Hybrid Fuel Cells and the Bioenergy Future

UK researchers have combined two types of fuel cells, and made some important discoveries about the use of solid carbon--including biomass carbon--in efficient fuel cell power production.

Direct carbon fuel cells run on solid carbon fuel and typically use solid oxide or molten carbonate electrolytes to transport ions between the electrodes. John Irvine at the University of St Andrews and colleagues made a hybrid direct carbon fuel cell containing both types of electrolyte. They found that the binary electrolyte system enhanced carbon oxidation because carbon was oxidised not only on the electrode surface but also in the carbon-electrolyte slurry...

Solid carbon, which comes from various sources such as coal or plants, packs a lot of energy into a small volume, making it an attractive fuel. Irvine states that coal will be a major energy source in the future but, unless it can be converted into electricity more efficiently, will lead to an increase in carbon dioxide emissions. Fuel cells could be the answer, he says. 'Carbon fuel cells offer very high efficiency of conversion and, if implemented in the correct way, can yield two to three times the amount of energy for a given amount of coal compared to conventional thermal generation,' he explains. __Source_via_fuelcellworks

The carbon fuel cell appears to be an even more efficient means to produce cellulosic electricity than using the gasification to turbine (steam or gas) routes. Thermal generation from coal or torrefied biomass may achieve 30% to 40% electric generation efficiency (above 50% in combined cycle operation). Fuel cell generation efficiencies might reach above 80% combined cycle, eventually higher.

The promise of 90% or higher efficiencies from biomass electricity production is a potent goal.