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Thursday, September 04, 2008

Microbes for Off-the-Grid Electricity

A new company is bringing microbial fuel cells to Africa.

By Kristina Grifantini

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Growing electricity: Stephen Lwendo, Lebônê cofounder and a junior at Harvard, explains to villagers how energy flows to the LED light.
Credit: Lebônê
Multimedia
photo  Click here to see the Lebônê team create fuel cells in a Tanzanian village.

Microbial fuel cells, which use electrodes in dirt to power a small motor, have long been more or less a laboratory curiosity. Because they generate such a small amount of power, developing them to charge devices would not be practical in places where electricity is readily available. However, Lebônê Solutions, a startup based in Cambridge, MA, aims to use microbial fuel cells to provide power to Africans who are off the grid. In some parts of Africa, a small amount of energy is enough for a few hours of lamp light in the evening, or for powering the ubiquitous cell phones--something that some residents will walk five hours to a generator to do, says Aviva Presser, a cofounder of Lebônê. The company is made up largely of Harvard University alumni and current Harvard students originally from African countries.

With funding from the Harvard Institute for Global Health, the team has recently completed a pilot study in Tanzania, where members brought six basic microbial fuel cells and taught residents how to use them. The team organized village meetings where team member and Tanzanian native Stephen Lwendo explained how to make the fuel cells.

The team found residents receptive to the idea of easy-to-grow power and keen to use the fuel cells to charge cell phones, run radios, and provide more light. "In Africa, people want to power [small] DC devices," as opposed to large AC devices like a refrigerator, says Lebônê cofounder Hugo Van Vuuren, a Harvard graduate and a South African native. The team hopes to develop the technology to make it competitive with other renewable energies in countries across Africa. Microbial fuel cells could have a distinct advantage because they are initially cheaper to build than a windmill and easier to set up than solar panels. What's more, they could last up to 10 years, says Lebônê cofounder David Sengeh.

Instead of using hydrogen as a fuel, as do conventional fuel cells, microbial fuel cells use naturally occurring microbes to generate power. Bacteria live in the anode, where they eat glucose, sewage, or other waste water, and turn that into electrons and protons. The bacteria transfer electrons to the circuit, which provides small amounts of power.

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Comments

  • How is this better?
    Thoms on 09/05/2008 at 7:47 AM
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    How is this better than hand cranked generator devices? My hand cranked flashlight was less then $10, lasts for hours and powers 1 to 3 LEDs. Similar devices are available for cellphones, TVs, radios, etc. This is proven, cheap, scalable technology. So how is the microbe technology better then hand cranked generators?
    Rate this comment: 12345
    • Re: How is this better?
      DJTal on 09/05/2008 at 8:30 AM
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      Well , i guess it's better because the microbes are doing the work , which saves human power . But , compared with having to walk 5 miles to a  generator , hand cranking would use less energy . Trust a bunch of highly intelligent Harvard students to come up with the most difficult way to generate power ........ poor Africans!! But , its a good thing now that we've been educated about microbial fuel cells .
      Rate this comment: 12345
      • Re: How is this better?
        mkogrady on 09/08/2008 at 8:29 PM
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        On a broader scale, these MFC's can use the waste water from a sewage system, or sediment from brackish ponds and lakes. In essence recycling waste for energy. The bacteria used in water treatment plants is an active culture that can be easily and readily sourced. The muck...well...it's easily sourced too I imagine.
        Rate this comment: 12345
  • How is it better?!
    myrightfoot on 09/05/2008 at 11:35 AM
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    It's better in a lot of way. First, these generators can be built out of common items. The only non local resources that you might need are the carbon filaments and power control.  If these items can be sourced at a low enough cost then thousands, if not millions of households could have their own bio generators. They can charge lots of items, have few mechanical parts that break down overtime, and everyone has waste that they can fuel the generators with. I think its brilliant in its simplicity and could be a great tool for million worldwide.
    Rate this comment: 12345
  • How Scalable is this?
    mkogrady on 09/08/2008 at 11:34 AM
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    If a bucket of muck and sand, one square meter of Graphite some chicken wire and sodium solution as a carrier is all it takes to power up a cell phone, how big of a system is needed to power up a house?

    Can a fuel cell the size of a VW bus be created to run a home, assuming you can route it through an inverter? Or - can the DC power be used to split water into hydrogen and power a gas generator directly?

    Once the muck is spent, is it tossed out and all the inner workings rinsed out with fresh water and a new system built with fresh muck? Does it pose any envirmental challenge?

    What muck works best or what would you look for as a base?
    Rate this comment: 12345
    • Re: How Scalable is this?
      kgrifant on 09/08/2008 at 2:33 PM
      Technology Review TR Staff
      Editorial Assistant
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      3
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      Because this fuel cell yields about 1 watt per meter squared of anode, it would take quite a bit of surface area to power a house. Instead, the team hopes to provide small amounts of power to farmers. Waste from the fuel cell can be used as fertilizer--there are no hazardous byproducts. Soil, manure from domestic animals, and other organic-rich waste works best.
      Rate this comment: 12345
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