January 23, 2006
SIUC researcher using coal to generate hydrogen
CARBONDALE, Ill. -- Imagine pulling into your nearest Perrier station and filling your car's fuel tank with water.
It could be done, maintains an engineer at Southern Illinois University Carbondale, and maybe sooner than you think.
"Twenty years ago we had stationary phones, and you had to wait in line to talk on a pay phone," says Tomasz Wiltowski, an associate professor of mechanical engineering and energy processes.
"But technology caught up — now we have cell phones."
Technology will do the same with fuel — it has to, Wiltowski says.
"Producing fuels in an economically and environmentally acceptable manner is a huge problem and will be more of a problem in the near future," he says.
"The car is part of our daily life. We have to do something in order to have fuel."
In Wiltowski's lab, that something involves the production of hydrogen that could be used to drive a car, among other things. The source of this hydrogen? Good, old-fashioned coal — a resource America has plenty of.
"There are different numbers on our oil reserves — I think it's something like 40 or so years until we run out — but we have plenty of coal, something like 400 years' worth, and it can be used to produce cleaner energy," Wiltowski says.
Coal, especially the high-sulfur coal found in Illinois, has a bad rep as a dirty fuel. That's true when it's burned, Wiltowski admits, but who says you have to burn it? Wiltowski is focusing on gasification, a process that turns solid coal into a gas made mostly of hydrogen and carbon monoxide. The resulting "syngas," when burned, produces nearly twice as much usable energy as coal.
"There are not many centers in the U.S. working to produce hydrogen from coal — we are one of the few," Wiltowski said.
While syngas burns more cleanly than coal, it does produce carbon dioxide, a major "greenhouse" gas associated with global warming. So Wiltowski is taking gasification one step further, breaking the syngas down into its two components, then oxidizing the carbon monoxide to make carbon dioxide. The beauty of this approach, he says, is that it produces extremely pure forms of both hydrogen and carbon dioxide.
"High-purity hydrogen is required to operate fuel cells," he says. "Lower-purity hydrogen can be used, but those impurities may produce unwanted emissions."
The carbon dioxide could be stored underground (a process called geological sequestration), but because of its purity, that might not be the best approach. Soda manufacturers, for example, could use that pure power for fizz.
"This is my approach: Produce a pure product — not a waste product — and sell it," he says.
To do that, Wiltowski has come up with a combination gasifier/reactor that can turn coal into gas and then turn that gas into hydrogen and carbon dioxide in 15-minute cycles. He adds water to the gasifier at the beginning of the process. When it turns to steam, not only does it speed up the process, but the steam (basically vaporized water) lends its hydrogen to the syngas.
"It produces about 60 percent more hydrogen than would normally be available in the syngas stream," Wiltowski says.
It takes two steps — two different chemical reactions — to process the syngas into hydrogen and carbon dioxide. Wiltowski has altered the chemistry of one of the materials involved in each reaction so they can be used over and over again, which helps cut costs.
"Typically, you can use (the original, unaltered forms) only a few times, but we have tested (the altered forms) in up to 50 (two-step) cycles, and their activity remains the same with no loss of hydrogen," Wiltowski said.
"Based on our results, we believe we could reuse them as many as 300 times before they would have to be replaced."
One of the reactions in the process generates heat; the other requires it. To further cut costs, Wiltowski uses the generated heat from the one to power the other.
In yet another cost-saving feature, the reactor where all this takes place has two chambers, each capable of running both reactions. Switching back and forth between the two allows the reactor to run continuously with no down time.
Wiltowski said his results to date have shown such promise that he's ready to move to the big time.
"There's enough data to scale up the process to full commercial size," he noted.
Wiltowski is also thinking ahead to the next step: turning some of that pure hydrogen into fuel for cars, truck, buses and the like. Many researchers are working on some variation of fuel cells, which combine hydrogen and oxygen to produce enough electricity to run an engine.
"I don't believe the design of the gasoline engine would have to be transformed to run on hydrogen — perhaps all you would have to do is change the timing," Wiltowski mused.
"The problem is, how can you store the hydrogen in the car — what kind of a fuel tank would you need? We are starting to work on that now in my lab."
Wiltowski's idea involves a hydrogen "cartridge" manufactured by the same plant that would turn coal into hydrogen. Drivers would pick up cartridges from the gas station, load them into their cars, fill up with water to create the reaction needed to power the engine and, when they had used up the cartridges, bring them back to the gas station for regeneration.
"I have three graduate students and three (post-doctoral researchers) working on my research projects, including the cartridge idea," he said.
"We have an automotive department on campus, so our plan is to work with them and get an engine to see how well it would operate on hydrogen. It's important to work on this — we don't have many other solutions, and we don't have much in our oil reserves. Once they are empty, that's it."
Leading in research, scholarly and creative activities is among the goals of Southern at 150: Building Excellence Through Commitment, the blueprint the University is following as it approaches its 150th anniversary in 2019.