An interesting article from Distributed Energy magazine discusses a methane gas-fed fuel cell power unit developed by diesel and gas engine maker Wartsila. According to the article, the Finnish company’s WFC20 is the first solid oxide fuel cell unit run on methane rich landfill gas.
Wartsila has finished the first phase of its validation program for the fuel cell unit, which has been in successful operation for more than 1500 hours.Â
Wartsila owns several international patent applications relating to power plant technology, including combined cycle operating methods that recycle waste heat and a method of operating a combined fuel cell – piston engine plant.
The WFC20 is based on planar solid oxide fuel cell (SOFC) technology supplied by Danish fuel cell maker Topsoe Fuel Cell A/S (Topsoe). According to Topsoe’s web site, SOFC fuel cells are the most efficient fuel cells available, recuperating the heat from its high operational temperature.Â
Topsoe owns several international patent applications directed to its SOFC technology and fuel cell stacks, including Application No. PCT/EP2008/000527 (‘527 Application).
The ‘527 Application is directed to an SOFC stack and clamping structure that uses a flexible sheet instead of conventional planar end plate flanges. This reduces the amount of material needed for the fuel cell stack. Â
The SOFC stack is inserted between two insulating blocks (12) (second insulating block on opposite side not shown).  The flexible sheet 15 is forced into a convex shape when in contact with the insulating end block 12.
According to the ‘527 Application, the flexible sheet 15 does not have to withstand bending forces so the mechanical tension lies in the plane of the flexible sheet, thus avoiding deformation of the fuel cell components.  The compressive force is obtained after clamping using nuts 8, springs 7 and tie rods 6.Â
