As China's economy continues to soar, its energy use and greenhouse gas emissions¹ will keep on soaring as well—or so goes the conventional wisdom. A new analysis by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) now is challenging that notion, one widely held in both the United States and China. Well before mid-century, according to a new study by Berkeley Lab's China Energy Group, that nation's energy use will level off, even as its population edges past 1.4 billion. "I think this is very good news,'' says Mark Levine, co-author of the report, "China's Energy and Carbon Emissions Outlook to 2050" and director of the group. "There's been a perception（知觉，感觉） that China's rising prosperity means runaway² growth in energy consumption. Our study shows this won't be the case."

Along with China's rise as a world economic power have come a rapid climb in energy use and a related boost in man-made carbon dioxide emissions. In fact, China overtook the United States in 2007 as the world's leading emitter of greenhouse gases.

Yet according to this new forecast, the steeply rising curve of energy demand in China will begin to moderate between 2030 and 2035 and flatten³ thereafter. There will come a time—within the next two decades—when the number of people in China acquiring cars, larger homes, and other accouterments of industrialized societies will peak. It's a phenomenon known as saturation⁴（饱和） . "Once nearly every household owns a refrigerator, a washing machine, air conditioners and other appliances, and once housing area per capita has stabilized⁵, per household electricity growth will slow,'' Levine explains.

Similarly, China will reach saturation in road and rail construction before the 2030-2035 time frame, resulting in very large decreases in iron and steel demand. Additionally, other energy-intensive industries will see demand for their products flatten.

The Berkeley Lab report also anticipates the widespread use of electric cars, a significant drop in reliance on coal for electricity generation, and a big expansion in the use of nuclear power—all helping⁶ to drive down China's CO2 emissions. Although China has temporarily suspended approvals of new nuclear power plant construction in the wake of the disaster at Japan's Fukushima Daiichi Nuclear Power Station, the long-range forecast remains⁷ unchanged.

Key to the new findings is a deeper look at patterns of energy demand in China: a "bottom-up" modeling system that develops projections⁸ of energy use in far greater detail than standard methods and which is much more time- and labor-intensive to undertake. Work on the project has been ongoing⁹ for the last four years. "Other studies don't have this kind of detail,'' says Levine. "There's no model outside of China that even comes close to having this kind of information, such as our data on housing stock and appliances."

Not only does the report examine demand for appliances such as refrigerators and fans, it also makes predictions about adoption¹⁰ of improvements in the energy efficiency of such equipment – just as Americans are now buying more efficient washing machines, cars with better gas-mileage, and less power-hungry light bulbs.

Berkeley Lab researchers Nan Zhou, David Fridley, Michael McNeil, Nina Zheng, and Jing Ke co-authored the report with Levine. Their study is a "scenario¹¹ analysis" that forecasts two possible energy futures¹² for China, one an "accelerated improvement scenario" that assumes success for a very aggressive effort to improve energy efficiency, the other a more conservative（保守的） "continued improvement scenario" that meets less ambitious targets. Yet both of these scenarios¹³, at a different pace, show similar moderation effects and a flattening¹⁴ of energy consumption well before 2050.