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.
Project Innovation + Advantages:
General Electric (GE) Global Research will design, manufacture, and test an absorption heat pump that can be used for supplemental dry cooling at thermoelectric power plants. The team’s project features a novel, absorbent-enabled regenerator that doubles the coefficient of performance of conventional absorption heat pumps. The new absorbents demonstrate greater hygroscopic potential, or the ability to prevent evaporation. To remove heat and cool condenser water, these absorbents take in water vapor (refrigerant) and release the water as liquid during desorption without vaporization or boiling. GE’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. GE estimates the system will cost half that of conventional absorption heat pumps.
If successful, GE will develop an improved absorption heat pump that significantly increases the effectiveness of absorption heat pumps, but at a much lower cost.
Power plants can maintain energy efficiency by using the team’s dry-cooling technology instead of water cooling when water use is restricted.
The team’s system results in negligible net water use, and therefore can eliminate the need for local water resources for cooling and help conserve water for other uses.
GE estimates that the cost of its system will be 50% less than conventional absorption heat pumps on the market today, which could accelerate the adoption of dry-cooling technologies.