An Indispensable Truth: How Fusion Power Can Save the Planet, Francis F. Chen, Springer, New York, 2011. $49.95 (433 pp.). ISBN 978-1-4419-7819-6
With An Indispensable Truth: How Fusion Power Can Save the Planet, Frank Chen has provided a sweeping perspective on fusion energy. He covers everything from climate change to plasma instabilities. On climate change and energy, the view is best from 30 000 feet: The book provides a good high-level overview of the issues at stake, but some of the details of his conclusions are not clear. On fusion plasma physics, Chen’s area of expertise, An Indispensable Truth provides an intuitive, up-close explanation of exciting recent advances and future challenges.
The book starts by reviewing the strong evidence that recent climate warming is anthropogenic, as well as the much weaker evidence that the planet may be nearing a tipping point, such as might lead to the slowing of the Gulf Stream or a massive rise in sea level. However, Chen’s analysis doesn’t quite get to which actions we should be taking now. In my opinion, lacking the global will to pay today for strong reductions in carbon emissions, we must nevertheless strive to increase energy efficiency, deploy the most cost-effective low-carbon technologies, and perform the R&D for attractive future low-carbon options such as fusion. As the R/P (reserves divided by production) figures in the book show, fossil fuels are running out, so we will need new energy sources soon in any case.
Chen provides fascinating reviews of carbon-sequestration and renewable-energy technologies, but he is somewhat pessimistic on their application. He seems to conclude that the development of sequestration technology will take too long, and he maintains that renewables, due to their intermittency, cannot provide what he calls the world’s “backbone power.” But certainly we must do the R&D to understand if and where we can bury carbon safely, and energy and climate models generally project that something in the range of 30% of the world’s electricity will come from renewables by 2100, “backbone” or not.
In a short section on nuclear fission, Chen is more bullish; but, in my opinion, he underestimates the safety and proliferation risks. The meltdowns at the Fukushima Dai-ichi nuclear power plant following the Great East Japan Earthquake evidently came too late to be included, but now over 1% of the world’s commercial fission reactors have been destroyed by accidents. To put proliferation risks in perspective, consider that nuclear fission may be called upon to provide about 30% of the world’s electricity in 2100, given the limitations Chen notes on carbon sequestration—for example, the “Not Under My Back Yard” syndrome—and the intermittency of renewables (and assuming we have not developed fusion). In that scenario, fast-neutron-spectrum fission reactors could be required to reduce geological waste storage, to extend uranium resources, or both. A one-year supply of fuel stored at those reactors would hold, in sum, enough plutonium for about 1 million Nagasaki bombs.
When Chen gets to fusion—the energy solution that is the book’s “indispensable truth”—he displays his signature ability to explain plasmas intuitively, without equations. He shows how magnetic fields can contain plasmas, so long as their lines circumnavigate a toroidal confinement zone. He then shows why helical twist is needed in the field lines. He goes on to explain plasma instabilities, large and small, and even gives an explanation for why shear is needed in the helical twist to restrain the instabilities. He lays out the truly astounding advances that have been made both in the fusion performance of tokamaks, the best-developed magnetic configuration, and in the general scientific understanding of fusion plasmas. He includes intuitive explanations of such expert topics as H-mode, reversed magnetic shear, and internal transport barriers.
Chen is accurate in assessing that the greatest outstanding scientific issue for the tokamak is so-called disruption, where the confined plasma is suddenly lost to the chamber wall, possibly causing localized damage that would require a shutdown to repair. He correctly identifies the closely related stellarator configuration as the solution if disruptions prove too touchy to control in the tokamak. The book also outlines the outstanding materials-engineering challenge. ITER, a major international fusion project under construction in France by China, Europe, India, Japan, Russia, South Korea, and the US, will demonstrate that fusion reactions can be energetically self-sustaining. The big remaining challenge will be to show how to manage the success that will come in the form of high power densities of both plasma and neutrons impinging on the first material surfaces.
Chen gives little credence to inertial confinement fusion, which is based on repetitive fusion microexplosions triggered by intense beams of energy, such as can be provided by lasers. Contrary to Chen’s analysis, if the National Ignition Facility based at Lawrence Livermore National Laboratory produces high fusion gain from a laser striking a target that contains a deuterium–tritium capsule, I imagine that the fusion research community will want to further examine how this might be developed into a fusion-energy system. (A committee at the National Academies is reviewing that issue now.) There are short sections on cold fusion and bubble fusion, two ephemera that have proven not to be reproducible. Also discussed are future options for fusion fuels that do not produce neutrons.
The book concludes that leadership in fusion research has slipped away from the US to Europe and Asia. But the US could retake a leading position by addressing some of the outstanding materials engineering challenges or by developing advanced stellarators. Chen contrasts the present cost of magnetic fusion research—roughly $400 million per year—with the Iraq war at $100 billion per year and with NASA’s budget. (Somehow NASA’s annual budget is pegged at $1.9 billion rather than $19 billion. A number of such errors in the book suggest a too-rapid final edit.) It is clear that fusion and other promising energy R&D projects—particularly when their costs are compared with the correct NASA budget—merit higher priority.
An Indispensable Truth provides an exciting whirlwind tour of energy issues and technologies, with particular insight into fusion. Chen is correct to emphasize the tremendous progress that has been made in fusion research. ITER will produce hundreds of millions of watts of thermal energy from fusion, for periods of up to an hour. However, it remains for the world, and in particular for the US, to decide if we will develop fusion into a practical energy source. We will need it.
