BEIJING - China started commercial use of aviation biofuel on Wednesday, in a bid to ease fuel pressure and cut carbon emissions.

China's top oil refiner, Sinopec, was given a license allowing commercial use of its aviation biofuel, said the Civil Aviation Administration of China (CAAC).

The license, the first of its kind, permits Sinopec's No 1 Aviation Biofuel to be used by airlines, some of which have showed willingness to cooperate with the refiner.

Xu Chaoqun, deputy head of CAAC's Flight Criteria Department, said the development is a significant breakthrough for research, production and use of aviation biofuel.

The development also makes China the fourth country in the world to produce aviation biofuel, after the United States, France and Finland.

Sinopec started research on aviation biofuel in 2009, and its application for commercial use was accepted by CAAC in early 2012.

Last April, a test flight in Shanghai powered by the biofuel was a success, and the fuel went through several rounds of more strict tests before it was given the green light.

Sinopec can produce 3,000 tons of such oil a year, from materials like rape seed, cotton seed and wasted cooking oil.

The refiner is also considering joining with private enterprise in planting, collecting and processing materials, after working with McDonald's to collect cooking oil.

"Aviation biofuel is one of the major trends in global aviation," said Xu. "With our research on aviation biofuel, we have built a set of technological standards, and will have a bigger say in international carbon emission reduction." Research showed that carbon dioxide generated by biofuel is 45 percent or less than that produced by conventional fuel.

The International Air Transport Association forecast that 30 percent of aviation fuel will be biofuel by 2020, and a few western airlines have been testing commercial flights with biofuel since 2008.

China is the world's largest oil importer and 58.1 percent of its 2013 supply relied on imports.

With an annual consumption of nearly 20 million tons, China has become the second largest aviation fuel consumer and demand is estimated to be expanding by 10 percent every year, while the global average is less than 5 percent.

By contrast, the country has abundant biofuel-refining resources: vast areas of oil-rich plants and a huge amount of wasted cooking oil.

However, analysts said there may be a long way to go until large-scale application of aviation biofuel due to costs.

Xu Hui, vice director of Sinopec's Science and Technology Department, said the production costs of aviation biofuel are two to three times those of crude oil.

He said some three tons of wasted cooking oil can generate one ton of biofuel, and collecting cooking waste suitable for refining is expensive.

Refiners and airlines have to split the cost, and the final price will be determined by the market based on emission-cutting efforts and an application scale, according to Xu with Sinopec.

"The most important thing for now is to diversify biofuel sources and upgrade technology," said CAAC's Xu.