Energy-water nexus for thermal power generation in India: challenges and opportunities

Thermal power generation is economical in the current scenario, but it is a water-intensive process, resulting in a high-water footprint. In this research, life cycle water use (LCWU) was assessed for three coal-based thermal power plant in India. The LCWU was found to be in the range of 2.5 to 3.5 L-kWh(-1). The results of the LCWU of coal-based thermal power plants in India are higher than the global average of 1.75 L-kWh(-1). In order to reduce the dependency on water, air-cooled condenser (ACC) with a novel approach of reducing temperature of air before entering into condenser is purposed using vapour absorption chillers. A 300 MW thermal power plant located in the South India region is chosen to illustrate the application of the proposed system. Initially, waste heat from flue gas is used to run a vapour absorption chiller, and finally a solar-assisted vapour compression chiller is used. Also, in order to utilize large coastal lines in India, an alternate approach of sea water cooling-based thermal power generation is investigated. A 2 MW steam turbine plant utilizing deep sea water is designed and analysed. In seawater cooling system the condenser temperature is reduced, increasing efficiency by 1.9% and power output by 133 kW. It resulted in power generation with multiple benefits, including cooling, desalinated water, and increased plant efficiency. The outcomes of this study provide information on water use in Indian thermal power plants along with its comparative assessment. A study of ACCs and seawater-cooled condensers is also an opportunity to reduce the life-cycle water use in thermal power plants in India.