Co-optimization of water and power systems’ long-term expansion planning in arid regions with desalination plants providing water to high-altitude demand points

Abstract

Within the context of the increasing reliance on desalination to meet water demands, particularly in arid regions, a cost-effective solution is the adoption of integrated water supply systems, shared by several users. Recognizing the strong relationships between water and power systems, we propose a comprehensive water and power system’s co-optimization long-term expansion planning model and use it to measure the level of readiness of the systems to face significant electricity and/or water demand increments. The proposed model addresses complex real-life phenomena, including congestion and flow limits in power transmission lines, decentralized power generation and desalinated water production with various technologies, seasonality, power capacity factors of variable renewable energy, and friction losses in pipelines, while considering an hourly resolution to better represent the behavior of the water and power systems. A case study is conducted in a Chilean region characterized by water scarcity, abundant renewable potential, and high-altitude demand points. Our case-study results show that, even when co-optimizing desalinated seawater and power networks expansion planning, the level of readiness of the systems to address large desalinated water demand increments by 2030 can be quite limited compared to the readiness to address electricity demand increments. By 2050, desalination process’ electricity consumption could represent up to 17% of the total electricity demand in the region studied, highlighting the need for effective public policies to address this emerging challenge. In addition, results show that considering friction losses in the expansion planning of desalinated seawater and power networks greatly influences the size and the timing of infrastructure investment decisions, although it may not have a significant impact on total costs or electricity consumption.