Barrett H. Ripin, associate executive officer of The American Physical Society, offers this reply:
"Actually, fusion research has made remarkable progress in recent years. There is no longer any question of its scientific feasibility: near breakeven (the state at which the fusion power produced equals the power consumed to sustain the plasma) has been demonstrated with actual fusion fuels in Princeton's nearly 20-year-old Tokamak Fusion Test Reactor (TFTR). Dramatically improved operating regimes have recently been discovered that may form the basis of a practical energy reactor. An alternate approach, known as inertial confinement fusion, has also made substantial progress. Inertial confinement fusion is poised to demonstrate better than break-even gains at the turn of the century. The clear key to this progress has been advances in understanding the scientific underpinnings of plasmas and of fusion science. In the process, several billion-dollar-per-year applications of plasmas have emerged.
"The questions at hand now are really: Will fusion energy become practical and economically feasible? Is society willing to make the necessary investment to find out if the answer is yes?
"When fusion research began in earnest 30 years ago, people simply did not appreciate the complexity and subtlety of the science of plasmas, and the concomitant depth of understanding that would be needed to make controlled fusion work. Scientists also vastly underestimated the engineering requirements and constraints--a result both of naivete and unknown scientific hurdles. And it is natural that the closer one gets to the goal of practical energy, the longer each next step takes. The experimental devices grow larger and more expensive as one approaches a commercially viable fusion reactor.
"Is it worth continuing fusion development? If scientists conclude that the burning of fossil fuels is inducing unacceptable global climate change, then we have a limited number of alternatives to turn to: solar-based sources (photovoltaics, ocean, wind, etc.), nuclear fission and fusion. Solar-based sources will be increasingly important in niches but can not supply humanity's bulk power demands, particularly if worldwide standards of living continue to rise. Nuclear fission could fill the gap, but it has well-known disadvantages.
"So the question really becomes: Can we afford to take the risk not to vigorously pursue fusion? One new power plant costs between $1 billion and $10 billion these days; a new generation of power plants would total about $10 trillion! Is fusion research funding of around a billion dollars per year for even 50 more years a reasonable gamble? It is to me."
Charles C. Baker, associate director for fusion at the School of Engineering at the University of California, San Diego, and the International Thermonuclear Experimental Reactor (ITER) U.S. Home Team Leader, adds his views:
"Thank you for giving me the opportunity to respond to this question. First, let me state that I disagree with the premise of the question. Research in magnetic-confinement fusion has produced excellent results. In the past 15 years, research in the U.S. and other countries has increased by 10,000,000 times the fusion power level produced in experiments, and we have now achieved production of 10 megawatts of fusion power on the Tokamak Fusion Test Reactor at Princeton. (A tokamak is a kind of magnetic donut that has proven to be a particularly stable way to confine the extremely hot plasma needed to achieve fusion.) This dramatic progress has been accomplished through investments made by the U.S., Europe, and Japan during the 1970s on a new, more powerful class of tokamak experiment.
"The next step in power reactor performance levels, at which the plasma is capable of ignition and plasma 'burn' (wherein most of the heating energy comes from the fusion reactions), again requires a new, more powerful experimental device. The U.S. tried to proceed with a next-step burning plasma experiment in the 1980s, but was unable to obtain congressional funding. The U.S., Europe, Japan and Russia are now collaborating on the design and R&D work for a project called the International Thermonuclear Experimental Reactor. ITER is designed to achieve plasma ignition and long-pulse burn. It will also demonstrate the technology required for the core of a fusion power plant and the systems needed for extracting power from the device. This six-year collaboration, called the Engineering Design Activities, began in 1992, and exploratory discussions are now underway concerning cost-shared, international construction of this device. Such an engineering test reactor is required by all parties for progress toward practical fusion energy, so cost sharing for this step is mutually advantageous.