I've been a bit sceptical of hydrogen as a fuel of the future, mostly because with traditional hydrogen technology, you have to keep making the stuff from water and that usually needs a fair amount of electricity. So by the time you get through the whole process of making and transmitting the electricity, then making, storing, releasing and eventually using hydrogen, it would probably have been as efficient too burn coal to generate steam to power your vehicle as to use hydrogen.
Now, some researchers at Penn State University have harnessed bacteria to the challenge, at a stroke turning it into a biofuel (yay!) and, they claim, increasing the energy efficiency of the process which is described in Proceedings of the National Academy of Sciences. At the heart of the process lies a bio-electrochemically assisted microbial reactor
In other words to pep-up the hydrogen-generating-potential of the cells, which contained weak acetic acid (which typically is what you get when ethanol oxidises) they applied a small voltage (0.5-0.6V) and generated around 1.1m^3 hydrogen from each 1m^3 cell/day at an efficiency of around 82%.
There are several things I like about this. Firstly it relies on fermenting products found in waste water which, apart from the cost of the yeast, is free. Secondly, with a bit of luck the bacteria will be self sustaining (won't crawl out of its tank and go for world domination)
What I'm sceptical about... the rate of the reaction and the yield. It will take a relatively long time for the process of fermentation of organic matter to alcohol and its natural oxidation to acetic acid and finally how we are going to store and distribute the hydrogen generated?
Hattip to Wired.