Engineering news
Researchers at the Georgia Institute of Technology in the US created a prototype cell, which uses a newly invented catalyst from collaborators at the University of Kansas to convert the greenhouse gas into more precious hydrogen.
The cell has “high potential to some day electrically power homes and perhaps cars” in a decentralised energy network, said the team. The fuel is cheap and readily available, and the cell has a much lower operating temperature than previous examples – a “striking engineering accomplishment,” the researchers claimed.
“Lowering the temperature to 500ºC is a sensation… very few people have even tried it," said Ben deGlee, one of the first authors of the study. Methane fuel cells usually run at 750-1,000ºC, but the new technology is even cooler than 600ºC car engines. "When you get that low, it makes the job of the engineer designing the stack and connected technologies much easier,” he added.
Improvements throughout the small cell helped achieve the cooling, said the researchers. The cells would be combined into shoebox-sized ‘stacks’, with stainless steel capable of acting as interconnector thanks to the lower temperatures.
The research was based on a type of fuel cell with reportedly high potential for commercial viability, the solid-oxide fuel cell (SOFC). Solid-oxide cells are known for their versatility in fuels they can use.
With hybrid and electric cars currently leading the way in the alternatively fuelled vehicle sector, the new cell might not power cars “for a while”. It could, however, be installed in basements for a cleaner, cheaper power grid.
“The hope is you could install this device like a tank-less water heater. It would run off of natural gas to power your house," said study leader Meilin Liu. "That would save society and industry the enormous cost of new power plants and large electrical grid expansions."
He added: "It would make homes and businesses more power independent… that kind of system would be called distributed generation, and our sponsors want to develop that.”
Hydrogen is the best fuel for powering fuel cells, said the researchers, but it is very expensive. The researchers worked out how to convert methane to hydrogen in the fuel cell itself using the new catalyst, which is made with cerium, nickel and ruthenium.
When methane and water molecules come into contact with the catalyst and heat, nickel chemically ‘cleaves’ the methane molecule while ruthenium does the same with water. The resulting parts come back together as desirable hydrogen (H2) and less desirable carbon monoxide (CO).
H2 and CO continue on to further catalyst layers that make up the anode, making the gases into positively charged ions. Expelled electrons travel through a wire towards the cathode.
There, oxygen “sucks up” the electrons, closing the electrical circuit and becoming O2 ions. Ionised hydrogen and oxygen meet and exit the system as water condensation, while the carbon monoxide and oxygen ions meet to become pure carbon dioxide, which could be captured.
Fuel-cell technology creates “far, far less carbon dioxide” than combustion engines, the researchers added.
The work was published in Nature Energy.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.