A Dirt-Bag Fuel Cell

A startup that is striving to bring energy to countries that lack reliable power has developed a remarkably simple new microbial fuel-cell design: grain bags, stuffed with metal and dirt. Lebônê, a startup based at Harvard University, has already shown how to make fuel cells from buckets full of wastewater, with a graphite cloth as the anode and chicken wire as the cathode. In this setup, bacteria extract electrons from organic waste at the anode to generate small amounts of power–enough to charge, say, a flashlight or cell phone.

A contact at the company tells me that the bags work pretty much the same way, but they should be even easier to make and more portable than the bucket design. What’s more, owners can bury the bags in the yard, so that they are undisturbed and out of the way. They can even link several of the bags together–in series or in parallel–to increase the voltage or the electrode area, respectively.

The bags are fairly ubiquitous across Africa, according to the startup. “They’re very familiar to the people there, so it’s a natural material to use for something that we want to get widespread acceptance for,” says CTO Aviva Pressner. The team is still testing the best materials to use, and it reports that a graphite anode and aluminum cathode combination works well. With funding from a World Bank grant, Lebônê plans to deploy several hundred bags in Namibia this summer and thousands more in 2010.