Optimal configuration of integrated energy system considering heat enhancement and combined operation of low head seawater pumped storage and reverse osmosis

Abstract

The remote coastal areas face difficulties due to energy shortages and insufficient freshwater resources. To reduce the energy consumption of reverse osmosis desalination in coastal areas, this paper proposes an optimal configuration method of integrated energy system considering heat enhancement and combined operation of low-head seawater pumped storage and reverse osmosis. Firstly, the heat analysis of power to gas and the construction of the reverse osmosis temperature model considering heat enhancement are carried out, utilizing its reaction heat to preheat the reverse osmosis feed. Secondly, the reverse osmosis feed is supplied from the upper reservoir of the low-head seawater pumped storage, allowing the operating pressure of the reverse osmosis to be met by both the hydrostatic pressure of the upper reservoir and the high-pressure pump. Furthermore, the working efficiency of the reversible turbine is modeled by considering the operational characteristics of the seawater pumped storage. Then, a bi-level mixed-integer optimal configuration model with annual total cost and wind abandonment rate as evaluation indexes is established and solved. The results indicate that compared to the conventional system, the proposed system achieves a reduction of 4.30 % in annual total cost and 2.46 % in wind abandonment rate, resulting in more pronounced economic advantages and higher renewable energy utilization. Furthermore, the energy consumption of reverse osmosis is decreased by 26.62 %, and the energy utilization ratio of the seawater pumped storage is increased by 9.81 %, demonstrating superior performance in system energy efficiency.