Fusion catches fire
Posted: Tuesday, March 31, 2009 6:46 PM by Alan Boyle
LLNL
Technicians check a positioner inside the target chamber at the National Ignition
Facility in California. A tiny capsule containing fusion fuel would be placed at the
very end of the pencil-shaped positioner, then blasted by 192 laser beams.
|
All of a sudden, nuclear fusion is becoming an energy buzzword instead of an energy joke: One route to fusion is being hailed as having the potential to become a "holy cow game-changer," another mainstream method is getting a multimillion-dollar boost, and a dark-horse candidate is stealthily moving forward as well. Heck, even cold fusion is back in the game.
So what's behind the seemingly sudden interest?
Part of the buzz is dictated by the calendar. After 12 years of construction, the world's most powerful laser is finally finished at the National Ignition Facility in California, and VIPs are getting a look at some of the best that Big Science has to offer in fusion energy research.
But part of it is dictated by the hard times we're living in, said Richard Nebel, who heads a team looking at an unconventional kind of fusion technology. "These can be the times when innovation can really take hold," he told me today.
The way Nebel sees it, tough times can spur people to look for unconventional solutions to society's challenges - for example, how to develop cleaner, cheaper, more abundant sources of energy. Biofuels (including algae), wind, wave, geothermal and solar power are all part of the mix, along with better batteries and greater fuel efficiency.
There's a place for safer nuclear power as well, involving fission as well as future fusion - or maybe even fission-fusion hybrids. Here's a quick rundown of the latest developments:
Laser fusion
The $3.5 billion National Ignition Facility has been 12 years in the making, but today the Energy Department announced that the super-laser-blaster is fully operational and ready for business. The department has emphasized the facility's function as an H-bomb simulator, probably because that's its most down-to-earth application. However, a lot of researchers and onlookers are hoping that the NIF can provide a realistic route to commercial fusion power.
LLNL |
Click for video:
The National Ignition
Facility explains "the
power of light."
|
The NIF's array of 192 pulsed lasers are designed to blast pellets of deuterium-tritium fuel so intensely that they ignite in a fusion reaction. Earlier this month, NIF's operators reported that they delivered more than a megajoule of laser energy to the target chamber's focus point - which should be enough to get nuclear fusion started.
The prospect of creating a controlled fusion reaction is what led New York Times columnist Thomas Friedman to write that the research planned for NIF might be a "holy cow game-changer" in the energy quest. If the technique actually works, a $10 billion pilot power plant could be built to prove that "any local power utility could have its own miniature sun - on a commercial basis," Friedman said.
And if not? "At the pace we're going with the technologies we have, without some game-changers, climate change is going to have its way with us," he wrote.
Tokamak fusion
The other Big Science path to fusion leads through France, where the $13 billion ITER fusion research plant is under construction. ITER, due for startup in 2016, is an international effort that is based on magnetic-confinement technology. The fusion reaction would be contained within a highly shielded, doughnut-shaped chamber known as a tokamak.
A year ago, U.S. participation in ITER was essentially put on hold due to the budgetary battles between Congress and the Bush administration. There was a risk that U.S. firms would be locked out from participation in the project - but that scenario was averted when the Energy Department restored ITER's funding just in the nick of time.
The omnibus spending bill for the remainder of this fiscal year, which was signed into law three weeks ago, includes $124 million for the U.S. involvement in ITER. Thom Mason, the director of Tennessee's Oak Ridge National Laboratory, told the Knoxville News Sentinel's Frank Munger that the U.S. ITER effort had been "running on fumes" for the past few months.
"So, this will really help the morale and get people moving," he said.
The big priority now is to arrange for the purchase of U.S.-built hardware that the federal government has promised to contribute to the ITER reactor. That should have a "good economic impact in terms of employment," Mason said.
Fission-fusion hybrids
Some researchers say the fusion process could be paired up with the fission process to reduce the amount of waste left behind by conventional nuclear reactors.
The classic hybrid concept - known as Laser Inertial Fusion-Fission Energy, or LIFE - was developed by NIF researchers: They suggested that a laser-sparked fusion reaction could supply extra neutrons inside a fission reactor. That power boost would burn up radioactive leftovers that otherwise would have to be stored or reprocessed.
More recently, physicists at the University of Texas at Austin proposed a similar hybrid technique that would employ a fusion tokamak rather than a laser-blaster. The technique was touted by Forbes magazine's Jonathan Fahey as a "Texas Smoosh 'Em." (Fahey also looked at the LIFE concept.)
The idea's boosters say going with hybrid reactors would reduce the need for long-term waste repositories such as the one that had been planned for Yucca Mountain in Nevada. It looks as if the Obama administration is pulling the plug on the plans for Yucca Mountain, so
any strategy that cuts down on the nuclear waste problem would be warmly welcomed.
However, it's not yet clear whether the fusion-fission hybrid concept is workable. Over at the Atomic Insights blog, Rod Adams is skeptical about NIF in general and hybrid nuclear power in particular. "Fission works; fusion is a complex hallucination," Adams writes.
Polywell fusion
If fusion is a hallucination, the wildest part of the vision would have to be the project that Nebel and his colleagues are working on at EMC2 Fusion Development Corp. in New Mexico. They're following up on preliminary indications that a relatively low-budget, high-voltage gizmo known as a Polywell fusion device could produce more energy than it consumes - that is, if the gizmo is scaled up to the appropriate size.
Late last year, Nebel's team sent a report about their experiments to their funders at the U.S. Navy. The results were encouraging enough that the Navy is providing the money for follow-up work through the end of this year.
Nebel told me the interim funding was meant to "keep us alive until they figure out what they want to do." Although he was reluctant to go into the details, progress reports posted on the Talk-Polywell discussion forum and the Dean's World blog indicate that the device's design is being tweaked to improve its performance.
"We've been trying to clean up some of the things we know we can do better," Nebel said.
Nebel has long hoped that the technology could be ramped up to create commercially viable fusion reactors - which would cost way less than $10 billion each, by the way. He is still hopeful. "We think that we should be able to go forward with this," he said.
However, Nebel is also reluctant to overpromise. That might not be a bad thing, considering that so many people involved in the fusion quest have been promising so much for so long. The most Nebel will say is that the studies - and the discussions with potential funders - are continuing.
