Volunteers head to the venue of the Fourth China (Taiyuan) International Energy Industry Expo held in Taiyuan, capital of coal-rich Shanxi province, Sept 16, 2012. The three-day event that kicked off Sunday is themed "Green energy and transformation", featuring industry breakthroughs in the fields of coal and coalbed gas, water, electricity, natural gas and new energies. Shanxi province was designated as a pilot zone for energy transformation in 2010. [Photo/Xinhua] 

Visitors are drawn to a town gas booth at the Fourth China (Taiyuan) International Energy Industry Expo in Taiyuan, Shanxi province, Sept 16, 2012. [Photo/Xinhua]