The week of 4 June saw start-up of the world’s first SOFC/gas-turbine hybrid system, at the US National Fuel Cell Research Center in Irvine, CA, with Southern California Edison the sponsoring utility. The system includes a pressurised module integrated with a microturbine/generator providing a combined output of 220 kWe. The system is the proof of concept for the hybrid design and is the prototype for commercial hybrid systems.

In the hybrid technology, which is envisaged for use in electricity-only plants, pressurised SOFC (Solid Oxide Fuel Cell) modules act as topping units for one or more gas turbines, resulting in a very efficient combined cycle plant. Electrical efficiencies are expected to be as high as 60 per cent to over 70 per cent, with NOx emissions in the region of 0.5 ppm. Once in full commercial production the hybrid units are expected to cost around $1300-1500/kW, which will entail a substantial fall in price compared with current levels.

For cogeneration applications, unpressurised SOFC units with no gas turbine bottoming cycle would be used.

Siemens Westinghouse believes commercial production of power plants using its SOFC technology could begin as early as 2002, with first deliveries in 2004. Market entry products will be in the power range 0.3-5 MW and will be targetted at the “distributed generation segment of the all-electric and the generation/cogeneration markets.” These units will be unattended and are expected to have a very high availability.

Current projects

As well as the Irvine installation, Siemens Westinghouse is also involved in a number of other SOFC projects, including:

100 kW demonstration plant at Westervoort in the Netherlands for EDB/ELSAM, which has been operating since 1998.

A 250 kW commercial prototype SOFC cogeneration system being supplied to Ontario Power Technologies, with co-operation from the Canadian government and the US Department of Energy.

A 250 kW plant to be installed in Norway and operated by Norske Shell to demonstrate that the carbon dioxide normally emitted in exhaust gases can be recovered at low additional cost.

Several key pre-commercial installations to be implemented in partnership with utilities, including a 320 kWe and a 1 MWe pressurised hybrid (see illustration, bottom right). “We are optimistic that the utility consortiums that we are currently working with to facilitate demonstration programs for our SOFC Systems in Europe will be a near term reality and that work will begin this summer with utilities in Germany, France and Italy,” said Alan Casanova of Siemens Westinghouse at the recent Power Gen show in Helsinki.