China Grapples With A Burning Question
Two new projects, one in Inner Mongolia and the other in Tianjin, mark the coal-hungry country's first major steps toward trapping carbon emissions
Appeared in Science Magazine, September 28, 2009
By Josh Fenn
In the coming weeks, on the plains of Inner Mongolia, China plans to launch its first large-scale effort to capture and store carbon emissions. A new coal-to-liquid plant in Erdos will burn coal to make, at the outset, a little over 1 million metric tons per year of diesel and other petrochemicals. Operated by China's biggest coal producer, Shenhua Group, the plant will generate as a byproduct about 3.6 million tons of carbon dioxide (CO2) a year. In an effort to make carbon capture pay, much of the gas will be sequestered in nearby oil reservoirs, where pressure from the CO2 will force hard-to-get oil to the surface.
Shenhua's plant is one of two pivotal carbon capture and storage efforts in China. The other is GreenGen, an integrated gasification combined cycle (IGCC) plant that the Chinese government approved last June for construction in Tianjin. Instead of pulverizing coal as a conventional power plant does, IGCC plants turn it into gas, which allows for easy separation of CO2 from combustible gases—and far easier CO2 capture. If successful, GreenGen could redefine how power is generated from coal in China, says Richard Morse of the Program on Energy and Sustainable Development at Stanford University in Palo Alto, California. "You could make a very strong case that it's the leading carbon-capture project for coal-fired power in the world," he says.
As China's economy booms, the need for carbon capture and storage is becoming increasingly urgent. Electricity consumption has shot up more than 50% in the past 5 years, and the country uses nearly 200 million more tons of oil per year than it did 10 years ago. For the next half-century or so, experts say, China will likely have to rely on coal to meet most of its energy needs. Carbon capture and storage technologies may require steep investments, but they are a must to stem environmental deterioration, says Simon Hayles, a bioenergy and carbon-capture project manager at the energy and environment consultancy AEA in Oxford, U.K.
A perennial question in China as elsewhere is how to offset the costs of carbon capture. One approach is to make use of CO2 above ground. Last year, Huaneng Group, China's biggest electricity provider, and Australia's Commonwealth Scientific and Industrial Research Organisation commissioned a coal-burning power plant in suburban Beijing capable of capturing 3000 tons of CO2 per year. The gas is sold to local softdrink manufacturers to put the fizz in carbonated beverages. Huaneng plans to scale up with its Shidongkou No. 2 Power Plant carbon capture project, a suite of carbon-capture facilities to be added to an existing coal plant in Shanghai. Expected to be operational by the end of 2009, the project will capture roughly 100,000 tons of CO2 per year and sell the gas to soda companies and other local industries.
But such industries can put to use only a tiny fraction of CO2 emissions. That's why China is turning to enhanced oil recovery for carbon capture, says Deborah Seligsohn, principal adviser of the World Resources Institute's Beijing office. PetroChina has in the past used water and various polymers to recover oil in the country's northeast, she says. The Erdos plant shifts the emphasis to carbon sequestration. It will eliminate an intermediate gas-producing step used by other coal-to-liquid plants and use a relatively pure stream of CO2 for oil recovery.
Experts are even more enthusiastic about Tianjin's GreenGen project. The plant will skim off CO2 from gasified coal before it is burned, a huge increase in efficiency compared with older plants that attempt to sop up CO2 from emissions after combustion. In the long run, IGCC could be an economic boon—and China has a head start on the competition, says Morse. "IGCC is likely to be the most viable path forward for carbon capture on coal plants in China," he says.
By 2011, GreenGen is expected to be running at a capacity of 250 megawatts of electricity, says Liu Yu, a GreenGen research engineer. An additional 450-megawatt facility able to capture more than 1 million tons of CO2 emissions per year will be completed by 2016, says Yu. The likeliest use of the CO2, experts say, is enhanced oil recovery.
Fortunately, China has plenty of places to sock away CO2. According to a preliminary report by geologist Li Xiao Chun of the Chinese Academy of Sciences Institute of Rock and Soil Mechanics in Wuhan, China has some 46 natural gas and oil reservoirs, 68 coal beds, and 24 saline aquifers that could be used to sequester CO2. That equates to a CO2 storage capacity of some 3.2 trillion tons, Li says. If it's economically feasible to store carbon even in only 10% of these formations, he says, China could tuck away a century's worth of emissions before running out of space.
Major sequestration efforts in China— such as funneling tens of millions of tons of CO2 into reservoirs or aquifers—are years away. But with key carbon capture and storage projects finally getting off the ground, China could soon be breathing at least a little bit easier.