fuels? True believers keep promising that fusion will solve all our problems, delivering energy “too cheap to meter,” to use one famous pitch. But so far, no fusion reactor has come close to producing more energy than it consumes. Skeptics say it’s time to pull the plug on fusion research, which is always promising… and promising, and promising.
If you want the real scoop on fusion, come to the next talk of the Center for Science Writings, to be held Wednesday, October 28–that’s today!–at 4 p.m., in the Babbio Center, Room 122. The speaker will be Charles Seife, a professor of journalism at NYU and author of several acclaimed books on physics. His latest, “Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking,” Bethe, Edward Teller—the real-life model for crazy Dr. Strangelove–and other titans of twentieth century physics. Maybe Seife will help us decide whether fusion energy is more moonshine than sunshine.
October 29th, 2009 at 4:01 am
Before you go to this next event try doing a little RESEARCH ! The fifty year story of fusion energy always promising but never quite delivering is down to two things… 1. A lack of realisation by scientists of how big the challenge really is (the optimist who made the statement about energy being too cheap to meter regretted it as soon as he said the words) and 2. Lack of funding by authorities who also didn’t realise the scale of the challenge and, (being politicians and bureaucrats, whose vision extends only to the next election or pay packet), thought they could get away with the cheap and easy answer, carrying on with fossil fuels and adding a bit of fission on the top. For those who bother to do the research, you will see that there is another much more promising (but less trumpeted) route to fusion, using very large lasers to compress the energy needed to start the reaction… and it’s coming soon ! The National Ignition Facility in California is approaching proof of principle for laser-driven fusion with “energy break-even” (more energy from the reaction than is required to start it).. most likely in the next two to three years. When that is done, the sceptics will have to find something else to be sceptical about. The European HiPER Project is gearing up to take forward that proof of principle to build a test bed reactor, which in turn will leads to the prototype fusion energy plant, capable of delivering electricity at industrial levels. Seife doesn’t know the whole story… find out for yourself. Google NIF then Google HiPER !
There’s one clear indicator that laser fusion is making real progress… the executives in the other fusion approach are starting to criticise it in the only way they can… saying it’s just nuclear weapons research in disguise. The truth is that they are scared of losing research funding for their own projects. The world needs both approaches. Fusion energy development is the ultimate example of “swords beaten into ploughshares”… the most natural form of energy release on the grand scale is fusion. Just look at the sun and every other star in the sky. So far we have only mastered it for weapons, but the same properties of atoms can give us a really efficient power source, beside which every other method pales into insignificance. We need to get that research done before the lights start going out… which will be really soon … at the reckless rate we now burn energy !
October 30th, 2009 at 8:25 am
John,
To get any fusion to work using magnetic fields is not stable or safe; it’s like compressing an orange with your hands. Juice is liable to squirt out. To get a useful (gigawatt range) energy output to compete with conventional fission or other power plants (exceeding the energy you’re supplying as input to the electromagnets to hold the plasma in place, and to the lasers or whatever heats the hydrogen isotopes into plasma), you need to to use a highly unstable magnetic field system to contain a DANGEROUSLY large amounts of fusion fuel.
Reduce the amount to safe quantities, and it’s a failure compared to existing power plants. It might not even produce enough power to run its own electromagnets and lasers! So you need to have a nuclear fireball comfined by magnetic fields. Any power loss or failure of the electromagnets, and your “clean” energy source turns into Hiroshima.
Worse still, to get fusion practical at all, you need high cross-section fusion reactions such as deuterium + tritium -> helium-4 + neutron + 17.6 MeV energy. In this reaction, conservation of momentum means that the neutron (which has 20% of the mass of the products) takes 80% of the energy, so it is a 14.1 MeV neutron. Very penetrating, and if you try to stop it with a dense shield, you get neutron induced activity (in steel this will be things like iron-55, cobalt-60, and such like, with long half lives and radioactivity hazards).
How do you convert that 80% of the fusion energy which comes off as neutrons into useful energy? In fission, most of the energy does not come off as neutrons (which have a mean energy of only 1 MeV before being moderated down to 0.025 eV), but as the kinetic energy of the heavy fission fragments. This is easily converted into heat by boiling water.
14.1 MeV neutrons carrying 80% of fusion energy present more of a problem to extract energy from. A thick steel or metal barrier will scatter them and absorb energy, but how do you then get electricity? If you can heat water, as in fission reactors, the steam drives a turbine. You can’t do that so easily with fusion neutrons!
In the H-bomb, the 14.1 MeV neutrons are captured in a U-238 jacket where they cause fission and neutron capture which produces neptunium-239 to add to the useful energy release. But if you did that with a “clean” nuclear reactor, you’d be making it even more dirty, and turning it into a fusion-fission device. The whole thing is a propaganda hype/spin fiasco going back to Eisenhower’s “Atoms for Peace” politics. There’s no science, the people who work on it are charlatans who suck in money for decades knowing (happily) that it will never be feasible.
October 30th, 2009 at 8:28 am
(P.S.: For an example of the problems of electromagnets, just look at the delays they have caused the LHC at CERN! To magnetically contain fusion plasma emitting gigawatts of energy will extremely dangerous. Any solder joint which melts in a magnet will allow the plasma to escape and the thing will blow up!)
October 30th, 2009 at 9:56 am
I suspect that the breakthrough for fusion will occur when researchers realize that they can not only use high energy lasers to heat the plasma to critical temperature, but they can control the reaction and extract energy using “cooling” lasers.
What a “cooling” laser basically does is remove energy from the area illuminated by a laser beam. Rather magically, this energy appears at the laser emitting device itself, where said energy is much easier to harvest because the emitting devices can be at quite a distance from the fusion core.
October 31st, 2009 at 11:04 am
A “cooling laser” which safely extracts gigawatts neutron energy from fusion plasma in an economic clean reactor will not be “rather magical”, but totally magical.