Bigger and cleaner

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Shell Technology's fuel cell plans have been proceeding quickly. The first 250 kW fuel cell is already under construction in Kollsnes outside Bergen and will be completed in two years. Now the oil company, along with Statkraft and Aker Kværner, has launched plans for a much bigger fuel cell of between 10 and 20 MW. A giant, also internationally. The goal is to be the first to commercialise such a plant.

This is a so-called solid oxide fuel cell (SOFC). Such a fuel cell has an operating temperature of about 1,000 degrees and can use natural gas as a fuel. Most other fuel cell technologies have lower operating temperatures and are based on hydrogen.

SOFC technology is not new. Although Siemens Westinghouse in the USA has been producing such fuel cells for many years, the commercial market has yet to take off. What is unique about Shell technology is, as Teknisk Ukeblad reported in December, that it is fitted with an afterburner. This special afterburner is constructed in a manner similar to the main cell, but is equipped with a special exhaust manifold that separates the CO 2 gas from the nitrogen. In a normal solid oxide fuel cell, CO 2 gas is emitted along with the nitrogen into the atmosphere. In addition, the afterburner increases the total efficiency by increasing the electricity yield. In a large-scale plant, the hot exhaust gases can drive a gas turbine, which will bring the electricity yield up to 70 percent. This is about 10 percent more than from a conventional gas-fired plant, and it has a natural CO 2 recovery system to boot.

Needs funding

The first thing that needs to be done now is a pilot study to assess the technical and economic basis for building the large-scale SOFC plant. This study is to be ready in time for inclusion in the coming Report to the Storting on the use of natural gas. The three partners will also apply for funding for this ambitious project.

"If we receive a favourable response to our application, the plant can be completed by 2008," says Helge Skjæveland, the head of the sustainable development department of Shell Technology Norway. "It ought to fit it well with Norwegian commitments with regard to the Kyoto agreement."

Each of the partners has its own goals for the project. Shell wants to develop a power-generating technology for use on oil platforms. Traditional gas turbines are not very efficient and emit large quantities of CO2, triggering high taxes. Electric power supply based on an SOFC emits far less CO2, and almost nothing of other contaminants. It also concentrates the CO 2 gas, which can then be used for reinjection and increased oil extraction.

"This can become a very interesting win-win situation, both for us and for Norway," says Skjæveland.

Industrial challenge

Statkraft sees the SOFC technology as a possible source of supply for land-based electric power in the future. Its natural CO 2 separation and high efficiency may eventually make it the ideal gas-fired power technology for Norway.

For Aker Kværner the technology represents an exciting industrial challenge. Even though 30 to 40 percent of such a plant will be subcontractor deliveries from Siemens Westinghouse in the US, the rest will be built in this country. This is at about the same level as if this involved a conventional gas-fired power plant based on turbine technology. If the project is a success, Aker Kværner will have a considerable lead through the expertise it will have amassed.

"Both Rolls Royce and General Electric have now begun to show interest in this market. This is a good indication that commercialisation is near," says Skjæveland.