Integrated assessment of the environmental and economic effects of "coal-to-gas conversion" project in rural areas of northern China.

Northern China suffers from serious air pollution especially in winter, much of which derives from solid fuel used for domestic heating in rural areas. In order to reduce pollution emissions in the heating season, the Chinese government has introduced a "coal-to-gas conversion" policy, promoting a switch to natural gas which is much cleaner than the coal normally used for winter heating. The "coal-to-gas conversion" project will cover more than 1.8 billion m of heated built floor area and affect more than 12 million heat users in Beijing, Tianjin, Hebei, and the surrounding areas. Life cycle assessment and life cycle cost methods are applied to compare and analyze the environmental impact and economic cost of household energy usage for the whole year under 5 scenarios before and after "coal-to-gas conversion." In the three scenarios after "coal-to-gas conversion," the environmental impact decreases by around 50% while the total economic cost increases by around 80%. Particulate emissions responsible for air pollution are considerably reduced with accompanying benefits for human health, though significant, but reduced, impacts on freshwater and marine ecotoxicity remain. Improving thermal efficiency through natural gas utilization, implementing an energy-saving retrofit of rural housing, and promoting straw utilization yield benefits for people and the environment in rural areas of northern China.