Wednesday, April 01, 2009

Perfect Energy

The recent start-up of the latest large-scale nuclear fusion experiment, the National Ignition Facility at the Lawrence Livermore National Laboratory, was greeted with the customary mix of fanfare and skepticism that has accompanied the quest for practical fusion power for as long as I have followed it, starting as a seriously nerdy child. MIT's Technology Review does a good job of describing the new facility, which will use high-powered lasers to attempt to create useful amounts of nuclear energy. But rather than focusing on the stupendous potential of fusion energy and whether this device might finally be the one to deliver on it, I'm more interested in what our dogged pursuit of this technology through decades of frustratingly slow progress says about our collective view of our current energy sources. How much of the search for fusion springs from its inherent value, and how much from our dissatisfaction with every other long-term energy option we possess?

The answer may lie in the generally-assumed characteristics of a successful commercial nuclear fusion reactor technology, providing cheap, reliable and concentrated energy from a fuel that is as ubiquitous as it is limitless, using a process that creates large amounts of power but essentially no harmful waste. Is that a realistic expectation, or merely the aggregated antonyms of the shortcomings of every existing energy source? Consider the alternatives:
  • Fossil fuels are finite, and their production and use release a variety of unwanted byproducts, including greenhouse gases implicated in climate change. Their reserves are also unevenly distributed, giving rise to worrying levels of rent-seeking, resource nationalism, and geopolitical instability and insecurity.
  • Wind power is intermittent, unpredictable and unsightly, requiring extensive adaptation of the power grid, ample fossil-fueled back-up, expensive energy storage or all of these to contribute reliably on a large scale.
  • Solar power is more predictable than wind but still expensive, inefficient and cyclical, delivering less than a quarter of a day's peak output even in optimum locations. It takes well over 3,000 MW of solar installations to generate the same amount of energy as one 1,000 MW coal-fired power plant.
  • Geothermal power is reliable and relatively cheap. However, the "hydrothermal" reservoirs--natural deposits of steam and very hot water--that it taps are unevenly distributed and often far from markets. Enhanced, or "dry rock" geothermal offers greater promise and flexibility, though it is still in its infancy and might also cause earthquakes.
  • Ocean power taps waves, tides or temperature gradients, offering enormous potential while sharing many of the drawbacks of wind, solar and geothermal. It is also decades behind them in development.
  • Biofuels' necessary shift away from unsustainable food-based feedstocks depends on unproven or expensive technology. Truly large-scale biofuel production entails harvesting and hauling vast quantities of bulky materials with low energy densities, raising serious questions about whether it can ever create a sufficient energy surplus for the rest of the economy. This limitation also applies to electricity generated from biomass.
  • Perhaps fusion's first cousin, fission, comes closest to its ideal, providing large amounts of cheap kWhs on demand, around the clock and with very low emissions. Unfortunately, it's hobbled by the high construction cost of new reactors and concerns about safety, security, proliferation, and waste. Some of these are legitimate while others seem overblown, but the technology is no one's free lunch.

Don't get me wrong; I have always loved big science, and nothing would please me more than if the NIF performed exactly as advertised and heralded the dawn of a new era of energy abundance. However, given the long history of drawbacks and unintended consequences from all other energy sources, it seems unrealistic to suppose that any new source, including fusion, is capable of living up to all of its pre-deployment expectations. Fusion is perfect on paper, but then so is my favorite long-term energy option, space-based solar power--until the public becomes anxious about beaming megawatts of power to earth from space, or rogue nations develop anti-satellite capabilities that could hold our orbital energy supplies hostage.

I don't know what form fusion's unexpected drawbacks will take, should the NIF testing pave the way for commercial fusion power plants a decade or two from now. I do know we need a serious debate about the sorts of trade-offs we're willing to accept from any energy source we promote as part of the solution to our dual challenges of climate change and energy insecurity. At a minimum, we must move beyond the mindset in which no current technology can compete with the presumed perfection of those that are still on the drawing board or have yet to be deployed on a scale at which their flaws might become apparent. Our future energy diet will most probably be a messy mix of "all of the above", just as our current one is. Perfect energy remains an April Fool's story.

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