A step by step diagram of the production process from crop waste to fuel.  (Source: Bruce Logan and Shaoan Cheng, Penn State)

Penn State's Microbial Electrolysis Cell (MEC) in action. The cell is shown with a power source used to jump-start hydrogen production in the bacteria. Bacteria grow in the anode chamber, forming a biofilm on graphite granules, while hydrogen gas is released at the cathode and bubbles up and into the tube on top of the reactor.  (Source: Bruce Logan and Shaoan Cheng, Penn State)
Hydrogen fuel may soon be nearly as plentiful and cheap due to record setting efficiency

Hydrogen is the optimal fuel in terms of the cleanliness of its burn reaction.  It burns cleanly; producing only water, unlike carbon based fossil fuels which also produce CO2 and other hydrocarbon derivatives.  However, hydrogen has suffered from two key problems; one problem is storage; the other problem is production.

Traditional production of hydrogen via electrolysis (applying an electrical current to water) is not very efficient as you are expending energy to apply the electricity.  It also requires the use of fossil fuels or some other alternative energy structure to produce this power for the production infrastructure.

However, research Bruce Logan and his colleagues at Penn State aim to toss traditional production out the window and revolutionize the way hydrogen is produced.  Their approach -- let special bacteria break down plant matter and byproducts producing hydrogen -- with almost no human produced the necessary power. The process is highly efficient and could be easily scalable to mass production.

The researchers had previously had good success with their waste water cell that used these bacteria process organic waste.   Now the researchers, funded by a National Science Foundation grant, have made modifications to their cell design which improve the living conditions for the bacteria, and they add a small jolt of electricity at the start of the process to excite them (note this is a trivial energy expense when compared to electrolysis). 

The end result is that their microbes are churning out hydrogen at record efficiency.  They call their new cell the Microbial Electrolysis Cell (MEC).

"We achieved the highest hydrogen yields ever obtained with this approach from different sources of organic matter, such as yields of 91percent using vinegar (acetic acid) and 68 percent using cellulose," said Logan.

Wait... the cell is using crops right, didn't DailyTech just run a piece pointing out the downsides of ethanol and biofuel production?  Well the key thing to notice here and why this technology is so promising is that it has 68 percent efficiency in releasing hydrogen from cellulose.  This means that the process can run on waste materials, including, but not limited to -- crop husks and stalks, lawn waste, field grass, and tree clippings and waste.  Traditional ethanol production requires either hydrocarbons from fossil fuels or the fermentation of sugary plants.  This necessitates sugary crops such as corn or sugarcane to be grown solely for fuel, not for human use.  Bacteria-produced ethanol and enzymatic produced ethanol are both being researched, but they have been very costly, and have relatively low efficiencies.

Logan and his team found that with certain configurations nearly all the hydrogen in the source material could be converted into hydrogen gas.  He foresees this allowing for the process to be adopted on a large scale for easy hydrogen production. 

Even with the initial electrical jolt, energy lost to processing the hydrogen and other inputs, the overall efficiency of the system is 80 percent in the vinegar driven system.  This is far better than any existing process for ethanol generation.  It also handily beats electrolysis generation, being between three to ten times more efficient

"We can do that by using the bacteria to efficiently extract energy from the organic matter," said Logan.

Logan and lead author Shaoan Cheng have published their findings in the November 12, 2007 online version of Proceedings of the National Academy of Sciences.

The National Science Foundation is ecstatic about Logan's work and the successes of Logan's team. 

"Bruce Logan is a clear leader in this area of research on sustainable energy," Bruce Hamilton, NSF director of the environmental sustainability program at NSF and the officer overseeing Logan's research grant said. "Advances in sustainable energy capabilities are of paramount importance to our nation's security and economic well-being. We have been supporting his cutting-edge research on microbial fuel cells for a number of years and it is wonderful to see the outstanding results that he continues to produce."

The promise of this technology is that it takes a time immemorial human waste -- crop waste -- and turns it into fuel that could one day power our vehicles.  Better yet it does it in a clean way, producing only water upon burn.

With advances in hydrogen storage technology, for example solid state storage, this will make producing and distributing fuel to power next generation hydrogen cars, such as Honda's FCX Clarity fuel cell vehicle, an easy process.   Perhaps the solution to mankind's energy woes and our salvation from dwindling fossil fuel supplies will come in the form of the oldest living organisms on earth -- bacteria.

Logan is also working with the National Science Foundation to use his waste water cells to produce fuel from human sewage, treating the sewage water in the process.  Bruce Logan, Hong Liu and Stephen Grot have been featured as Popular Mechanics Breakthrough Award recipients.

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