Fuel from bacteria and salt water?

A bucket of water and a handful of bacteria could be all that is needed to produce an inexhaustible supply of pure hydrogen to power the green engines of tomorrow

    Agrain of salt or two may be all that microbial electrolysis cells need to produce hydrogen from wastewater or organic byproducts, without adding carbon dioxide to the atmosphere or using grid electricity, according to Penn State engineers.
    “This system could produce hydrogen anyplace that there is wastewater near sea water,” said Bruce Logan, professor of Environmental Engineering. “It uses no grid electricity and is completely carbon neutral. It is an inexhaustible source of energy.”
    Microbial electrolysis cells that produce hydrogen are the basis of this recent work, but previously, to produce hydrogen, the fuel cells required some electrical input. Now, Logan, working with Younggy Kim is using the difference between river water and seawater to add the extra energy needed to produce hydrogen.
    Their results, published in the Proceedings of the National Academy of Sciences, “show that pure hydrogen gas can efficiently be produced from virtually limitless supplies of seawater and river water and biodegradable organic matter.” 

    Logan’s cells were between 58 and 64 per cent efficient and produced between 0.8 to 1.6 cubic metres of hydrogen for every cubic meter of liquid through the cell each day. The researchers estimated that only about 1 per cent of the energy produced in the cell was needed to pump water through the system.
    The key to these microbial electrolysis cells is reverse-electrodialysis or RED that extracts energy from the ionic differences between salt water and fresh water.
    For RED technology to hydrolyse water – split it into hydrogen and oxygen – requires 1.8 volts, which would in practice require about 25 pairs of membrane sand increase pumping resistance.
    “Biodegradable liquids and cellulose waste are abundant and with no energy in and hydrogen out we can get rid of wastewater and by-products. This could be an inexhaustible source of energy.”
    Logan and Kim’s research used platinum as a catalyst on the cathode, but subsequent experimentation showed that a non-precious metal catalyst, molybdenum sulfide, had 51 per cent energy efficiency.