But with imports rocketing and the environmental toll of dirty coal climbing -- Premier Wen Jiabao said on Monday it met 75 percent of the country's energy needs -- officials are eyeing an even more ambitious programme.

"By 2020 renewable energy (could) account for 15 percent of energy production in China, including large-scale hydropower projects," Shi Lishan, director of renewable energy at the policy-setting National Development and Reform Commission, told an energy conference in Beijing.

The new target was being discussed by top officials, he told Reuters on the sidelines of the conference, although he declined to give a date when it might be confirmed.

The impact on river systems of projects like the giant Three Gorges Dam, the largest in the world, means some environmentalists object to them being counted with generators like wind-turbines or solar panels.

At present renewable sources provide around 7 percent of China's energy, Shi said.

Acid rain affects around one-third of a country that the World Bank says has 20 of the 30 most air-polluted cities in the world, providing strong incentives to seek more clean energy.

Global warming is also a growing concern for the world's number-two emitter of greenhouse gases. China faces a range of natural challenges from desertification to seasonal typhoons that could be exacerbated by hotter weather.

It has approved the Kyoto Protocol on climate change and, although it has no obligation to cut carbon dioxide emissions during the pact's first phase to 2012, analysts say it is keen to show it is a good global citizen.

INDUSTRIAL CHANGE

Home to increasing numbers of energy-intensive factories -- its aluminium industry alone accounted for around five percent of all power used last year -- China should also consider shifting its economic structure in the long run, some experts say.

"Encouraging the growth of the service sector in China would...tend to make the economy less energy-intensive," David Dollar, World Bank director for China, told the conference.

"It's also true that most consumption is services, so if China has policies that encourage people to consume more, that would also tend to shift the industrial structure," he added.

The government has said it plans to crack down on inefficient firms, phasing out old and inefficient machinery.

"(We should) publish a list of those industries and enterprises that are backwards and high-energy consuming and force those businesses out of use," said Zhu Guangyao, deputy director of the State Environmental Protection Administration.