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September 29, 2009

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This pile of manure is gold

Just think of the foul, methane-rich manure produced by 5 million chickens. Don't turn up your nose. That's a lot of green biofuel. Zhang Qian gets a whiff. Feeding plants to farm animals and using animal manure to fertilize plants is an environmentally friendly, but old-fashioned way to farm today.

But generating biogas - especially flammable methane gas - from manure and organic waste and using that to generate electricity is far better and tackles air, water and ground pollution.

Furthermore, methane is a polluting greenhouse gas, and using it for power eliminates it from the atmosphere.

China is known for using biogas in the agricultural and small community sector and many rural households use digesters for organic matter to generate power.

Expansion of biogas use is underway as China develops alternative forms of energy.

A major power plant in Penglai city of northern China's Shandong Province uses manure from 5 million chickens to produce electricity for the grid. It went into operate late last month.

In the showcase Shandong plant, chicken manure and waste water from farms are sent to a biomass anaerobic digester and storage facility, which first generates methane.

The gas is then used to generate power that is sent to the grid; the leftover manure and waste is used as organic fertilizer and is given away to farmers.

The new plant of 3-megawatt-installed capacity can produce about 10 million cubic meters of biogas each year, generating about 20 million kwh and 0.3 million tons of organic fertilizer.

Around 50 similar plants using animal manure are operating in China. Only a few can produce more than 1 megawatt - including the new Shandong plant and one in suburban Beijing completed in 2007, according to Pui Wing Leung, deputy general manager of Jebsen Industrial. A third is operating in Fujian Province.

Jebsen is a marketing and distribution organization that cooperated with General Electric's Energy's Jenbacher Gas Engine Division. GE and Jebsen cooperated with the Beijing Deqingyuan Agricultural Technology Co and Shandong Minhe Farm Co.

"Animal manure contains a lot of organic material that produces methane as it decomposes naturally," says Leung. "It pollutes the air if it isn't treated, but it can provide a huge amount of energy that we can use."

The methane from the manure of one adult chicken can produce about 7.2 kilowatt hours of electricity and 6,000 kilocalories of heat energy over one year.

But all that waste from one chicken can also pollute the air, the water and the soil.

The idea of generating energy from animal manure first appeared in Europe as a positive way of preventing water, air and ground pollution.

"At first we could easily sell manure when we started with small-scale chicken farms in 2002," says Gu Qing, spokesman of Deqingyuan Co. "But when we had 2 million chickens in our farm in 2006, there were 150 tons of manure and 100 tons of waste water produced every day.

"It was a big problem. Though we could still sell some as fertilizer, the manure and water- polluted land and water and transport was a problem," Gu says.

To solve the problem, the company became a pioneer in combining power generation with poultry farming in 2006-07. The result greatly reduces ground, water and air pollution.

The biogas plant in Shandong Province generates around 40,000 kilowatt hours of electricity every day; the company sells it to the national electricity grid and buys power as needed.

China's Renewable Energy Law says the biofuel plant can sell the electricity for 0.25 yuan higher than the power generated in traditional ways (like coal burning), but it can purchase electricity at the traditional price of about 0.5 yuan per kilowatt hour for farms in Shandong. The price differential means the company can earn around 8 million yuan (US$1.2 million) each year.

In the global carbon-trading system, the company can also sell its pollution discharge reduction index to developed countries for 9 euros (US$13) per ton. The annual 95,0000-ton carbon dioxide discharge reduction earns the company another 8 million yuan.

The power plant of Minhe Co in Shandong can also earn 1.2 million yuan a year by producing 20 million kilowatt hours of electricity, plus 6 million yuan in carbon trading for 66,000 tons of carbon dioxide discharge reduction, according to Leung.

Though biofuel is efficient and makes sense, it still needs a lot of manure and needs economies of scale, around 1 million chickens, 50,000 pigs or 10,000 cows to make a power plant viable.

But farms in China are scattered, the national grid needs improvement to accept inward flows of power, and there still isn't great demand for organic fertilizer.


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