Novel fuel cell design boosts carbon to energy efficiency

The new direct carbon fuel cell (DCFC) design allows it to exploit three times as much energy in the fuel as previous cells.

Materials like biomass and coal can be used in the cell, which will improve the potential for carbon capture as the new process only emits CO₂, rather than the mix of pollutants that come out of current coal-fired plants, researchers said. The fuel cell looks like a green, ceramic watch battery, about as thick as a piece of paper. They can be stacked on top of each other depending on the application.

The new design also allows the cell to run at far lower temperatures: with older cells running at 700 to 900 degrees Celsius, these cells can operate between 500 and 600 hundred degrees. The researchers hope that the increased efficiency might allow the new cell to exceed hydrogen fuel cells in terms of efficiency. "You can skip the energy-intensive step of producing hydrogen," said co-author Dong Ding.

The lower operating temperatures will also allow the cell to be made of less expensive materials, as they won’t have to stand as much heat.

The team achieved greater efficiency by using finely ground solid carbon injected into the cell via airstream and developing an electrolyte made of highly conductive doped cerium oxide and carbonate (which perform best under lower temperatures). These techniques are then combined with a 3D ceramic textile anode that uses bundled fibres to maximise surface area available for combustion. Finally, they developed a composite fuel made of solid carbon and carbonate, which at the operating temperature of the cell melts and flows into the solid fibres of the anode to increase the power density of the fuel cell.

The research comes out of the US Department of Energy’s Idaho National Laboratory and is set to be published in the 25 January issue of Advanced Materials. Dong Ding said that North American Energy companies had already shown interest in the technology.

Biomass has come under criticism recently over claims about its position as a renewable biofuel, with MIT releasing a study last week specifically calling out the EU’s proposition to extensively use biomass as a part of its upcoming Renewable Energy Directive (RED II).