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Spanish fuel cell exceeds the target of power marked by USA
02 July 2012
A group of researchers from UNED has developed a method for manufacturing a component of the fuel cells that allows to exceed the target of power marked by the Department of Energy of the United States (US DOE) for 2017.
The technique, which has been patented, copes with any fuel cell size from laboratory to marketable dimensions and could be used for low cost industrial production.
"In the area of fuel cells, the US Department of Energy has set targets to be achieved during 2017-2020. Some of these targets have been already surpassed in our lab", says Pedro Luis Garcia Ybarra, professor at the Department of Mathematical Physics and Fluids of the UNED.
With ultra-low platinum loadings of 0.01 mg/cm2 in both electrodes, the platinum utilization was so high that PEM fuel cells delivered powers reaching up to 10 kW per gram of platinum. This figure improves the U.S. DOE forecast for the period 2017-20 (8 kW per gram of platinum with a loading ten times higher).
Typically, fuel cells generate electricity using hydrogen and air. This process is clean and the flue gases consist exclusively of water vapour instead of releasing CO2, such as the usual car engines working with gasoline or diesel. In addition, if hydrogen were produced from renewable energies (for instance, by water hydrolysis from wind or solar energy) total pollution of the energy cycle could be reduced to a minimum.
To overcome the performance marked by the U.S. authorities, scientists have optimized an element of the PEM fuel cell called MEA (Membrane-Electrode Assembly). "This component is common to all polymeric fuel cells", says Jose Luis Castillo, a professor of the same department.
Controlling material properties
The result has been patented by the investigators as a method for depositing thin nanostructured layers of electrocatalyst particles on the fuel cell electrodes, which are joined by simple contact on both sides of the polymeric membrane, making the MEA.
The methodology used for the deposition of the catalytic layer (electrospraying) is the key to increase the performance. "We were able to control the morphological properties (porosity and roughness) of the material generated by the catalyst particles when deposited, substantially increasing the active surface", says Castillo, and adds: "as the performance depends on the surface of the catalyst particles exposed to the reactive gas, and it was made very large, we have reached a high performance".
Another advantage is the simplicity of the procedure to be scaled-up: the same components of the deposition technique used in the laboratory can be applied on an industrial scale with a very low cost, avoiding the difficulties encountered with other methods.
An element in the renewable cycle
The cost of the platinum catalyst is about the 30% of the total price of a fuel cell. Hence to build fuel cells at competitive prices is one of the challenges pursued by the research community. Inexpensive fuel cells are aimed to be used by the automotive industry, replacing internal combustion engines by electric motors powered by fuel cells.
Lowering costs and increasing performance could also allow to exploit another of its possible applications: to solve the problem of discontinuity in the renewable electricity generation by matching production to demand. Currently, electric accumulators (batteries) solve the problem, but fuel cells would be a more simple and economical way.
"One idea is to use the excess of electricity generated at valley hours of demand to produce hydrogen and store it. So, when a peak of demand occurs, fuel cells could be connected to the grid to achieve an additional generation of electricity", explains Garcia Ybarra. "So, you can get a steady production of energy from renewable sources", he adds.
Scientists try not only to reduce the price of fuel cell components but also to enlarge its durability. So far, a fuel cell with the MEA developed by these researchers has been operating for more than 1,000 hours without interruption.