China's breakneck economic growth and soaring energy demand are becoming key factors in global energy use. Louisa Lim explores the human impact of the country's dependence on coal products, as part of the BBC's Planet Under Pressure series.
With his thick smudged glasses and faltering gait, 77-year-old Liu Hongkui makes an unlikely protest leader.
But he has become the catalyst for action among the retired workers who live in his community in the industrial city of Tangshan, 150km east of Beijing.
Just behind their compound is a coke plant, which belches out noxious fumes day and night.
The residents are convinced it is poisoning them, causing respiratory disorders, heart disease and cancer.
They are the victims of China's thirst for any energy it can lay its hands on - with air pollution one of several resulting problems ranging from acid rain to greenhouse gas emissions.
"Most people who die in this area die from cancer," Mr Liu says, reeling off the names of four residents who died of cancer in one month alone.
"Many young people have leukaemia. Many old people have lung cancer or bowel cancer. The by-products from the factory include benzene and phenol. All are toxic and bad for humans."
Mr Liu rolls up his heavy blue workers' trousers to uncover his legs.
They are purple, covered with an itchy rash which he has suffered for years. The doctors have told him it is incurable.
"Around 30 people have the same skin disease. In the summer when the factory chimney pumps out steam, if you wear a short-sleeved shirt, your arms will be covered with this rash," he says.
The residents started petitioning the government seven years ago. Since then the provincial Environmental Protection Bureau has acknowledged the plant to be a serious polluter.
But despite a fine, the factory has continued to pump out pollution, prompting the residents to launch a lawsuit.
The coke plant belches out fumes day and night
The forces arrayed against them are more than just one factory, however.
This coke plant is playing a part in the modernisation whirling through China - one of the world's fastest-expanding economies with GDP growth of more than 9% in the last year.
The plant is a small cog in the supply chain, turning coal into coke which is then used as a key source of heat energy in the steel-making process.
Steel, in turn, is needed for the construction of new roads, buildings, cars and everyday home appliances for China's population - the world's biggest at 1.3bn.
Hungry for progress
The Chinese thirst for development means that coke is becoming an ever more valuable commodity, with one brokerage expecting Chinese demand to push prices up 60% in the next financial year.
This means there is a big market for the product, as well as a clear financial incentive to let polluting plants continue to operate.
The residents estimate that 40,000 people live within 1km of the factory
The residents' lawyer, air pollution expert Liu Xiang, says in his experience these factors often influence the local government's behaviour.
"Often these [polluting] enterprises are the main industries and important taxpayers, so local governments don't want to see these enterprises closed down through court judgements because that would interfere with economic development. Sometimes the pressure [on us lawyers] from the local government is extremely great."
It is a dilemma which underlies China's energy crisis and has wider global implications.
China does not have enough electricity to power its economic boom.
It suffered a record shortage of 30 million kilowatts this year, with many areas facing power cuts.
The International Energy Agency predicts the country will account for more than a fifth of the growth in world energy demand in the next 25 years - and for more than a quarter of the increase in greenhouse gas emissions.
Some two-thirds of the country's power comes from coal and coal products, the cheapest and dirtiest forms of energy.
This exacts a very real human toll - official figures say 400,000 Chinese citizens die a year from diseases related to air pollution, and, according to the World Bank, 16 of the 20 most polluted cities in the world are in China.
Klaus Toepfer, head of the United Nations Environment Programme (Unep), says the struggle to move away from polluting forms of energy is a global challenge.
"The need to use fossil fuel right now is unavoidable," he said. "Globally up to 80% of energy supply comes from fossil fuel.
"What we have to do and can do is change the efficiency in fossil fuel use so we have more energy services from the same amount of coal.
"We have to make clean coal technology. We have to do what we can to fight classic pollutants like sulphur dioxide and mercury, and to capture carbon dioxide emissions."
When it comes to coke, new alternatives and cleaner techniques are being developed, such as a pulverised coal injection process.
China has faced power cuts as energy demand outstrips supply
But Karen Polenske, from Massachusetts Institute of Technology, US, who has been researching coke plants in rural China, says new technologies won't necessarily mean an end to the use of coke.
"In order to industrialise, coke is going to have to play its important role for many years to come. A lot of people say this is going to go away as we are going to have substitutes. But coke is not going to go away."
According to her research, the most polluting type of coke plants in China have largely been closed down, but those factories that have stayed open are producing much more coke than in the past.
However, this may change, as China's Ministry of Commerce has announced it will cut the output of coke by 20% next year in a bid to reduce pollution.
As for the future of the Tangshan plant, all attempts to interview the factory bosses were turned down.
Regardless of the difficulties they've been through, some of the residents are still optimistic about the future, like 48-year-old Zhang Shun.
Speaking under a pseudonym, he said he was now unable to work because he had a heart condition, which he blames on pollution from the plant.
"I still have hope," he says. "We've been in a struggle against the coke factory for the past few years, but these problems are always solved slowly.
"There are so many stories on environmental protection on television and in the press. Everybody thinks it's important nowadays, so I see a light at the end of the tunnel."