The City of Portland, Ore., has installed a 200-kilowatt fuel cell in its wastewater treatment plant that uses methane produced by the plant to generate power to run the plant, thus reducing the purchase of electricity from power stations.
For years Portland had been creative in finding uses for its methane. Some was used to heat boilers in the wastewater plant, and some was sold to a neighboring asphalt roofing company. However, the plant still produced more methane than the City could use.
Fuel cell power plants (FCPP) offered a viable solution. Fuel cells use an electric generation technology that converts methane into electricity, water, CO2 and usable heat. They also can be powered by other fuel sources such as hydrogen. With local policies to support sustainable practices and utilization of anaerobic digester gas (ADG), Portland has begun to power a fuel cell with methane from its wastewater treatment plant to generate electricity and heat to the facility.
In July 1998, Portland purchased and installed an ADG fuel cell for the Columbia Boulevard Waste Treatment Plant. With maintenance staff trained in operations, the fuel cell was operational by July 1999.
Many social, economic and environmental objectives are expected to be achieved through installation of the fuel cell. They include
? implementing a power source that is cost effective and responsible to taxpayers,
? reducing gaseous emissions by reducing hot flaring of surplus ADG,
? reducing net CO2 emissions, and
? supporting and promoting renewable generation in Portland.
Three key factors led to the decision to install the fuel cell at the plant.
? The FCPP had to be technically feasible. Testing of ADG showed it was capable of sustaining full operation of a 200 kW FCPP. Further study showed impurities could be "scrubbed" to meet FCPP gas operating parameters.
? The project had to meet environmental and renewable energy requirements. Unlike combustion generators that produce oxides of nitrogen (NOx), oxides of sulphur (SOx) and particulates, the FCPP process produces only water, heat and CO2 emissions. Also, by using a renewable biogas, the electricity is defined as renewable generation, or "green power," by U.S. definition.
? The project had to be economically viable. Although the initial installation cost is high, access to a combination of grants, tax credits and equipment lease financing cut the City?s cost in half.
The FCPP has the capacity to produce 1.5 million kWh of energy annually. It currently is producing approximately 1.3 million kWh of energy?about the same as that required to meet the demand from 110 Portland homes.
Portland?s long-range plan is to add additional hydrogen fuel cells or other technologies to produce clean power. The FCPP will be monitored for power output, reliability and maintenance. If successful, and as financial resources permit, up to ten fuel cells may be placed at the wastewater facility to generate two megawatts (2,000 kW) of green power?approximately 40 percent of the facility?s electricity needs.