The announcement that the world’s first fuel cell-gas turbine hybrid system had passed a key site acceptance test made interesting reading. US Energy Secretary Spencer Abraham commented: “This new technology has the potential to alter the landscape of tomorrow’s power industry.” Well it will – a bit. And not just yet.

The joint announcement at the end of March by Abraham, Siemens Westinghouse Corp. and Southern California Edison outlined that a 200 kW system had passed the 1000 hour proof-of-concept period. The system installed at the National Fuel Cell Research Centre on the Campus of the University of California-Irvine, is owned by Southern California Edison. It uses a solid oxide fuel cell in ‘combined cycle’ mode with an Ingersoll Rand microturbine, whereby the hot pressurized exhaust from the fuel cell is used to drive the microturbine.

In addition to such systems ‘changing the landscape of the power industry’, Abraham also said that they could “make distributed generation a reality” and added “… it could play a key role in strengthening the security and reliability of our power supply.” And this is where the future role of such systems lies.

Predominantly due to costs, distributed generation (DG) is unlikely to ever replace larger centralized power but there is a market for DG products. Allan Casanova, director of business development of Siemens Westinghouse’s stationary fuel cell division, said: “In 2005, when considering all fuel cells, the market is in the region of 1 GW – the US represents 50-60 per cent of this. We see these systems as complementary to central station power – for grid support, power quality and on site power applications… but we need to have a value proposition which allows the customer to generate electricity in the

5-10 cents/kWh range from systems of 5-20 MW.”

Siemens Westinghouse realises that the efficiency and outputs of hybrid systems must move to higher ratings. With the volatility and recent highs of gas prices around the world, improved efficiency is especially important to making the system economics work for the end user.

Currently, two more slightly larger proof-of-concept systems are being built in Europe – for RWE in Germany, and Edison SpA in Milan, Italy. These are 300 kW systems which have some changes in subsystems compared to the California installation. They are expected to achieve higher efficiencies than the 53 per cent of the Californian system. The RWE system will start up in late summer, while the system in Italy will be in operation “later this year”. The plan is to run the systems for one year, with system tests occurring in late 2003/04.

Casanova noted: “We also plan a 550 kW pressurized hybrid system and we are looking at these 300 kW and 500 kW systems as base product, proof-of-concept systems. The key challenge to having a high efficiency hybrid is a definite purpose microturbine or small gas turbine that gives us a better match with the air flows from the fuel cell and the outlet and inlet temperatures of the turbine we are interfacing with. When we go to multi-megawatt systems we can get a much better match from gas turbines that are more readily available.”

Pressurized hybrid systems will not be commercially available until around 2005. Scale up to multi-megawatt systems will then take place over the next couple of years after this. “We need to have these bigger systems with efficiencies of 58-70 per cent since this is the size at which we could give the distribution utilities the opportunity to provide grid support at the substation level,” said Casanova.

Commercial fuel cells, and systems incorporating their use, have been a long time coming and there is still a lot of work to be done. Siemens Westinghouse is focussing on the commercial launch of a 250 kW, atmospheric CHP system before scaling up to the pressurized hybrid. Randy Zwirn, president and CEO of Siemens Westinghouse Corp. noted: “Now, after 20 years of researching and developing fuel cell technology and implementing projects like the Irvine system, we plan to deploy our first fuel cell products in the commercial market by the fall of 2003.”

Certainly, I have been writing about fuel cells and hybrid fuel cell systems with 70 per cent efficiencies for at least ten years and will probably be writing about them periodically for some time to come. “So how long before we get there?” The best we can offer is: “Soon darling.”