Dry, hybrid cooling now accounts for 3 percent of US thermoelectric generating capacity

Three percent of U.S. thermoelectric generating capacity now uses dry and hybrid cooling, most of which had begun operation since 2000, the U.S. Energy Information Administration (EIA) said in a recent report.

Dry cooling systems use ambient air, rather than water, to cool and condense steam. They can be classified as direct and indirect systems. Direct dry cooling systems condense steam using ambient air and do not consume any water. Indirect dry cooling systems use conventional water-cooled condensers to condense steam but keep the cooling water in a closed system, so no water is lost to evaporation and very little water is used.

Hybrid cooling systems use a mix between dry and wet cooling and can use both water and air to condense steam. During cooler seasons, they typically operate as dry cooling systems. During hotter seasons when dry systems have lower efficiency, they use wet cooling.

There are 83 plants that operate dry and hybrid cooling systems in the United States, EIS said. These plants support approximately 20 gigawatts (GW) of steam-generating capacity. California has the highest number of plants with dry cooling systems at 13, and Texas has the most dry cooling capacity at 2.8 GW, closely followed by Virginia with 2.4 GW.

More than 83 percent of dry and hybrid cooling capacity comes from natural gas combined cycle (NGCC) plants. The amount of cooling needed for natural gas combined-cycle plants is much less per megawatt-hour than for coal or nuclear plants. Dry cooling may also be an attractive option for concentrated solar power systems, EIA noted.