China is likely to make commitment for a quantified target to limit its greenhouse gas emissions after 2020, as the world's top carbon emitter is feeling ever-increasing pressures from international climate talks, said a senior expert with a government think tank.

But it also depends on where the climate negotiations are going and China's domestic development stage by then, said Xu Huaqing, a researcher from Energy Research Institute affiliated with National Development and Reform Commission, the government body that oversees climate change issues in China.

This is the first time that China has mentioned a timetable regarding its absolute amount of greenhouse gas emissions. Previously China has pledged to cut carbon emissions per unit of economic growth by 40 to 45 percent by 2020 from 2005 levels.

Xu said China will need to spend over 1 billion yuan on energy conservation and developing renewable energy between now and 2020 to honor its commitment on reducing carbon intensity.

China's carbon emissions is still set to grow at a rapid pace in the coming years, as the country's coal-based energy structure is not likely to change in the short run, and its industrialization and urbanization will need further space for carbon emissions, according to Xu.

"The most optimistic scenario studies I've seen put a peak of China's carbon emissions at around 2030," he said, "while the majority researches estimate the peak will come between 2035 and 2045."

"So it is more reasonable for China to set a post-2020 target to restrict its carbon emissions, rather than a reduction goal," he said.

But the Chinese government is already considering controlling its total energy consumption in the 12th Five-Year Plan period (2011-2015), according to Xu.

"The goal is to restrict the total energy consumption at around 4 to 4.2 billion tons of coal equivalent by 2015," said Xu.

The country consumed 3.2 billion tons of standard coal in 2010, about 46 percent of what was used in the world.

The National Energy Administration is calculating detailed energy consumption caps for different regions based on their own development levels, according to Xu.

Increase in non-fossil energy will be exempted from the cap as a policy incentive for switching to renewable energy.

And the bureau is also mulling over a plan to set regional electricity consumption caps, according to Xu.

"This is because the electricity consumption is relatively easy to monitor, report and verify, and it is also very closely linked with coal consumption," he explained, but ruled out special caps for coal consumption.