Many plants are being forced by changing environmental laws and public pressure to retrofit existing power generating facilities to closed-circuit cooling water systems or even dry cooling options rather than continue with once-through river or ocean cooling water. In arid regions in particular, there just isn’t enough water available to simultaneously satisfy the needs of power plants and people. (See
POWER, January 2008,
“Costlier, scarcer supplies dictate making thermal plants less thirsty.”)
The pragmatic developer may also select dry cooling early in a project because it increases plant siting options and its use can significantly accelerate approval of construction permits because water use issues are taken off the table. Shortening a project schedule by even six months can completely change the economics of a project and easily balance the increased capital cost of dry cooling options.
Dry cooling applications in the U.S. have not been limited to arid regions but have also been specified for plants sited in eastern, northern, and mountain areas where water is typically more abundant (Figure 1). Why is that? In recent years, there are many more reasons to consider dry cooling in general, and the air-cooled condenser (ACC) in particular, than just the lack of available water (see sidebar). For instance, there are strong indicators that dry cooling applications are becoming a standard power plant design option. In fact, even areas with abundant water resources--like England, Ireland, Belgium, Luxemburg, and northern Italy (Figure 2)--are adopting the technology. In fact, the largest combined-cycle plant in Europe is rated at 1,200 MW and uses an air-cooled condenser.
1. Popular choice. Air-cooled condensers have been installed on power plants across North America. Courtesy: SPX Cooling Technologies Inc.
2. Strong European market. An air-cooled condenser was used at the gas-fired 460-MW Bruges Power Plant in Belgium. Courtesy: SPX Cooling Technologies Inc.
China is very concerned about further stressing its water supplies and has adopted dry cooling for many of its new power plants. In fact, China has installed air-cooled condensers on over 35,000 MW of its burgeoning fleet of new plants and has dominated the market in installations over the past several years (Figure 3). Over the past two years, China has purchased an average of one new ACC per month for new coal-fired power plants, with typical capacities of 2 x 300-MW or 2 x 600-MW (Figure 4).
3. Most popular market. This map shows the geographic market distribution for power plants equipped with air-cooled condensers over the past four years in Europe. Courtesy: SPX Cooling Technologies Inc.
4. Growing market. An air-cooled condenser was installed at China’s 2 x 300-MW coal-fired Zhangshan Power Plant. The market for air-cooling equipment in China continues to be very strong thanks to the country’s focus on building coal-fired power plants. Courtesy: SPX Cooling Technologies Inc.
In China, as well for other locations across the world, a plant site no longer has to be located close to a water source if ACC is selected. Instead, the location can be optimized with regard to transmission lines and either gas distribution lines (for combined-cycle plants) or rail lines (for coal-fired plants). In China, solid fuel plants are generally located near coal mines, which explains that country’s recent interest in air cooling.
Finally, the cost of land can be reduced when a lake-, river-, or oceanfront plant site isn’t required.
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