Sponsored by:

Comment, blog & share photos

Log in | Become a member
The Honolulu Advertiser
Posted on: Sunday, February 26, 2006

UH develops charcoal-fired fuel cell

By Jan TenBruggencate
Advertiser Science Writer


spacer spacer

Michael Antal holds charcoal from macadamia nut shells that can be used to cook food, as a filter or with his newly developed fuel cell.

JEFF WIDENER | The Honolulu Advertiser

spacer spacer

University of Hawai'i researcher Michael Antal has developed a working fuel cell that uses charcoal as its fuel and operates at bread-baking temperatures.

The Antal system, which he calls an aqueous alkali biocarbon fuel cell, is unlike other fuel cell technology both in that it uses a renewable fuel and that it does not require particularly high temperatures.

Renewable energy is the watchword in the modern energy debate, an effort pushed in large part by high global oil prices and the perception that global political instability threatens the availability of fuel.

Gov. Linda Lingle is backing a package of bills in the Legislature that includes strong support for renewables, and President Bush has been on the stump in recent weeks on behalf of energy initiatives that include hydrogen fuel cell cars, solar power, wind research, and more.

Most research today focuses on cells fueled with hydrogen, which must be manufactured— in many cases from fossil fuels.

But "this is effectively a battery that uses charcoal to make electricity," Antal said.

The technology has attracted interest from around the world, said Dick Cox, director of the university's Office of Technology Transfer and Economic Development.

"I think it's a tremendous innovation," Cox said. His office will license the technology to independent companies, which would pay Antal and the university for the use of the system.

Antal's cell operates at about 400 degrees Fahrenheit. By contrast, a carbon cell developed by the Lawrence Livermore National Laboratory operates at 1,500 degrees.

"People have been building hydrogen fuel cells for over a century. Our purpose is to awaken people to the fact that there are new things out there. We need to think outside the box," Antal said.

The key to his cell's operation is the very chemically reactive property of charcoal, which has a large surface area and burns at relatively low temperatures, he said.

Antal said he imagines industrial applications would be most appropriate for the fuel cell, but figures it might be capable of running an automobile. Antal's former associate, University of Tokyo researcher Kazuhiro Mochidzuki, said the system appears most appropriate for mid-sized power generation stations.

"Power generation by carbon fuel cell should not be in so big scale. The dispersed power system that does not require big generators is suitable for the carbon fuel cell," Mochidzuki said via e-mail.

Right now, his lab at the University of Hawai'i is fine-tuning the design, and looking for companies that would finance the development of a commercial charcoal fuel cell. Mochidzuki said there are still technical issues to be resolved.

"Carbon fuel cell is one of the promising technologies to obtain power from charcoal at a high efficiency. It can be said that the carbon fuel cell is an important technology to promote the sustainable biomass energy system," he said. However, "there are a number of problems to be solved against its practical use of carbon fuel cell, even if it theoretically has a good potential."

The carbon cell functions something like a car battery. It has an anode and cathode positive- and negative-charged terminals in a liquid solution, and if you put an electrical load — like a light bulb — between them, electrical current flows from one to the other. But that's where the similarity ends.

In Antal's cell, the electrolyte is alkaline potassium hydroxide, not sulphuric acid. It is kept under pressure to prevent it from boiling away at 400 degrees. The negative terminal, or cathode, which acts as a catalyst, is made of nickel and silver or platinum.

The positive terminal, or anode, is a porous ceramic column filled with charcoal powder. A piston keeps it pressurized, and serves at the attachment point for the electrical connection.

In operation, hydroxide ions in the electrolyte attack the carbon, creating carbon dioxide and water. The process releases energy.

The cell is fed air to provide the process with new oxygen, and it vents carbon dioxide.

The charcoal does not burn in the sense of a campfire burning. The reaction occurs entirely within the liquid of the fuel cell.

While fossil-fuel cells also produce carbon dioxide, a greenhouse gas, charcoal represents a sustainable source of fuel, since the living plants that produce the charcoal get their carbon by removing carbon dioxide from the atmosphere.

Antal said that water-based or aqueous fuel cells have a considerable history. A hydrogen-based aqueous fuel cell was used in the first Apollo space mission.

While his charcoal fuel cell works as it is, Antal said it needs to be more efficient, and his team is now fine tuning it — working with different catalysts, different electrolyte strengths and other changes. They also need to figure out how to continuously feed charcoal fuel to the system.

"Handling of solid fuel, such as charcoal, is not easy. If we want to feed charcoal into the cell continuously, we have to solve the problem how it can be fed. This is one of the biggest problems of solid fuel," Mochidzuki said.

Antal, who holds the University of Hawai'i's Coral Industries Chair of Renewable Energy Resources, is a longtime advocate of charcoal. Another of his projects is a flash carbonization reactor, which converts biomass like macadamia nut shells, wood and grass into charcoal. That charcoal can be used to cook food, as a filter or, in tandem with the new fuel cell, as a source of electricity.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.

• • •