Cooling Systems for Power Plants in an Energy-Water Nexus Era

Abstract

Potable water is becoming scarce in many areas of the planet as the human population pushes past 7 billion. There is an increasing need for electric power since electricity is essential for modern development and progress. Traditionally, condenser cooling systems for power plants use seawater or freshwater in conjunction with cooling tower technology. Seawater is used in plants near the sea or ocean, and seawater condenser cooling systems are typically open systems. More recently, air-cooling has been implemented and undergoing evaluations. Predictably, during the summer season in hot, semi-desert and desert areas, air-cooling would not prove very efficient. Ironically, these areas would require the most fresh, potable water if the population and/or population density is large. The need for additional power generation units to satisfy consumer demands, and hence more cooling capacities, creates a problem for utilities. The current work researches the feasibility of using seawater cooling systems in the USA that are far from the sea. Five such locations have been identified as possibilities. Such a system has proven successful in South Florida. This system utilizes a series of cooling canals, used to dissipate the condenser heat to the surroundings. Relevant statistics of such a canal include water flow rate, total capacity, and MW of generators (both fossil-fueled and nuclear steam generators) the system is designed to cool. Additional statistics include the possible need to top-up (both amount and frequency of water required to maintain canal surface levels) or whether local natural rain water is adequate to replace evaporation and loss. Logistical information includes the estimated size of land required to accommodate the cooling canals. In estimating the canal system size and concomitantly the land required in other parts of the country, there is the tacit assumption that the thermal capacity of the surrounding land is about the same, and that the thermal conductivities of the different types of soil, and the heat transfer coefficients between the seawater and the canal are similar.