Thursday, February 28, 2013

Why I'm No Longer Betting on Fusion

I am of an age to have been reading science fiction stories that included fusion reactors providing electricity for most of 50 years now.  For much of that, I've also read non-specialist technical publications about progress towards that goal.  One piece of black humor that has emerged over that period is the definition of a new basic constant in physics: the time remaining before commercial fusion power is ready is always 30 years.  There is little reason to believe that the constant is changing.

ITER is a multi-country research effort broadly believed to be the project with the best chance of delivering commercial fusion [1].  At the present time, the schedule calls for first plasma in 2020 and first deuterium-tritium fusion in 2027.  ITER itself won't be used to generate electricity.  The project's schedule calls for the DEMO system, ITER's successor, to begin generating power in 2033.  After an indeterminate period of DEMO operation, PROTO can be designed and built -- the prototype for a commercial reactor.  Given all of that, 2043 seems like the nearest potential date -- still 30 years out.  There are game-breakers in the project as well; for example, one of the purposes of ITER is to determine if the structural materials actually hold up under the high neutron flux that will be produced.

The problem is, in my mind, is that we (taking my usual parochial view of "we" to mean the US) need to take actions sooner than that.  I believe that the US, and the heavily-populated eastern portions of the US in particular, face an electricity crisis within the next 30 years.

In 2011, states in the US Eastern Interconnect accounted for about 71% of all US generation.  In addition, the Eastern Interconnect is much more dependent on nuclear and coal than the other parts of the country: about 70% of the Eastern Interconnect's generation is from coal and nuclear; for the Texas Interconnect about 45%; and for the Western Interconnect about 38% [2].  That 70% in the Eastern consists of 23% from aging nuclear reactors and 47% from coal.  Over the next 30 years, the license extensions for the nuclear plants will expire.  At least IMO, no one in their right mind is going to grant further extensions to those plants.  Too many of them are aging badly, and spent fuel storage will become an increasingly difficult problem.  Popular opinion seems to be trending towards forcing coal-fired plants to clean up their act.  Not just the controversial CO2 requirements, but the much less controversial emissions of sulfur- and nitrous-oxides, heavy metals, and fine particulates.  In many cases, that will translate into replacement systems, not upgrades of existing plants.

So the first problem is that if the US, and the Eastern Interconnect in particular, is to maintain its generating capacity, it appears that it must undertake a substantial capital program over the next 30 years, before fusion is going to be commercially ready.  Companies are not going to undertake another spending program before they are ready to begin retiring those relatively-new non-fusion plants.  That introduces one set of delays.  The second problem is that advanced tech can be very much a "use it or lose it" proposition.  In 1969, the Saturn V rocket could lift 118,000 kg to low earth orbit.  We used that lift capability to put men on the moon.  Today, the largest rocket available globally can only lift a small fraction of that much to LEO.  New systems that would match the Saturn V are on the drawing boards, but no one looks for them to be ready before 2030.  Fusion could easily turn into the same sort of thing: the PROTO system gets built, but falls into disuse because of the capital timing issue, and we lose the hands-on knowledge needed for broad commercial deployment.

And that's why I'm not betting on fusion as a solution.  Not because we won't eventually solve the technical problems, but because the timing and limits on available capital are going to be bad.

[1] I acknowledge that there are other programs pursuing other strategies.  ITER is the program that almost everyone thinks of when they think "fusion research".

[2] Figures are for calender year 2011, from the EIA by-state-by-source spreadsheet.  Coal usage will be down somewhat across all three regions in 2012, due to a glut of cheap natural gas.  Nuclear usage will be down in the Western in 2012 due to the San Onefre reactors being offline for most of the year.

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