The UK’s AMEC has expanded its sustainable energy project portfolio by winning a contract to provide engineering services for a next-generation geothermal power plant in California, USA.

Under a $6.8 million contract awarded by EnergySource LLC, AMEC will be responsible for design, engineering, training and assistance during the construction and start-up phase of the Hudson Ranch I project. The plant is the first stand-alone flash geothermal plant to be built at California’s Salton Sea geothermal site in recent years.

“This project is one of a new generation of high-temperature flash technology geothermal plants and another great addition to AMEC’s portfolio of sustainable energy projects,” said Tim Gelbar, President of AMEC’s Power & Process Americas business. “We have been involved with this project for several years and it fully aligns with our Vision 2015 strategy, which further defines our key market sectors and strengthens the focus on renewable and clean energy.”

Construction of the 49 MW, $350 million project has already started and should be completed by 2012. The plant will produce electricity from naturally occurring geothermal steam stored in superheated water reservoirs thousands of feet beneath the earth’s surface.

The facility will be a triple-flash plant using high-temperature Crystalliser Reactor Clarifier (CRC) technology to process the geothermal brine and steam from the Salton Sea production wells. The plant will include a turbine-generator, cooling tower, wellhead separators, crystallizer, water tanks, primary and secondary clarifier tanks, control building, office buildings, substation, pipelines and supports, various ancillary structures and associated internal roadways.

EnergySource announced the start of construction of Hudson Ranch I in May 2010 and says that the project will benefit from Federal tax incentives contained in the American Recovery and Reinvestment Act. Electricity from the plant will be purchased by Salt River Project, a major southwestern US utility.