Crab shells boost fuel cells

Remnants of crab and lobster shells could help prolong the life of microbial fuel cells that power sensors in the unlit depths of the sea, according to a team of Penn State University researchers.

Microbial fuel cells process organic material to produce energy, but deep sea sediments can be low in organic material because living things at a depth where light penetrates the water are used up before they reach the ocean floor. An absence of organics limits the lifetime of marine microbial fuel cells.

The researchers include chitin from processed crustacean shells into a cushioned anode made of carbon cloth. The anode is placed in the sediment or hung in the water where naturally occurring bacteria can eat the chitin.

‘This approach is good for deeper ocean areas or anywhere we want to increase the power of marine microbial fuel cells,’ said Bruce E. Logan, Professor of Environmental Engineering.

Microbial fuel cells work through the action of bacteria which can pass electrons to an anode. The electrons flow from the anode through a wire to the cathode, producing an electric current. In the process, the bacteria consume organic matter in the water or sediment. The Penn State approach uses the bacteria that naturally occur in the oceans and because so many sea creatures produce chitinous shells, many marine bacteria break down chitin.