Wärtsilä Corporation, a leading global provider of power 
plants for decentralized power generation, was selected to deliver a 
163 MWe gas-fired power plant to Pacific Gas and Electric Company 
(PG&E), one of the largest gas and electric utilities in the United 
States. 
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 their 
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 Mr. 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 fuelled by natural 
gas, and will be capable of using fuel oil as back-up 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. 
Wärtsilä’s dual fuel engine technology - a competitive and popular 
alternative to gas turbines
The Wärtsilä 50DF lean-burn dual-fuel engine is the most powerful gas-
burning engine on the market today and its design incorporates 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 
back-up fuel oil. The engines are fully capable of automatically 
changing from gas to back-up 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 
gas mode.
About Wärtsilä Corporation:
Wärtsilä enhances the business of its customers by providing them 
with complete lifecycle power solutions. When creating better and 
environmentally compatible technologies, Wärtsilä focuses on the 
marine and energy markets with products and solutions as well as 
services. Through innovative products and services, Wärtsilä sets out 
to be the most valued business partner of all its customers. This is 
achieved by the dedication of more than 12,000 professionals manning 
130 Wärtsilä offices in over 60 countries around the world.
www.wartsila.com
About Pacific Gas and Electric Company:
Pacific Gas and Electric Company incorporated in California in 1905, 
is one of the largest combination natural gas and electric utilities 
in the United States. Based in San Francisco, the company is a 
subsidiary of PG&E Corporation (NYSE: PCG – News). Pacific Gas and 
Electric Company’s primary business is the transmission and delivery 
of energy. The company provides natural gas and electric service to 
approximately 15 million people throughout a 70,000- square-mile 
service area in northern and central California. The service area 
stretches from Eureka in the north to Bakersfield in the south, and 
from the Pacific Ocean in the west to the Sierra Nevada in the east. 
http://www.pge.com
For further information, please contact:
Maria Nystrand
Public Relations Manager, Power Plants
Wärtsilä 
Direct tel: +358 10 709 1456
Direct fax: +358 10 709 1425
e-mail: maria.nystrand@wartsila.com
Internet: www.wartsila.com