The science of producing hydrogen to power fuel-cells in microbial electrolysis processes has just received a boost with some research at Pennsylvania State University that uses stainless steel components instead of the more expensive platinum.
Typically in a microbial electrolysis cell biological material is broken down by hordes of microbes that cluster around a metallic anode–the cell is in vacuum, and the electrons produced by the organic process hop over to the cell’s cathode where they grab a proton. The result is gaseous hydrogen forming at the anode of the cell: this is the fuel that electricity-generating hydrogen fuel cells need.
The electrode designs used until now required the use of platinum as a catalyst. And as well as being a rare resource with a potentially short-term useful life, platinum is terribly expensive: currently over $1,000 per ounce. This of course pushes up the price of microbial hydrogen generation processes, and potentially renders them useless on a large scale like that needed for commercial production.
But the team led by Professor Bruce Logan at Penn State U. have been researching alternatives to platinum. One candidate for its material resilience and low price is stainless steel–but when used in normal microbe cells its efficiency is only a third of a platinum cathode. Logan’s team found that by making the stainless steel into a dense-bristled brush they produced a cathode that matched or even surpasses that of a platinum one. Their small experimental setup previously used a $0.15 platinum cathode, whereas the new steel one costs a mere $0.03.
The next stage of the research is likely to be optimizing the chemistry of the stainless steel as well as the physical design of the brush-shaped electrodes. When the microbial cells are scaled up from laboratory sizes towards industrial production sizes, hydrogen gas becoming trapped in the bristles, and ion transport across long distances in the cell, become an issue.
The technology’s promises are vast: In theory waste food and water and the right microbes are all that’s needed to produce hydrogen, which can then be “burned” in fuel cells to generate electricity. And that whole eco-friendly production loop has potentially a much smaller carbon footprint than many current energy production methods. Now that platinum isn’t needed in the design, it looks like microbe fuel-generation might become a useful tech in the near future.
[via Technology Review]