Guest Post: Improved Fuel Cell for Electric Cars
Dec 08, 2011
By Olan Dantes
Extending the travel range of an electric car, like the Chevrolet Volt, requires the use of gas-powered generators. But running an electric car on a generator makes it just like a normal one less efficient and a fuel hog. That is without mentioning the added weight of a battery pack.
The answer to this problem could be what the researchers at the University of Maryland have developed. Their specialized fuel cell is the most efficient alternative yet to a gasoline generator. Similar to conventional fuel cells, it generates electricity through chemical reaction instead of burning fuel. This method can be twice as efficient as fuel combustion.
Their fuel cell is made from solid-oxide, an improved version of a solid ceramic electrolyte type cell. Solid-oxide fuel cells can run on a variety of readily available fuels like diesel and gasoline which is unlike the common hydrogen fuel cell. Although hydrogen fuel cells have been used for power generation on buildings, they are judged as impractical because of their size and their very high operating temperature which can reach up to 900?C.
The change in electrolyte material and the overall cell design allowed the researchers to create a much more compact fuel cell. Not just that, their fuel cell could also produce 10 times more power at a size similar to gasoline engines.
The researchers also managed to lower the operating temperature at a few hundred degrees. This improvement allows them to use materials that are at lower cost than those used in hydrogen fuel cells. Eric Wachsman, director of the University of Maryland Energy Research Center and research leader confirms the huge difference in cost. He says that his team has identified ways to further improve power output and reduce the temperature, using methods that are already showing a lot of promise. This could bring costs further down and can make its price as competitive as the price of gasoline engines. Wachsman adds that he is in the early stages of establishing a company for the commercialism of their fuel cell.
Wachsmans fuel cells currently operate at a temperature of 650 degrees C but he hopes he and his team could bring it down to 350 degrees C making it usable for cars. Insulation of the fuel cell is possible because of its small size a fuel cell stack to power a car would only be 10 centimeters high. The challenge is in dealing with high temperature since you will need expensive, heat-resistant materials within the device plus the fact that it takes time to heat up a fuel cell to operating temperatures. Wachsman and his team believe that if they manage to bring down the operating temperature, they can bring the cost further down by using less expensive materials and the time needed to start the cell will be reduced.
But even with these improvements, it is still impossible to turn on a fuel cell instantly. It would also be subject to wear and tear if it is subjected to constant switching for every short trip. The researchers counter this by providing a battery pack whose purpose is the same as combustion engines. With it, the fuel cell could run more steadily and the battery is at top condition if without any burst of acceleration.
The results achieved by the researchers were due to their efforts on modifying the solid electrolyte material at the core of a solid-oxide fuel cell. Fuel cells available on the market such as those made by Bloom Energy have thick electrolyte structures for better support. This thickness though limits power generation and so researchers have been finding other ways to support the cell besides the thick electrolyte. Wachsman and his team are the first to develop a multilayered electrolyte structure which is not only thinner but can also bring out more power even at lower temperatures.
The research conducted by the University of Maryland is actually a part of the continuous efforts of the U.S. Department of Energy to make practical solid-oxide fuel cells. The first fruits of that effort likely won't be fuel cells in carsso far, Wachsman has only made relatively small fuel cells, and significant engineering work remains to be done. The first applications of solid oxide fuels in vehicles may be on long-haul trucks with sleeper cabs.
Car equipment manufacturers like Delphi and Cummins are working on fuel cells that can power air conditioners, televisions and microwave ovens inside cabs which can cut fuel consumption by up to 85 percent as compared to resting the trucks engine. Delphis system also follows a thin electrolyte design but operates at a higher temperature than Wachsmans fuel cell. Delphis fuel cell could last a whole week running at low rates while maintaining the 85 percent reduction.
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