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BEIJING -- Xu Shisen put down the phone and smiled. That was Canada calling, explained the chief engineer at a coal-fired power plant set among knockoff antique and art shops in a Beijing suburb. A Canadian company is interested in Mr. Xu's advances in bringing down the cost of stripping out greenhouse-gas emissions from burning coal.

Engineers led by Mr. Xu are working to unlock one of climate change's thorniest problems: how to burn coal without releasing carbon into the atmosphere.

Mr. Xu is part of a broader effort by China to introduce green technology to the world's fastest-growing industrial economy -- a mission so ambitious it could eventually reshape the business, just as China has done for everything from construction cranes to computers.

China looms large over the global climate summit in Copenhagen, where Chinese officials are pressing the U.S. and other rich nations to accept new curbs on their emissions and to continue to subsidize poor nations' efforts to adopt clean-energy technology. China is the world's biggest source of carbon emissions. Less understood is the way China is now becoming a source of some of the solutions.