When Robert Goldston, director of the Princeton Plasma Physics Laboratory and professor of astrophysical sciences at Princeton University, left for Harvard in 1968, he was unsure whether to pursue psychology or physics, and this indecision persisted until a summer hike in the Green Mountains in Vermont between his sophomore and junior years.

As Goldston stared down at Stowe Village, he noticed the smoke hovering above the rooftops and this energy byproduct got him thinking more broadly about energy and its role in human life. “The wonderful thing about human beings is that they take in energy and create beauty,” he remembers thinking. “Mozart eats a peanut-butter sandwich for lunch, and what he does with the energy is create a concerto.”

Fine and good, but there was more to Goldston’s insight on the mountain, one that would be life changing for him. “The trick,” he thought, “is to do that without all the smoke that comes out of Stowe Village.” And then he asked himself, “Is there a way to create more energy without polluting the world?”

When Goldston got home, he hunkered down and taught himself all of freshman physics and some of sophomore physics. Luckily he had kept up with the math he needed, and he managed to graduate on time in 1972 with a physics degree. He got into graduate school at Princeton, “the mecca of fusion science,” where he earned a doctorate in astrophysics in 1977, with a focus on the physics of plasmas of hot gases. Recently his son, Josh, also received a doctorate in astrophysics but, jokes Goldston, “Josh is studying real stars.” Actually Goldston’s father was also in the energy business, as a lawyer and businessman involved with Boston Gas Company and the coal industry; his mother, though, was a social worker

Goldston will speak on “Fusion Energy and Climate Change,” on Wednesday, July 16, at 7:30 a.m. for the Princeton Regional Chamber of Commerce at the Nassau Club, 6 Mercer Street in Princeton. Cost: $30. To register, go to www.princetonchamber.org.

The plasma physicists who work on creating energy from nuclear fusion are on what might be termed the long-term planning committee on climate change. Although the technology has made huge progress since its inception in the early 1950s after Lyman Spitzer got an inspiration on a ski lift in Aspen about how to use a magnetic field to confine a plasma, projections of globally significant energy production from fusion are probably a half-century away. But Goldston and his colleagues are hopeful that after nearer-term technologies have lowered the infusion of carbon dioxide into the atmosphere, fusion will produce sufficient clean energy to help complete the job.

Goldston talks about a 2004 article in Science magazine by Princeton’s Steve Pacala and Rob Socolow that looks at a favorable scenario where the world manages to level off or slightly lower carbon dioxide emissions over the next 50 years. In this scenario the authors of the article imagine that each of several near-term technologies and their consequences — improved efficiency; electricity from natural gas; a reduced rate of deforestation; sequestering carbon dioxide by burying it; nuclear fission; and wind, solar, and biomass — will manage to bring carbon emissions down by about one gigaton, a billion tons, per year.

Not implementing these shorter-term technologies would mean continuing business as usual, bringing with it a huge growth in yearly carbon dioxide emissions that will not be good for the health of this planet. Extrapolating from emissions in 2004, which were seven gigatons of carbon dioxide into the atmosphere, Pacala and Socolow suggest that by 2054 emissions would reach 14 gigatons a year and by 2104, 21 gigatons a year.

The shorter-term technologies are critical but will not deliver sufficient improvement: Improved efficiency is by definition only a percentage improvement over the present; natural gas is running out and is not cheap; forests are not infinite; the effects of burying carbon dioxide are unknown; nuclear fission on a very large scale carries with it the danger of nuclear proliferation; and wind and solar can likely supply, tops, 20 percent of the electrical grid because the power they deliver is not constant.

Even if the shorter-term technologies are fully effective, they will only maintain emissions at the current level. Slowly but surely more players are joining the polluting giants as development in huge third-world economies like China, India, and others is bringing on line new vehicles and factories daily.

Even if the world community manages to implement these shorter-term technologies and keep the yearly emissions level flat, however, the level of carbon dioxide in the atmosphere would rise, because we would be adding more carbon, with little leaving the atmosphere.

The United Nations Foundation Scientific Expert Group on Climate Change and Sustainable Development in fact had this recommendation: “The needed prompt and sharp departures from the ‘business-as-usual’ trajectory must lead to an early leveling off of those emissions at a figure not much larger than today’s, followed by a decline to approximately one-quarter to one-third of today’s emissions by the end of the century.”

Even with a goal of 500 parts per million of carbon dioxide — which is a little below two times the preindustrial level of carbon dioxide and still thought by some to be risky — Socolow indicated the necessity for a 90-percent reduction of carbon dioxide emissions in comparison with business as usual by the end of the century. The International Panel on Climate Change indicates that we need to cut back carbon dioxide emissions nine times more per year from 2030 to 2100 than from 2000 to 2030.

Goldston suggests that three major cost-effective options exist for baseload electric power in the long term that reduce carbon emissions. The first is a coal-burning plant with carbon sequestration, or burial, nearby. Using this well-developed technology, the carbon dioxide is liquefied and pumped underground, into saline aquifers. During the lifetime of one plant, about a third of a gigaton of carbon dioxide would be sequestered under about 100 square miles.

But the technology also has some serious potential drawbacks. If the carbon dioxide leaks out too quickly, it will not solve the problem, and it can be dangerous. Furthermore the sequestration will drive a certain number of small earthquakes and potentially even larger ones. Finally, there is an issue that people may not want carbon dioxide under their backyards.

Nonetheless Goldston thinks that the technology is promising. “My position is that we need to dig into the issue, try it at full scale in unpopulated places, and see if it is a viable and safe thing to do.”

A second long-term energy possibility is using breeder reactors to produce plutonium while generating electricity using nuclear fission. Wide implementation of this alternative would require production in the range of 2 million kilograms of plutonium a year. The problem with this technology is that creating an atomic bomb requires only six kilograms of plutonium. “If you have the whole energy economy based on this technology,” says Goldston, “it’s not hard to just siphon a little off on the side without it being detected.”

The technology can, however, be cost-competitive with the other long-term alternatives, and there are viable ideas for isolating the nuclear waste. But before putting this technology into high gear, we must find a way to prevent it from also fueling nuclear proliferation.

Fusion is the third long-term alternative. Fusion takes place when two types of hydrogen are heated to very high temperatures, to the point where their positive charges no longer repel each other so much that they always bounce away from one another. Instead they fuse, creating a helium nucleus that provides heat to continue fueling the reaction, hydrogen that can be used to power cars, and energy for electricity.

In Goldston’s years in the field, he has seen significant advances. “When I was a grad student, we produced a tenth of a watt for a hundredth of a second — one thousandth of a joule of energy,” he says. “Relatively recently in the U.S. and Europe, we made 10 million watts for about one second.” And the big international project that will be turned on in 2018 is expected to produce 10,000 times more energy, thereby demonstrating the scientific and technical feasibility of fusion.

Goldston offers a number of reasons why fusion might be the perfect fuel to make a dint in atmospheric carbon dioxide over the longer-term horizon, where massive reductions in emissions will be necessary:

Fusion fuel is inexpensive and widely available. Millions of years worth of deuterium fuel is available, the tritium isotope is a byproduct of some Canadian reactors, and the neutron byproduct of the fusion reaction can itself be used to produce more tritium. Because these fuels are readily available, the kinds of competition for energy resources that can cause geopolitical instability are absent in the fusion arena.

Since fusion is a relatively clean technology, it produces neither acid rain nor carbon dioxide and hence reduces pollution and global climate change.

When compared to nuclear fission, fusion is a lot safer. First of all, it can’t have a runaway reaction as happened in Chernobyl where two years of fuel began to burn in a fraction of a second. “A fusion reactor might have 30 seconds of fuel,” says Goldston, “and if it all burns at once, it makes a pop sound; it doesn’t blow up the power plant.”

Similarly a fusion reactor will not cause a meltdown, as happened at Three Mile Island.

Fusion creates relatively short-lived radioactive material. To lower the radioactivity level of fusion waste to about the level from an equivalent coal plant, which has declared to be below regulatory concern, takes only 100 years, as compared to a million years for waste produced by fission. As a result it does not need a “Yucca Mountain” waste dump solution.

Fusion is also a steady power source that can be located near markets, without requiring significant energy storage, the sequestering of carbon dioxide, long-distance transmission, or significant land use.

So where’s the rub? In Goldston’s view, there are still scientific and technical hurdles, but a large factor is society’s degree of commitment. “The size of the investment and time scale are prohibitive for private corporations,” says Goldston. Hence the only realistic source for this kind of long-term social investment is the government.

Goldston notes that $30 billion was originally authorized by the Fusion Engineering Act of 1980 but about one-third that amount was appropriated over the next 20 years. Unfortunately the legislation occurred when people were eager for new forms of energy. But in the 1980s and 1990s when oil was dirt cheap, funds dried up, and funding for fusion is still about $18 billion short of the initial authorization. Even today the United States government has not fully committed to fusion funding, and recently a major endeavor by the Princeton Plasma Physics Laboratory, which proved to be more expensive than had been anticipated, has been halted by the Department of Energy.

Yet fusion is an area of immense promise. If fusion were to grow at the rate that fission grew worldwide before Chernobyl and Three Mile Island, suggests Goldston, it could satisfy half of the world’s electricity needs by the end of the century. Goldston remains hopeful that fusion will be an important tool in the second half of the 21st century: “If we want a limited amount of carbon dioxide, we’d better have some major new energy sources that don’t emit carbon.”

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