Future of Fusion
A frequently discussed alternative source of energy is always the sun, that radiant mass of sizzling gases bathing our planet with light and warmth.
While hordes of scientists and engineers have been developing solar panels and pointing them skyward to capture this light and turn it into electricity, other groups have been doggedly taking a different tack. Seemingly out of the general public eye, they are trying to “recreate” a tiny bit of the sun on earth.
This process is known as nuclear fusion. Unlike its more well-know counterpart nuclear fission, which creates energy from splitting an atom, fusion is the forcible marriage of two atoms that don’t want to be together. This fusion causes the release of energy, and it is this continual process that keeps the sun and other stars “lit.” Scientists have been trying to simulate this process experimentally for more than 50 years, but the technical hurdles have seemed insurmountable.
However, within the next several years, teams of physicists and engineers employing two different ways of bringing “a little bit of the sun” to earth could report preliminary advances towards a technology that would generate electricity using water as fuel while producing little to no nuclear or other waste.
It almost seems too good to be true.
Scientists from both fusion camps told the audience at the Raleigh Grand Challenge Summit that their approaches, if brought to fruition, could conceivably usher in a new era of clean energy. The trick, and it is a big one, is how to force two nuclei that would normally repel each to fuse into one, releasing energy that can be captured and used to generate electricity. These nuclei can only be coaxed together using extremely high heat such as that found on the sun.
One approach being tested at a new facility at National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a plan to aim 192 laser beams at a fuel source the size of a peppercorn. For a billionth of a second the temperature would reach that of the sun, producing heat, which can then be converted into energy.
“We are making extraordinary progress,” said Ed Moses, NIF’s principal associate director. “We hope to perform ignition experiments this fall, and if all goes according to plan, we could have a prototype by 2020 and a commercially available facility by 2030.”
For Moses, a successful “burn” this fall would mark a symbolic milestone, since this year is the 50th anniversary of the laser’s invention.
Watch Moses' spotlight address.
The other approach, being carried out by an international consortium, involves capturing a confined plasma field swirling through a large hollow “doughnut.” Powerful supermagnets will keep the plasma circling and prevent it from touching the inner walls. Construction of this International Thermonuclear Experimental Reactor (ITER) is underway in southern France.
“This plasma recreates the wispy atmosphere of the sun’s surface,” said Ned Sauthoff, ITER’s U.S. director. “This outside edge is actually the hottest part of sun.”
The wisps Sauthoff described are like large loops shooting out from, and back into, the sun’s surface, which makes the process self-sustaining – a continual process that the ITER team is trying to reproduce.
Watch Saythoff's spotlight address.
While both of these approaches for achieving sun-like conditions on Earth have been making steady yet incremental progress, the assembled panel of experts said that it will be decades at the earliest before fusion will be a significant and reliable supplier of power.
“Fusion represents a tough engineering challenge,” said Andrew Klein, professor of nuclear energy and radiation health physics at the Oregon State University. “You would have the highest and lowest temperatures on Earth within my arm span,” he said in explaining the range of technologies necessary. He was referring to the heat within the reactor chamber and refrigeration outside controlling the temperature.
The advantages, if this and succeeding generations of engineers can get their arms around the challenges they face, are attractive and worth pursuing, the experts said.
The fuel sources for fusion energy are isotopes of hydrogen known as deuterium and tritium. The supply of these two incompatible marriage partners is practically inexhaustible. Additionally, the fusion process releases no carbon dioxide or other airborne pollutants, and the small amount of radioactive “waste” has a brief half-life.
Theoretically, the long-term promise for nuclear fusion looks bright, the scientists said, but with the following caveat: an army of dedicated scientists will be required to make the technological advances needed to make fusion energy commercially viable. The areas needing intensive work range from better understanding the basic properties of plasmas to new radiation resistant materials to the development of the next generations of lasers.
Additionally, the general public needs to be made aware of the enormity of energy challenge and to be better educated on the details of the solution. This is especially true for nuclear technology, which is not as readily understood to the lay public as burning coal or turning wind turbines.
Negative stereotypes of all things nuclear still resonate with the public, with the Three Mile Island incident, the cold fusion debacle and nuclear-gone-bad movies like “It” and “Them” in mind.
“We are terrible at communication,” Moses said.
Sauthoff added: “We (scientists) have to keep doing events like this. We must make ourselves more visible. We have to get out into public, onto television – we have a good product, we should be proud of it.”