48 nanotimes News in Brief

Fuel Cells // New SOFC System Reaches Record Efficiency © Based on Material by Frances White, PNNL

Pacific Northwest National Laboratory (US) developed a highly efficient, small-scale solid oxide fuel cell system that features PNNL-developed microchannel technology and two unusual processes, called external steam reforming and fuel recycling.The smaller system uses methane, the primary component of natural gas, as its fuel. The entire system was streamlined to make it more efficient and scalable by using PNNL-developed microchannel technology in combination with processes called external steam reforming and fuel recycling. The key to the efficiency of this small SOFC system is the use of a PNNL-developed microchannel technology in the system‘s multiple heat exchangers. Instead of having just one wall that separates the two gases, PNNL‘s microchannel heat exchangers have multiple walls created by a series of tiny looping channels that are narrower than a paper clip. 

The second unique aspect of the system is that it recycles. Specifically, the system uses the exhaust, made up of steam and heat byproducts, coming from the anode to maintain the steam reforming process. This recycling means the system doesn‘t need an electric device that heats water to create steam. Reusing the steam, which is mixed with fuel, also means the system is able to use up some of the leftover fuel it wasn't able to consume when the fuel first moved through the fuel cell.

Image: PNNL‘s new, small-scale solid oxide fuel cell system can achieve up to 57% efficiency partly because it uses a heat exchanger with PNNL-developed microchannel technology. Microchannels narrower than a paper clip are etched onto the heat exchanger‘s shim, which has been removed in this photo for illustrative purposes. Lab tests showed the system‘s net efficiency ranged from 48.2% at 2.2 kW to a high of 56.6% at 1.7 kW. © PNNL

Mike Powell, Kerry Meinhardt, Vince Sprenkle, Larry Chick, Gary McVay: Demonstration of a highly efficient solid oxide fuel cell power system using adiabatic steam reforming and anode gas recirculation, In: Journal of Power Sources, Volume 205, May 01, 2012, Pages 377-384, DOI:10.1016/j.jpowsour.2012.01.098:

http://dx.doi.org/10.1016/j.jpowsour.2012.01.098