University of Maryland (UMD)

In thermoelectric power generation, only about 40% of the energy in the fuel is converted into electricity. In other words, the power plant operates at about 40% efficiency. The remainder of the energy is converted to low-grade waste heat that must be removed to maintain the power plant’s efficiency. Most power plants use water from nearby rivers, lakes, or the ocean for cooling. The water may pass directly over tubes containing the plant’s heated condenser water, and then be returned, warmer, to the original source, or it may be evaporated to carry off the heat in water vapor. In areas with limited water or under drought conditions, dry-cooling systems use air to remove heat from the plant’s condenser water. However, present dry-cooling technology reduces the power plant’s efficiency and requires costly equipment. With water supplies becoming increasingly strained in many areas, economical dry-cooling approaches that do not reduce the efficiency of power plans are critically needed. Innovative methods to allow cooling below the daytime ambient air temperature and improve heat exchange between air and the plant’s recirculating condenser water will provide the keys to ensuring the continued efficiency of power generation while decreasing the burden on water supplies.

The University of Maryland (UMD) and its partners will utilize a novel microemulsion absorbent, recently developed by UMD researchers, for use in an absorption cooling system that can provide supplemental dry cooling for power plants. These unique absorbents require much less heat to drive the process than conventional absorption materials. To remove heat and cool condenser water, microemulsion absorbents take in water vapor (refrigerant) and release the water as liquid during desorption without vaporization or boiling. UMD’s technology will use waste heat from the power plant’s flue gas to drive the cooling system, eliminating the need for an additional power source. The design will improve upon the efficiency of commercially available chillers by 300%, even though the cost and size of UMD’s technology is smaller. The indirect, absorption cooling system will lower condenser water temperatures to below the ambient temperature, which will ensure the efficiency of power plant electricity production.

If successful, UMD and its partners will develop a significantly improved absorption cooling system that can provide supplemental cooling to power plants without consuming water.