Ai Guangzeng, 60, says the biogas she has been fueling her home with since 2006 is "good stuff."

"It's much cleaner burning than coal or firewood," she says, pointing to the blue flame on the stove in her home in a remote village in Guizhou Province.

Ai sees only two other significant aspects to the methane gas: it has cut her coal consumption by half and spares her the arduous chore of chopping firewood.

However, Ai Xinglong, energy office chief of Guizhou's Kaiyang County, sees a direct link from the gas stove to the United Nations climate change conference, which opened Monday in Copenhagen.

He is anxious that the conference participants keep pushing forward the Cleaner Development Mechanism (CDM), an arrangement under the Kyoto Protocol that allows industrialised countries with greenhouse gas reduction commitments to invest in ventures that cut emissions in developing countries as an alternative to more expensive emission reductions in their own countries.

Ai Xinglong is responsible for the local methane program and has been busily encouraging local farmers to build biogas generating pools, also called the methane digesters, to reduce the consumption of coal and wood, so limiting carbon dioxide emissions.

He wants to know whether the Copenhagen conference will keep endorsing the CDM, so the biogas farmers in Kaiyang can be "rewarded" with money by selling the amount of emissions reduced by using methane.

"The money can be used as a follow-up fund for our methane program. It's very important," he says.

With the help of a consulting firm in Guizhou, Kaiyang's methane program has been listed as one of China's CDM programs, and has applied for registration in March as a UN CDM program.

"If all goes well, the program will be registered by the UN CDM Executive Board next October, so we can start the real deal," says He Junyuan, general manager of Guizhou Zhongshui Hengyuan Project Management and Consulting Co. Ltd.

Japan's biggest carbon trading company Eco Asset is willing to buy the reduced emissions by Kaiyang's 15,000 methane pools for 8.2 euros (12.3 U.S. dollars) per tonne, says He.

If the deal is clinched, the county could earn 430,000 euros (645,000 dollars) a year, with 60 percent distributed to methane farmers.

"The cost of a methane pool is 30 percent construction and 70 percent maintenance," says Ai Xinglong. "If it's not well-maintained, it will not produce biogas, then the preliminary investment will be a total waste.

"In relatively poor regions like Guizhou, many people can't afford the cost of methane pool maintenance."

Ai Guangzeng's four sons are all working away from home, so the elderly hire young people to clear the residue in their methane pool and stir the biogas slurry.

"We have to spend hundreds of yuan on the cleaning, which is very hard," she says.

China has been promoting biogas utilization in rural areas to make use of renewable energy and protect the environment.

Experts estimate that binding the CDM with China's rural methane program will help fund construction and maintenance of methane digesters, ensuring normal operation of big methane projects, and promoting exchanges of technologies and experiences with other countries.

According to the Agriculture Ministry, as of 2008, the number of rural households using biogas in China was 30.5 million.

A total of 12.2 billion cubic meters of methane was produced per year by the household methane pools and 39,500 large biogas projects, which process livestock excrement and other agricultural waste into the gas.

The total methane burnt in the rural areas is equivalent to 18.5 million tonnes of coal, which would produce more than 45 million tonnes of carbon dioxide.

However, methane's market value for the carbon trade is still new to many Chinese.

"When Zhongshui company came to us to discuss the CDM project in March, we had never heard of it and thought they were swindlers," said Liu Gaoxiang, deputy director general of Kaiyang's Agriculture Bureau.

China has quickly become an active player in the global CDM market.

According to the National Development and Reform Commission (NDRC), as of October, 663 Chinese CDM programs had been successfully registered with the UN CDM Executive Board with an anticipated quota of carbon dioxide emissions reductions of 190 million tonnes per year.

Chinese programs account for 58 percent of the world's total registered CDM projects.

Experts believe both the developed and developing countries could benefit from the carbon trade.

Particularly, the developing countries could acquire funds and technologies for further greenhouse gas emissions reductions.

He Junyuan says China's mid-west rural areas have great potential for reducing greenhouse gas emissions by developing small renewable energy programs, such as hydro-electricity, wind power and methane, in which farmers frequently encounter difficulties in money and technologies.

The carbon trade is a good mechanism, He says, but the problem is when and how much the developed countries would buy the emission reduction quota.

Some methane programs of Kaiyang are being voluntarily listed at the Chicago Climate Exchange, He said. However, "due to some political and economic reasons before the Copenhagen conference, the carbon trade price at the exchange has sharply dropped from 6 dollars per tonne to about 0.1 dollar, and trading in recent months has almost ceased."

The fate of the CDM is on the agenda of leaders and representatives from 192 countries and regions at the Copenhagen conference.

People like Ai Xinglong and He Junyuan are eager to know how the developed countries will provide funds and technologies to help developing nations to adjust to and mitigate climate change after the Kyoto Protocol expires in 2012.

Ai Xinglong wants his voice to be heard: "We contribute to the reduction of greenhouse gas emissions so we deserve some compensation."