Could chicken waste help power China?
Housed in series of buildings with red roofs, a massive poultry farm outside Beijing is home to three million chickens.
The birds are stacked in racks from the floor to the ceiling and produce almost half a billion eggs every year.
The eggs are packaged at the Deqingyuan farm and then shipped to supermarkets across the capital, where the farm provides 70% of Beijing's supplies.
But eggs are not the only product that these chickens create.
Every day they generate 212 tonnes of chicken manure, releasing an overpowering stench.
Instead of letting this go to waste, however, this farm sees it as an opportunity.New sources
The chicken manure drops onto a conveyor belt, which takes it to a processing plant.
Methane gas is then extracted from the manure to generate electricity, which is sold to the national grid. The remaining manure is then turned into fertiliser.
Vice-President of Deqingyuan Agricultural Technology Company Pan Wenzhi says projects like this are hugely important.
"We're a developing country but our coal and gas supplies will run out in the next few decades," he said. "It's very important for China to exploit new sources of energy."
By generating bio-gas, the farm is part of China's search for a more sustainable blueprint for its economic development.
The company is planning to open several other plants in different parts of China.'Sustainable growth'
As the world's largest energy consumer and emitter of greenhouse gases, Beijing will play a critical role if global warming is to be effectively addressed.
China relies on coal for about 70% of its energy supplies in order to fuel its economic boom.
End Quote He Fujing Farmer
Everyone wants their children to be healthy, but it's up to the government to deal with this issue”
But the country's breakneck growth has caused enormous damage to the environment.
Beijing has plans to curb its reliance on fossil fuels, although overall energy demands are rising rapidly.
By 2020, authorities say that 15% of China's energy supply should be provided by non-fossil fuels such as solar and wind power, and hydro-electric dams.
But many environmental experts say the government most do more.
"Protecting the environment is not just about controlling pollution," said Yu Jie, a policy director for China's branch of The Nature Conservancy organisation.
"It needs to be linked to the country's economic growth. Only that way can we get sustainable growth."
But for now, the authorities are prioritising the economy.
The dilemma they face is illustrated by one family living close to the huge chicken farm.
He Fujing, 39, and his wife and daughter lead a simple life. They use the methane gas produced from the chickens to cook the vegetables they grow in their garden.
But Mr He, a farmer, dreams of owning a car and apartment in the city. At the same time, he worries about the impact pollution will have on his six-year-old daughter.
"I worry about the water quality here," he said, standing in his vegetable patch. "Everyone wants their children to be healthy. But it's up to the government to deal with this issue."
China remains a developing country, and the authorities maintain it must improve the quality of people's lives. But increasingly, it is the environment that is paying a high price.