Energy: Harnessing dirt power

Batteries powered by soil could provide electricity to millions of Africans.

It sounds like a high-school science fair project: How can you use graphite cloth, chicken wire and soil to create a battery? But it’s actually a high-stakes enterprise led by a Harvard engineering team with a very serious goal: creating a new source of power for the more than 500 million people in sub-Saharan Africa who live without access to electricity.

Called Lebônê Solutions (after the African Sotho word for “light”), the organization set out to find a source of dirt-cheap power, and they succeeded. “Literally, this is energy from dirt,” says Hugo Van Vuuren, one of the Lebônê’s founders.

The microbial fuel cells they developed use soil bacteria to create an electric charge. In the presence of water, such bacteria naturally produce free electrons as a byproduct of their metabolic growth. The cells, which are placed in canvas bags filled with dirt and buried in the ground, harness those electrons to create enough current to power LED lights, run a radio and charge mobile phones.

The Lebônê team could provide the batteries to African villages ready-made, but they want villagers to build their own to promote a sense of ownership. They hope that as the technology is refined, each household can make its own battery for a one-time cost of less than $10.

This past June, Lebônê used a $200,000 grant from the World Bank to launch an 18-month pilot program in Namibia. They linked 100 fuel cells and found that after being watered, the batteries could generate power for months through a connected circuit board. If the project is successful, Van Vuuren hopes the cells will offer a low-cost answer to rural Africa’s energy needs for years to come.