Wärtsilä Corp. (Helsinki, Finland) was selected to deliver a 163 MWe gas-fired power plant to Pacific Gas and Electric Co. (PG&E; San Francisco, California, U.S.). The plant will be located in Humboldt Bay near Eureka in Northern California and is expected to enter commercial operation by mid-2009.

PG&E selected Wärtsilä's technology in order to repower its existing Humboldt Bay plant. The new facility will be 35% more efficient with 90% fewer air emissions. The agreement is subject to the approval of the California Public Utility Commission and environmental permits issued by the California Energy Commission.

“This project marks a significant entry for Wärtsilä in California. Wärtsilä gas engine technology is an outstanding choice for the utility's energy-shaping requirements, as well as for the state of California's increasing environmental concerns. Our technology offers high simple-cycle efficiency on full and part load, as well as other ancillary service benefits that make the Wärtsilä solution a natural choice for this operation,” says Frank Donnelly, vice president, power plants, Wärtsilä North America.

For the Humboldt Bay power plant, Wärtsilä will deliver 10 Wärtsilä 18V50DF lean-burn dual-fuel engines on an engineering, procurement and construction (EPC) basis. The engines will be fueled by natural gas, and will be capable of using fuel oil as backup during times of natural gas curtailment. The 163-MW plant will produce reliable electricity for the local grid in California's North Coast. The plant will produce enough electricity to serve roughly 125,000 California homes.

The Wärtsilä 50DF lean-burn dual-fuel engine is a powerful gas-burning engine designed to incorporate both low emissions and high fuel efficiency, making it a competitive alternative to gas turbines. It has become a popular engine for power plant installations in countries all over the world. It is available with up to 18 cylinders giving up to 16.64 MWe in continuous base-load operation. The 50DF features a 7608kJ/kWh heat rate, which is equivalent to an overall thermal efficiency of 47.3% at the busbars.

In the event of loss of gas pressure, the engines switch over to the backup fuel oil. The engines are fully capable of automatically changing from gas to backup liquid fuel instantly if the gas supply is interrupted, while continuing to deliver full power. When the gas supply is restored, it is then possible to immediately switch back to the gas mode.