Distributed generation speeds demand for fuel cells

Jerry Leitman

Hans Maru

Christopher R. Bentley

FuelCell Energy Inc.

Field trials beginning this year will lead to commercial introduction in 2001 of a new kind of stationary power plant designed to provide clean, quiet, high quality, reliable, uninterrupted, efficiently generated power.

The plant uses the Direct FuelCell, produced by FuelCell Energy Inc. (FCE), headquartered in Danbury, Conn., with manufacturing in Torrington, Conn. Increased demand for distributed generation is one of the major trends driving interest in the fuel cells as alternatives or supplements to large central station power plants and their long transmission lines.

Operation and benefits

Fuel cells are the cleanest and most efficient fossil fuel electric generators available, with virtually zero pollutant emissions and twice the efficiency of turbine plants, making them ideal for distributed generation. The Direct FuelCell emits only water, carbon dioxide and minimal traces of nitrogen oxide and sulfur dioxide. Conventional turbine generators attain maximum efficiency at a single design point, and the efficiency drops off sharply at lower or higher loads. In contrast, fuel cells operate at constant efficiency. This allows power to be provided from small-scale facilities that fit well into landscapes and neighborhoods.

The fuel cell`s quiet and pollution-free operation is due to the fact that, also unlike a turbine plant, electricity is generated without combustion and rotating machinery. Instead, much like a battery, a fuel cell is an electrochemical engine. It converts chemical energy within a fuel to direct current (dc) electricity. So a fuel cell plant can be located next to a hospital, or in residential or urban areas, without concern about noise or spoiling the environment.

Fuel cells make electricity by combining hydrogen ions, drawn from a hydrogen-containing fuel, with oxygen. Most conventional fuel cells require an external reforming device to produce the hydrogen, which is then sent to the fuel cell. With the Direct FuelCell, the fuel is fed directly into the stack of fuel cells that is assembled to reach the desired power level; no external reforming is required. While natural gas is the primary fuel, with appropriate cleanup any hydrocarbon fuel-including gas from landfills, wastewater treatment anaerobic digesters, coal mines or liquid fuel-can be supplied to the fuel cell.

Advantages resulting from the internal reforming process include:

– elimination of the costly separate external fuel reforming unit;

– lower equipment count, which simplifies operation and increases reliability;

– increased system efficiency, ranging from 50 to 55 percent, compared to 35 to 40 percent for low temperature fuel cells; and

– even higher efficiencies, expected to be above 70 percent, from another FCE development, the Direct FuelCell/turbine hybrid power plant. In this design, fuel cell waste heat is used to produce electricity in a non-combustion gas turbine cycle.

Demonstration projects

The Direct FuelCell was first demonstrated at the megawatt scale under a “proof-of-concept” project in which a 2 MW Direct FuelCell power plant was successfully built and operated in Santa Clara, Calif., for 4,000 hours in 1996 and 1997.

In addition to meeting and exceeding its rated power and ramping criteria, the power plant operations successfully met criteria for rated output, peak operation, voltage harmonic power quality, low nitrogen oxide and sulfur oxide emissions, and operation within noise limits.

The project`s balance-of-plant (BOP) proved to be exceptionally reliable. The system rode through minor grid disturbances and responded to major grid problems exactly as intended. The overall BOP availability during the test program was 99 percent.

After analyzing results of the Santa Clara plant, FCE designed and installed a 250-kilowatt (kW) power plant at Danbury. This, the largest single-stack advanced Direct FuelCell plant, had generated 1.25 million kilowatt hours (kWh) in 7,600 hours of operation from February 1999 through mid-January 2000. The plant uses cells that are 50 percent larger in area, 40 percent lighter per unit area and 30 percent thinner than those used at Santa Clara, thus doubling the power output of a single fuel cell stack.

FCE`s partner, Daimler Chrysler`s MTU Friedrichshafen unit, commissioned a Direct FuelCell system similar to the Danbury plant in November 1999. The facility will provide the city of Bielefeld (Germany) municipal power utility with up to 250 kW of electricity and byproduct high quality heat, demonstrating its use in cogeneration for further increased efficiency.

In another major development, the Los Angeles Department of Water and Power announced in December 1999 that it is working with FCE toward installing a 250-kW plant in Los Angeles.

Steps toward commercialization

In the commercial stationary power plant such as those in field trials, four 250 kW stacks are packaged in a 1 MW module. Commercial power plants of both 250 kW- and megawatt-class designs should be available following the field trials. The 3 MW unit that would typically power a light industrial plant would fit on a tennis court.

To make Direct FuelCells commercially attractive to end users who can benefit most from their features, FCE is working to reduce power generation costs from a current level of 15 cents per kWh to approximately 5 cents per kWh. FCE has automated fuel cell stack production and improved cost-effectiveness of manufacturing commercial fuel cell components. Expecting to reach commercial cost goals when it makes sales in the hundreds of megawatts per year, FCE also expects to reduce BOP costs by 30 percent from current levels.

Trends spur interest in fuel cells

At least two other accelerating trends will help create demand for the benefits of Direct FuelCells by the time they are commercially available:

– Energy industry deregulation. Federal legislation passed in 1992 requires utilities that own power and transmission lines to open them to any company that wants to rent capacity to transport power from a supplier to a consumer, regardless of location. Electric power industry deregulation unbundles the three primary components of electric service-generation, transmission and distribution. Deregulation also unbundles reliability and quality from price and the other “givens” of being chained to one local utility. Energy users will be able to shop around for power sources that provide features they want most.

– Dramatic growth of energy needs into the first quarter of the next century. Present installed capacity for generation in the United States is 750 million kW. The U.S. Department of Energy reported a projected need for 363 million kW of increased and replacement capacity between now and 2020. Natural gas, the fuel best suited for fuel cells, is projected to supply 80 percent of this new capacity. Globally, demands for new capacity are projected to reach 1,275 million kW by 2015.

Fuel cells and distributed generation are concepts that have been cited for years as constructive approaches to power generation. The Direct FuelCell`s ability to meet the needs of distributed generation plants to be efficient and environmentally acceptable means that both concepts now have their best chance ever to fulfill their potential. n

Leitman is president and CEO of FuelCell Energy; Maru and Bentley are executive vice presidents. More information about the Direct FuelCell, is available at 203-825-6000 and at web site www.fuelcellenergy.com.

Previous articlePOWERGRID_INTERNATIONAL Volume 5 Issue 2
Next articleELP Volume 78 Issue 4

No posts to display