A microbial fuel cell taps into the energy that soil microbes generate when they break down organic matter. Literally, this is energy from dirt: no special microbes or conditions are needed other than enough moisture for the bugs to do their work.
Essentially all you do is dig a hole, layer an anode, some soil, sand and a cathode — and connect the anode and cathode to a circuit board to charge a battery that can power an LED (light emitting diode) light, run a radio or charge a mobile phone.
In Africa, 74% of the population is off the electric grid. LebÃ´nÃª‘s website describes the problem:x3
… Imagine a village at night in which students are walking to distant highways to study under streetlights, where small merchants are investing half of their resources to pay for kerosene lighting to run their operations, and where emergency health workers, if operating at all, are trying to stitch up wounds and perform surgeries by candlelight. …
A LebÃ´nÃª MFC electric unit can replace a kerosene lamp for $10 and a cubic meter of dirt. Units can be easily linked to multiply energy output. The underground system works through day and night, in wind and calm, is rugged, simple, lasts for years, and can be made in the region where it is used. This month, LebÃ´nÃª won a $200,000 World Bank grant in the Lighting Africa competition held in Accra, Ghana. LebÃ´nÃª will use that money as it begins field studies in the foothills of Kilimanjaro in July. It plans a large-scale product rollout in Tanzania for 2009.
Video from floor of Accra conference; Interview with Hugo Van Vuuren starts at 1:00