Construction has officially began on a US$3.7 billion dam in southwest China, AP reported. The Xiangjiaba dam is a 6-gigawatt project on the upper reaches of the Yangtze that will displace between 88,000 to 150,000 people, according to state media. Construction formally began Sunday and is expected to be completed by 2015. China plans to build a dozen hydropower stations along the river's upper stages despite criticism about the environmental and social impact of such projects. Hydroelectric power, however, is relatively clean compared to coal-fired plants, which are currently the main source of energy in China. Xiangjiaba and the nearby 12.6 gigawatt Xiluodu dam will combine to produce more power than the Three Gorges dam.