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May 09, 2011

Project for Microbial fuel cells that will cost about one dollar and use dirt - Truly dirt cheap cellphone chargers

Aviva Presser Aiden (Harvard) and colleagues are working to develop microbial-based cell phone charger to increase access to health care via mobile apps. Their project to use dirt-powered batteries to charge cell phones in Africa won a $100,000 grant from The Bill and Melinda Gates Foundation today.

The goal is to make a charger would cost of order a dollar and could completely charge a phone in 24 hours. Furthermore, unlike solar panels, MFCs do not require any sophisticated materials: they can be easily assembled in only a few minutes. As cultural knowledge of MFC technology spreads, Africans will become capable of assembling their own chargers almost entirely from scratch, and at minimal cost that will be recouped with the very first recharge."

Aiden has already demonstrated the effectiveness of the MFC-approach, building MFCs that can produce enough to power LED lights for use in homes in regions such as Tanzania and Namibia. Moreover, the MFCs were able to operate continuously in the lab for 14 months.

The Geobacter project is a related effort to use geobacter bacteria for power

Geobacter species also have the ability to transfer electrons on to the surface of electrodes. As outlined under the Microbial Fuel Cell link, this has made it possible to design novel microbial fuel cells which can efficiently convert waste organic matter and renewable biomass to electricity.



Cell phones are becoming a ubiquitous and increasingly crucial part of the health care infrastructure of the developing world. The devices provide a critical gateway to health information and offer contact with physicians who cannot reach remote locations.

For instance, even in Sub-Saharan Africa, where 500 million people lack power in their homes, 22 percent of households have cell phones. Keeping the devices charged, however, can be a challenge.

"For households lacking power in Sub-Saharan Africa, recharging a cell phone battery often means a long, possibly multi-hour walk to a charging station, where recharges cost between 50 cents and a dollar," says Aiden. "Because the per-capita income is several hundred dollars per year, this is a significant cost. Existing solutions for charging cell phones in off-grid areas are inadequate. For instance, a solar-panel based charger costs around $20, and is difficult to even bring to market because of poor access and inability to repair them if they break."

The solution is the use of an natural abundant source of energy: microbial power. Certain naturally occurring soil microbes produce free electrons during the course of their ordinary metabolic processes. A Microbial Fuel Cell (MFC) uses a conductive surface to harvest these electrons and use them as a power source.

Following the completion of the pilot program, Aiden hopes to follow-up with a larger-scale project, distributing chargers across broader region, thereby demonstrating the viability of this approach to charging cellular phones in developing world contexts.

Environmental Microbiology -Power output and columbic efficiencies from biofilms of Geobacter sulfurreducens comparable to mixed community microbial fuel cells

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