Many experts would agree that, as such, (solid) biofuels are most efficient when burned or gasified in power plants for electricity generation, and not in their liquid form as transport fuels. The electricity from this biomass could then possibly be used to power electric vehicles. Hydrogen for its part is often associated with highly efficient fuel cells (even though the gas can be burned in ICE's). On the other hand, the clean gas is merely an energy carrier and so a primary energy source must be used to convert water or hydrogen-rich gases into H2. If fossil fuels are used for the generation of the gas, then hydrogen loses its 'clean' credentials.
Now suppose you could join the best aspects of both the biofuels and the hydrogen economy: use a liquid biofuel like ethanol in combination with a highly efficient fuel cell that powers an efficient motor. This would make for a very intersting concept, but would require a dedicated fuel cell that can handle biofuels. Luckily, a handful of researchers are working on this kind of 'direct-alcohol fuel cells' (DAFC).
Earlier we referred to Acta Nanotech, an Italian catalyst developer, which developed such a fuel cell and demonstrated its reliability when used by a range of fuels, from hydrogen and methanol, to more complex hydrocarbons including ethanol and ethylene glycol (previous post). The Acta fuel cell relies on the company's Hypermec catalysts which are highly active because of their very small particle size and exceptional controlled dispersion. They are active below freezing (with ethylene glycol fuel) and are stable to over 800°C.
Most importantly, the catalyst is platinum free, which offers the potential for low cost mass production, but does generate comparable power to conventional platinum/ruthenium catalysts. The catalysts are selective and so they are not affected by fuel crossover and can work with novel stack designs. They are also unaffected by carbon monoxide poisoning.
Acta Nanotech supplied fuel cell components to power the world's first fuel cell demonstrator vehicle that was fuelled directly by bio-ethanol. The components were delivered to a team from the German Hochschule Offenburg (University of Applied Sciences) which demonstrated the direct ethanol fuel cell vehicle at the Shell Eco-Marathon race, held in France on 13 May 2007.
The vehicle was originally designed to work on a hydrogen fuel cell and came in second out of eight in the fuel cell category under this configuration, achieving a mileage of 2716 kilometres(6,491 miles per gallon). After the event, the team used the same vehicle to test the DAFC with ethanol (see picture, click to enlarge). Since the Eco-Marathon does not have a category for this new concept yet, the vehicle demonstrated the technology as a side-event to the official race:
bioenergy :: biofuels :: energy :: sustainability :: ethanol :: fuel cell :: DAFC :: efficiency :: Eco-Marathon ::
The team from Offenburg chose to use Hypermec catalysts and electrodes to allow their demonstrator vehicle to run directly on ethanol fuel. In so doing, they also built the first 50W ethanol fuel cell stack to use Hypermec and anion exchange membranes.
At the 2007 European Shell Eco-marathon, 65 vehicles used alternative energy sources during the event – an increase of 36% over 2006. These included 31 teams using biofuels, 26 using hydrogen cells and 7 teams that relied solar power. The most significant increase was in the use of hydrogen fuel cells, up by 50% over last year.
Last year, an ethanol vehicle made by students from the French Lycee La Joliverie won the competition and beat the fuel cell cars running on hydrogen, as well as ICE-powered cars running on other fuels.
Image: the team from the Hochschule Offenburg after the test-drive with the DAFC. Courtesy: Boris Kubrak.
EDIT: this article was edited on May 20, 2007.
Shell Eco-Marathon competition: The 2007 European Shell Eco-marathon – efficiency at its best [*.pdf] - May 13, 2007.
Acta Nanotech: Practical fuel options for new fuel cell applications.
On last year's ethanol victory: Environment News Service: Ethanol Car Beats Fuel Cells to Win European Eco-marathon - May 22, 2006.
Fuel Cell Today: Bioethanol fuel cell vehicle in Eco-marathon - May 15, 2007.
Hochschule Offenberg: FH-News Januar/Februar 2007 - Schluckspecht soll Ethanol schlucken [*German], February 2007.