A novel process for squeezing hydrogen out of biomass could mean a cheaper and easier way to make hydrogen for fuel cells.
A small company in Madison, WI has developed a novel way to generate hydrogen cheaply and cleanly from biomass.
In the next couple of weeks, the technology, developed by Virent Energy Systems, will be used for the first time to continuously produce electricity from a small 10-kilowatt generator at the company's facility in Madison. The unit is fueled by corn syrup, similar to the kind used by soft drinks manufacturers, says CEO Eric Apfelbach.
The company is also about to begin work on a $1 million U.S. Navy project to build portable fuel-cell generators. The goal is to make self-contained units capable of producing their own hydrogen from a biomass-derived glycerol solution or even antifreeze.
The vast majority of hydrogen is currently made from fossil fuels -- oil, coal, and, most commonly, natural gas, through a process called steam reforming. In this process, a mixture of steam and methane is heated to temperatures above 800 degrees Celsius, and then reacts with a catalyst to produce hydrogen and carbon monoxide.
Although it's possible to use a similar process to generate hydrogen from biomass-derived ethanol, there are disadvantages in doing so, says Robbie Burch, head of chemistry and chemical engineering at Queen's University Belfast in Northern Ireland. The high temperatures required and use of pressurized steam mean the conversion process only practical on the industrial scale, he says.
Virent's conversion process, which is called aqueous phase reforming (APR), avoids these problems by carrying out the reformation at relatively low temperatures and with liquids rather steam.
Their process is a significant advance, says Dave King at Pacific Northwest National Laboratory in Richland, WA, because it means you don't have to put as much energy into the system to make steam, and at the same time you're working with liquids, which have a higher energy density than gases for a given volume.
Furthermore, the process uses extremely active catalysts, which allow 15 times more hydrogen to be converted per gram of catalyst, compared with steam reforming, says CEO Apfelbach. This efficiency allows 90 percent of the feedstock to be converted in the first cycle, he says, and the rest to be recycled. As a result, Virent claims it's able to produce hydrogen for $2-3 per kilogram -- competitive with natural-gas-derived hydrogen.
The Navy's interest is in powering the increasing number of rechargeable batteries used in military equipment, ranging from night-vision goggles to communication and positioning equipment, says Apfelbach.
They want a unit no bigger than two cubic feet and quieter than a generator, he says. The result will be a device capable of producing about one kilowatt of electricity, enough to power about 20 laptops. Running the generator on antifreeze will be an added bonus, notes Apfelback, since the substance is already in the military supply chain.
By Duncan Graham-Rowe
Source : Technology Review
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