Friday, October 23, 2009

Defining Sustainability

A recent article in Physics World Magazine by George Crabtree titled, "The Road to Sustainability", addresses the problem of sustainable energy production and sets out three criteria for sustainability. An energy technology must last a long time, do no harm, and leave the environment unchanged. In assessing these criteria the full life cycle of the energy process needs to be considered, including construction and disposal.

This analysis is right on target, but as the author notes, the immediacy of the problems facing us means that;
we do not have the luxury of achieving full sustainability for all of our next-generation energy technologies, we can use these definitions to select our strategic sustainability targets and track our progress toward achieving them.

The article discusses the relative merits of solar, wind, nuclear, biofuels and electric cars. For each of these, Crabtree argues, true sustainability requires significant technological advances. To achieve these, he looks to nanoscience for the answers;

Nanotubes offer versatile and promising opportunities for controlling energy conversion at the nano-scale. TiO2 nanotubes like those pictured above are inexpensive, chemically inert, photostable, provide high surface-to-volume ratio and have band gaps that support sustainable energy technologies like solar water splitting, dye-sensitized solar cells and transparent conducting electrodes. They can be prepared by a variety of electrochemical processes, doped to tune their band gaps and decorated to promote surface catalytic activity.

Crabtree has taken a "technology will save us" approach that promises much even as it relies on unknown and untested technologies. Missing from the article is any discussion of conservation, downsizing or localizing where truly significant savings can be achieved using technology that already exists.

Sustainability, then also requires an acknowledgment of the limits of growth, and that we must design our energy production and usage to fit within those limits.