Tuesday, February 26, 2008

Our Nano-future, Now

I recall reading K. Eric Drexler's landmark book on nanotechnology, "Engines of Creation," sometime in the late 1980s or early 1990s and being bowled over by the potential it represented, including science-fictional possibilities of being able to build objects and devices essentially one atom at a time. As was the case with the first stages of biotechnology, no one could predict the kind of practical fruits that such an entirely new area of science would yield, or how quickly. Lately, I've been struck by the appearance of multiple applications of nanotechnology to energy, at least on a laboratory scale. Whether any of these ultimately becomes commercial may matter less than the signal this sends about how rapidly nanotechnology is maturing and being integrated into technologists' toolkits.

A decade ago, the most promising energy-related nanotechnology research appeared to be the use of carbon nanotubes for hydrogen storage. That work is still progressing, and if hydrogen becomes a mainstream transportation fuel, nanotubes ought to give pressurized storage and metal hydrides some stiff competitions. In the meantime, however, a number of other lines of nanotech R&D are producing interesting results with possible energy applications. These discoveries run the gamut from the merely intriguing to the potentially transformational. Here are some of the recent announcements:
  • Silicon nano-wires that dramatically increase the energy storage capacity of Lithium-ion batteries, while also reducing recharging times. If they work as expected, we might be able to bypass plug-in hybrid cars (PHEVs) and go straight to long-range electric vehicles, or build practical PHEVs with very small onboard generators.
  • Nanowire solar cells that allow for greatly increased photovoltaic efficiency at little or no extra cost. That would reduce the area necessary to generate a desired quantity of power, while incidentally reducing the cost of the non-PV components of a solar power installation.
  • Nanowire fabrics that generate electricity from the energy of the wearer's motion. Initially these might provide power for medical devices or sensors, but eventually could recharge your phone or iPod--or even make entirely unanticipated forms of consumer electronics possible.
  • Nanoparticles that enhance the electrolysis of water for hydrogen production. Reducing the energy losses from electrolysis could make truly zero-emission hydrogen from renewable electricity more competitive with hydrogen produced from natural gas--the main source today--and it might also make reversible fuel cells an effective solution for matching the intermittent output of wind and solar power to grid demand patterns.

As exciting as all this is, it's also worth noting that we don't yet understand all the risks entailed in working at nano-scale. We needn't worry about the possibility of "self-replicating assemblers"--the genesis of the infamous "Gray Goo Problem"--for some time. Nevertheless, nano-materials, objects with at least one dimension of approximately one-billionth of a meter in length or less, may pose health risks, because biological life on earth never evolved to deal with them. As with the development of any new industrial chemical, the long-term environmental impacts of these materials must be addressed in tandem with their applications. A bit of caution is in order, though it still appears that a field that not long ago seemed highly speculative could have an impact on the problems of energy security and climate change in the near future.

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