Relationship between Water Use and Energy Generation from Different Power Generation Types in a Megacity Facing Water Shortages: A Case Study in Shenzhen

Abstract

Using less water to generate more power is a goal of the worldwide power industry, but this is difficult to achieve because of the lack of long-term, operational data-based studies. This challenge is especially severe for megacities facing water shortages. This study used long-term data (2005–2015) from Shenzhen, a megacity of over 20 million people that faces severe water shortages, to determine the relationship between water and energy for different types of power generation. It was found that power generation consumed huge amounts of water and that cooling water was the biggest water use category. Smaller power plants, such as the Yueliangwan power plant, which uses the closed cooling method, consume 2.36 million m3 of tap water per year, equivalent to the water supply of a small reservoir. However, larger power plants, such as the Mawan power plant and Dayawan nuclear power plant (using the open cooling method), use 0.92 and 3.42 billion m3 of seawater for cooling every year, respectively, equivalent to about 60% and 200% of the total annual water supply in Shenzhen, respectively. Therefore, large thermal power plants and nuclear power plants should be built in coastal areas with rich water resources rather than in arid or semi-arid areas. Additionally, the water use efficiency of nuclear power plants was found to be 0.22 m3/kWh, which was significantly lower than that of coal-fired power plants (0.10 m3/kWh) and gas-fired power plants (0.09 m3/kWh). Third, the water use efficiency of the closed cooling method was ten times higher than that of the open cooling method. Therefore, the closed cooling method is suitable for power plants constructed in areas without rich water resources. These results are useful for balancing the water and energy demands in the changing world.