China and the United States are strengthening ties in reducing carbon emissions through new agreements involving energy efficiency cooperation, despite recent trade disputes over renewable energy products.

The world's two largest energy users signed four agreements during the third China-US Energy Efficiency forum on Wednesday.

In one case, the China National Energy Conservation Center agreed with the San Francisco government to work on energy efficiency policy research, high-technology product commercialization and demonstration projects.

More than 30 Chinese renewable energy companies have set up offices or headquarters in the city, which plans to get all of its energy from renewable sources within 10 years.

Currently, San Francisco gets more than 40 percent of its electricity from renewable sources, according to Deputy Mayor Jennifer Matz.

The Ministry of Transport and Medwestvaco, a US packaging company, will jointly establish a technology innovation laboratory.

Honeywell International Inc and the Pacific Northwest National Laboratory also signed agreements with China Environment Science Press and the Ministry of Housing and Urban-Rural Development to cooperate in energy-efficient buildings and rural energy conservation.

"China and the US are complementary in many ways, including technology research and development", said Xie Zhenhua, vice-chairman of the National Development and Reform Commission.

However, trade disputes have intensified after the US government decided to impose duties on China-made solar panels and wind towers.

The US government also said that Chinese manufacturers of towers for wind turbines had received unfair subsidies and must pay duties of 13 to 26 percent.

This move came after the US Department of Commerce imposed tariffs of 3 to 5 percent in March, and in May ordered additional tariffs of 31 percent to nearly 250 percent on Chinese solar panels. Experts said US solar market growth will slow because of these duties.

However, the US has also been a beneficiary of Chinese investment in US energy technology. The most recent such move came when Chinese firm Wanxiang USA Holdings Corp invested $420 million in GreatPoint Energy, a Massachusetts coal-to-gas plant.

Chinese investment in US "clean technology" is estimated to have exceeded $6 billion since 2006.

Meanwhile, more opportunities are likely as China plans to spend $27 billion this year to promote energy conservation, emission reductions and renewable energy.

The Ministry of Finance said it wants to promote energy-saving products, solar and wind power, and accelerate the development of renewable energy and hybrid cars.

China aims to cut its greenhouse gas emissions by 40 to 45 percent by 2020, compared with 2003 levels.

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