Capacity at three power plants will be expanded under an agreement signed on Monday between Saudi Aramco and cogeneration supplier Tihama Power Generation Co, a joint venture between International Power and Saudi Oger. Aramco generates power both through third-party companies that operate and produce electricity and also through its own power assets. It plans to double its power generation capacity to 4 gigawatts by 2015 as it brings new projects on stream. Cogeneration — combined heat and power generation — lowers carbon dioxide emissions and raises energy efficiency. Aramco has cogeneration plants in Berri, Uthmaniyah, Qatif, Abqaiq, Riyadh, Yanbu, Jeddah, Shaybah, Juaymah, Shedgum, Ras Tanura. Under the new energy conversion agreement deal (ECAs) which will last until 2026, three of four Tihama’s sites will be expanded by 532 megawatts and deliver 868 tons per hour of steam at oil and gas facilities Ju’aymah, Shedgum and Uthmaniyah. Shedgum and Uthmaniyah are two of the five operating areas of Ghawar, the world’s largest onshore oilfield. “Construction at all three sites is expected to start in May 2012 with a phased commencement of commercial operations between late 2014 and mid 2015,” the statement said. South Korea’s Hyundai Heavy Industries will carry out engineering, procurement and construction work while General Electric will supply gas turbines, it said. Tihama currently produces 1,063 MW of power and 2,000 tons per hour of steam at four sites in the Eastern Province.