[wordup] Scientists have managed to coax bacteria into producing hydrogen

[Adam Shand]

Via: Mike Messick <mikem at tridigitalenterprises....>
From: http://www.newindpress.com/NewsItems.asp?ID=IE320050424061423

Scientists overcome 'fermentation barrier'
Sunday April 24 2005 16:35 IST

LOS ANGELES: Scientists have managed to coax bacteria into producing 
hydrogen - a development that would reduce the cost of waste water 
treatment.

Using a little amount of electricity - about 0.25 volts - scientists at 
Pennsylvania State University found that a microbial fuel cell can 
overcome its "fermentation barrier", Xinhua reports.

The voltage is just one-tenth needed for electrolysis - the process 
that uses electricity to break water down into hydrogen and oxygen.

"Basically, we use the same microbial fuel cell we developed to clean 
waste water and produce electricity. However, to produce hydrogen, we 
keep oxygen out of the microbial fuel cell and add a small amount of 
power into the system," said Bruce Logan, a professor who led the 
study.

In a paper "Electrochemically Assisted Microbial Production of Hydrogen 
from Acetate", the researchers explained that hydrogen production by 
bacterial fermentation was limited by "the fact that bacteria, without 
a power boost, can only convert carbohydrates to a limited amount of 
hydrogen - and a mixture of 'dead end' fermentation end-products such 
as acetic and butyric acids".

The voltage to be given, scientists explain, is a small fraction of the 
voltage needed to run a typical six-volt cell phone.

But it overcomes the "dead end" created during fermentation and 
produces four times more hydrogen than would be typically generated by 
fermentation alone.

Besides, the new process is not limited to using only 
carbohydrate-based biomass. Theoretically, it yields hydrogen from any 
biodegradable, dissolved, organic matter and cleans wastewater.

In the procedure, when the bacteria eat the biomass, they transfer 
electrons to an anode. The bacteria also release protons - hydrogen 
atoms stripped of their electrons - which go into solution.

Anode's electrons migrate via a wire to the cathode, the other 
electrode in the fuel cell, where they are electrochemically assisted 
to combine with protons to produce hydrogen gas.

The voltage is applied to the circuit by connecting the positive pole 
of a programmable power supply to the anode and the negative pole to 
the cathode.

The new process demonstrates, for the first time, the real potential in 
capturing hydrogen from renewable sources.