Fuel cell efficiency

Researchers have developed a converter that can boost low DC voltage produced by solid oxide fuel cell stacks to the higher voltage required for conversion to AC for commercial applications.

Researchers at Virginia Polytechnic Institute and State University have developed a converter that can boost low DC voltage produced by solid oxide fuel cell stacks to the higher voltage required for conversion to AC for domestic and commercial applications.

Virginia Tech, which is applying for a patent on the technology, developed its converter in the US Department of Energy’s Solid State Energy Conversion Alliance (SECA) Program, created to hasten the development of solid oxide fuel cells so they could be affordably marketed for power generation.

“The significance of Virginia Tech’s work is that it facilitates the downsizing of the fuel cell stack and boosts net power output, while at the same time reducing the size and cost of the electronic systems behind it, key technical objectives for maturing solid oxide fuel cell technology to commercial-market self-sustainable status,” said National Energy Technology Laboratory (NETL) Project Manager Don Collins.

Virginia Tech’s device, when combined with highly efficient switching and digital control techniques, converts 22 volts to 400 volts at 97 percent energy efficiency. The device is able to boost voltage and reduce 120-hertz ripple current to two percent without the costly, bulky capacitors or additional converters that are customarily used.

The net effect is that fuel consumption, the size of fuel cell systems, and costs are reduced, thereby taking a significant step toward SECA’s goal of 40-60 percent overall fuel cell efficiency at a cost of $400 per kilowatt by 2010. SECA studies indicate that each one percent improvement in inverter efficiency can reduce fuel cell stack costs by $5 to $10 per kilowatt.

Once costs are reduced to the $400 per kilowatt level and efficiency goals are attained, fuel cells can be used as power generation resources in a variety of ways, such as onsite power for houses and commercial properties, transportation, and modular application by utilities.