The unit is some­what larger than a washing machine, but much fancier with its dark gray and black surfaces and shining blue LED display. But as is so often the case, outward appear­ances are not what matters. In contin­uous oper­a­tion, the BlueGEN BG-15 fuel cell unit gener­ates about 13,000 kilo­watt-hours of low-emis­sion elec­tricity per year. And since waste heat results from the conver­sion of natural gas to elec­tricity, the power plant also gener­ates up to 250 liters of hot water per day.

Cool improve­ment

Clean elec­tricity is a key issue for the future, and interest in green energy is growing. So decen­tral­ized power gener­a­tion using combined heat and power systems is gaining in impor­tance. For Frank Dahlmanns, product manager at Solid­power GmbH in Heins­berg, Germany, solid oxide fuel cell tech­nology is one of the most promising candi­dates among future models for elec­tricity gener­a­tion. He says, “With the natural gas-powered BlueGEN family, it has been possible to achieve a consid­er­able shift in the effi­ciency ratio for the first time. Thanks to their high elec­trical effi­ciency of over 55 percent, the units can — in contrast to motor-driven micro CHP systems — operate contin­u­ously and produce enough elec­tricity for private homes and medium-sized commer­cial build­ings.” Solid oxide fuel cells (SOFCs) convert natural gas into hydrogen-rich process gas from which elec­tricity is produced through an elec­tro­chem­ical reac­tion — the fuel cell reac­tion. The rugged design of the fuel cell stack in the BlueGEN BG-15 makes it possible to modu­late the output.

BlueGEN makes very low-emis­sion elec­tricity from natural gas for house­holds, elec­tric cars and the power grid. Its waste heat gener­ates hot water. And main­te­nance can be done easily via online moni­toring.

“Users can send their personal load profiles via a cell phone app and a Web app to the system to control it,” says Dahlmanns. “Depending on require­ments, they can operate the BlueGEN BG-15 at outputs from 500 to 1,500 watts.” So its output can be reduced during vaca­tions and increased again to recharge the battery in an elec­tric car. The reduc­tion of the exhaust gas temper­a­ture to less than 120 degrees is an impor­tant improve­ment in the unit. Reducing the exhaust gas temper­a­ture enables the use of conven­tional plastic exhaust systems like those typi­cally used in gas burners. That makes installing the BlueGEN BG-15 ­easier. Dahlmanns says, “That’s an impor­tant aspect for marketing the unit, because heating installers are impor­tant multi­pliers for us. They’re the ones who ulti­mately recom­mend our product to end customers.”

With its high elec­trical effi­ciency the BlueGEN BG-15 can generate enough elec­tricity for resi­den­tial and medium-sized office build­ings. (Photo: SOLID­power)

Clever mixing

Fans from ebm-papst play an impor­tant role in both reducing the exhaust gas temper­a­ture and supplying the process gas. Dahlmanns says, “We’ve been using NRG118 EC centrifugal blowers since we began to develop the BlueGEN tech­nology. They’re powerful and rugged, char­ac­ter­is­tics that are indis­pens­able for contin­uous oper­a­tion.” One of the centrifugal fans makes sure that the exhaust gas temper­a­ture remains below 120 degrees. The other supplies the air for the elec­tro­chem­ical conver­sion process in the fuel cell stack and cools it at the same time. The supplied control valve with stepper motor regu­lates the amounts of reac­tion and cooling air with a 3/2-way valve.

Gas for the future

With its improve­ments in BlueGEN tech­nology for a modu­lated power gener­ator for contin­uous oper­a­tion, Solid­power over­came several chal­lenges for future-proof power supply models. Now it is time to estab­lish the condi­tions for making the BlueGEN BG-15 more attrac­tively priced inde­pen­dently of state subsi­dies. Dahlmanns says, “We’re working on the service life of the units and of course on estab­lishing fuel cell tech­nology as green tech­nology.”