Researchers force bacteria to evolve for life in a fuel cell

While a recent report from the National Academies of the Sciences concluded that conservation is the short-term key to many energy issues, work continues on alternative energy production techniques like wind, solar, biomass, and fuel cells. For mobile applications, fuel cells have quickly become the technological leader because they offer high energy density (relative to other green technologies), low weight, and generally high mechanical durability. In this month’s Biosensors and Bioelectronics, a research team from University of Massachusetts Amherst describes their work on microbial fuel cells enhanced by directed evolution.

A wide array of fuel cell technologies exist, but most fall into two catagories: solid oxide fuel cells (SOFCs) or polymer electrolyte membrane fuel cells (PEMFCs). SOFCs conduct O^2- across ceramic membranes and produce high current densities with little degradation over time. Unfortunately, the ionic conduction mechanism requires high operating temperatures—usually several hundred degrees centigrade. PEMFCs conduct either protons or hydroxyls, but suffer from low current densities and significant degredation over time. While these systems show substantial promise, there is no clear leader for most mobile applications and there is room in several niche markets for other types of fuel cells.