By David H. Pai

China's massive dependence on coal has raised a number of questions regarding its use in the future, especially in terms of the environmental difficulties caused by the fuel. The nation's large coal reserves, more than 130 billion tons, ranks third in the world behind the former Soviet Union and the United States. Coal accounts for 77 percent of the total energy needs of China, which is the world's largest producer and consumer of the fuel. Current plans call for production of 1.6 billion tons by 2000 and a projected 2.2 billion tons by 2010.

Even with its abundance of coal, its use suffers the classic ills of inefficiency and high pollution. The average efficiency of Chinese power plants is approximately 26 percent. Some of the more significant reasons include fuel variability (which prevents boilers from operating at optimum efficiency), antiquated designs, and poor maintenance. Because China generally lacks emission-cleanup devices, the nation ranks second in the world (behind the United States) in carbon dioxide production. The 773 million tons generated annually accounts for the dominant share of pollutants in Asia and 12 percent of the world's total. Therefore, these environmental problems are not only a Chinese problem but a global one as well.

At both the central-government and provincial levels, there is an increasing desire to correct the situation. Yet power demands are so severe that cost pressures will play a major role in deciding how much environmental-cleanup equipment will ever be installed by China. Given limited funds, a government official once asked, would you buy three power plants with scrubbers or four without when faced with scheduled blackouts for key factories? This question, of course, has no easy answer.

One possible solution is the application of circulating-fluidized-bed (CFB) technology to utility-size plants. This type of system takes advantage of enhanced heat and mass transfer when solids are fluidized as they undergo combustion. In CFB systems, crushed coal and limestone are fluidized by heated air. The resulting combustion process is highly mixed, and the calcium in the limestone reacts with the sulfur in the coal, thus desulfurizing the coal by forming calcium sulfate as part of the ash.

This type of boiler also operates at a substantially lower temperature—approximately 1,600°F, compared with the 3,000°F flame in a conventional pulverized-coal boiler—suppressing nitrogen oxide formation. Because fluidization promotes mixing and heat-and-mass transfer, this type of boiler can also burn a wider variety of coals in an optimum manner.

The technology of fluidized beds was first used in the chemical industry. Its superior environmental performance when applied to coal combustion makes it particularly attractive in places such as China, with its large variety of coal types including low-grade, difficult-to-burn coal. The challenge is to scale these units up to utility sizes (300 megawatts or larger) at costs competitive with pulverized-coal units. Success in this effort appears to be near.

China will build coal-fired power plants near its vast coal mines in remote regions with power to be shipped "by wire" to population centers in the eastern provinces. For example, power generated in the central province of Shanxi will be sent east to Jiangsu, which includes the city of Shanghai.

The drive to increase efficiency is expected to intensify in the future. Higher efficiency means lower coal and fewer transportation requirements. From a global-climate perspective, it will also mean lower carbon dioxide emissions. In the next generation of technological innovation, the most likely candidates are pressurized-CFB and integrated-gasification combined-cycle (IGCC) systems.

A pressurized-CFB system is compact, has excellent potential for low capital cost, and is very suitable for repowering. An advanced, or topping, pressurized-CFB system combines a partial gasification system with a pressurized CFB to attain ultrahigh efficiencies. Foster Wheeler Development Corp. in Livingston, N.J., was recently invited to demonstrate this technology in a 160-megawatt station in Lakeland, Fla.

With IGCC systems, a 100-megawatt unit has been demonstrated already, and a 250-megawatt system is ready for demonstration. These advanced systems will have efficiencies greater than 45 percent, compared with today's conventional Rankine-cycle systems, which have 35- to 36-percent efficiencies. The U.S. Department of Energy's Clean Coal Program is actively supporting the demonstration of these advanced systems. The technology will undoubtedly prove technically feasible; the challenge is to attain the reliability and competitive cost for commercialization.

Coal for power generation accounts for only 31 percent of China's consumption; industrial use, which is likewise very inefficient, accounts for the bulk of the remainder. For example, many fixed-bed gasifiers, used for coke-oven applications and town-gas production, are low-efficiency, high-emission devices. The Asian Development Bank is helping to introduce the next generation of gasifiers and upgrade the existing ones.

Power needs in China are projected to grow from 210 gigawatts in 1995 to 300 gigawatts in 2000, with a great majority of the new plants to be coal-fired. Unfortunately, most coal mines are located far from China's population centers. The transportation of coal from the mines to the eastern population centers, where additional power is needed, presents a formidable challenge, especially because the railroad system is already hard pressed.

Thus, a high-priority goal is to ship coal by wire. This policy will have the added benefit of atmospheric dispersion of pollutants, with power plants sited away from densely populated areas (but this is hardly an ultimate solution to the pollution problem). Last fall, Foster Wheeler received an order to supply six boilers, each producing 350 megawatts and firing anthracite coal, to be sited at Yang Cheng in Shanxi province, at the mine's mouth. The power of this 2,100-megawatt station is destined for Shanghai and the lower Yangtze industrial region. The pressure to sustain growth will result in many more coal-by-wire projects.

Coal will continue to play an increasingly important role in China's energy needs. From a business and investment viewpoint, the nation does not have nearly enough foreign reserves to purchase the bulk of the needed plants and facilities. Joint ventures, local manufacturing, and technology transfer will remain prerequisites for long-term business relationships with China.

David H. Pai is chairman and president of Foster Wheeler Development Corp. in Livingston, N.J.


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