While China's desire to end its dependence on foreign oil is helping to drive huge capital investments in liquefaction technology, the country's power producers are moving much more slowly to take advantage of coal gasification. What they, like their American counterparts, are missing is an incentive to upgrade from conventional pulverized-coal plants to the more expensive gasification plants. According to Li Wenhua, the former 863 program manager (who now directs gasification research in China for General Electric), Chinese industrialists perceive pulverized-coal plants as a license to print money. "People say you shouldn't call it a power plant; it's a money-making machine," says Li. As yet, no power company has been willing to be the first to hit the off switch.
Ironically, China's move to a more open economy has hampered efforts to deploy more innovative technologies. In the 1990s, it looked as if China's power sector was headed for its own gasification revolution. In 1993, China's leading power engineering firm, China Power Engineering Consulting in Beijing, began designing the country's first gasification power plant. The monopoly utility of the era, the State Power Corporation, planned to build the commercial-scale plant in Yantai, a thriving seaport not far from the Bohai Sea. The Yantai plant was to be the beginning of a transition to cleaner coal technology, says Zhao Jie, the plant's designer, now vice president of China Power Engineering. "China wanted to take a cleaner and more efficient way to produce power," says Zhao. Instead, the demonstration plant she designed went on a roller-coaster ride to nowhere. Design work was temporarily halted in 1994 when the cost of the technology was deemed unacceptably high, revived in the late 1990s, and then cut adrift after 2002 by the breakup of the State Power Corporation.
The Yantai power plant was based on integrated gasification combined cycle (IGCC) technology. IGCC plants resemble natural-gas-fired power plants--they use two turbines to capture mechanical and heat energy from expanding combustion gases--but are fueled with syngas from an integrated coal gasification plant. They're not emissions free, but their gas streams are more concentrated, so the sulfurous soot, carbon dioxide, and other pollutants they generate are easier to separate and capture. Of course, once the carbon dioxide--the main greenhouse gas--is captured, engineers still need to find a place to stow it. The most promising strategy is to sequester it deep within saline aquifers and oil reservoirs. In preliminary analyses, Chinese geologists have estimated that aging oil fields and aquifers could absorb more than a trillion tons of carbon dioxide--more than China's coal-fired plants would emit, at their current rate, for hundreds of years.
The Huaneng Group, a power producer based in Beijing, has pulled together a consortium of power and coal interests (Shenhua included) called GreenGen to build the first Chinese IGCC demo plant by 2010; like the related FutureGen project organized by the U.S. Department of Energy, GreenGen is to start with power production, then add carbon capture and storage. China's vice premier, Zeng Peiyan, made an appearance at GreenGen's ceremonial debut last summer, indicating Beijing's support for the project.
The problem is that IGCC plants still cost about 10 percent to 20 percent more per megawatt than pulverized-coal-fired power plants. (And that's without carbon dioxide capture.) China's power producers--much like their counterparts in the United States and Europe--are waiting for a financial or political reason to make the switch. In part, what's been missing is regulation that penalizes conventional coal plants. And China's environmental agencies lack the resources and power to make companies comply even with regulations already on the books. Top officials in Beijing admit that their edicts are widely ignored, as new power plants are erected without environmental assessments and, according to some sources, without required equipment for pollution control.
Even advocates of IGCC technology expect that its widespread deployment in China will take at least another decade. Indeed, Du Minghua, a director for coal chemistry at the Chinese Coal Research Institute, predicts that it will be 2020 before application of IGCC technology begins in earnest.
Waiting to Inhale
Despite such pessimistic predictions, China's vast experience with advanced coal technologies and its proven ability to implement new technologies at a startling pace provide ample room for optimism. When you're racing into Shanghai at one-third the speed of sound on a train supported by an electromagnetic force field, it's hard to believe that a country capable of such an engineering feat will continue to ignore the deadly pollution engulfing its cities.
To some analysts, the switch to clean-coal technology seems almost inevitable. "China has to rely on coal for future electricity and fuel needs, and it will eventually have to cap its CO2 emissions," says Guodong Sun, a technology policy expert at New York's Stony Brook University who has advised the Chinese government on energy policy. "Gasification is one of a very few technologies that can reconcile those conflicting scenarios at reasonable cost."
Still, the timing of such a technology transition is very much in question. Will China really wait until 2020 to start the process of cleaning up its coal-fired power plants? The answer will depend, ultimately, on when China begins to feel that using coal gasification to generate electricity is as urgent as using it to produce transportation fuels--when the costs of air pollution become as worrisome as the costs of relying on foreign oil.
Source : Technology Review
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Rédigé par : used computers | 27 janvier 2010 à 14:16