Defining the optimization strategy for solar energy use in large water distribution networks: A case study from the Valle Inferior irrigation system, Spain

Irrigation modernization in Spain has brought significantly increased energy requirements. To provide the needed power, solar energy is rising in popularity. However, matching the availability of solar energy to irrigation demand remains a challenge. In the Valle Inferior irrigation system, while enough solar energy is produced on an annual basis, only 52 % of the energy consumed for irrigation is from own solar production, mainly due to the practice of night-time irrigation. For this system, this study explores two solar energy optimization scenarios. The first aims to optimize use of own solar energy by adjusting the current 24-h irrigation schedule to 8 or 12 h. The analysis finds that in situations where water availability is limited, this change can enable the annual percentage of own solar energy to be increased to 98 % of the total energy consumed. Nonetheless, such optimization of solar energy use gives rise to difficulties in the system itself, as farmers prefer to irrigate at night. In the second scenario, economic profits are optimized with the sale of excess solar energy. In this scenario, besides water availability and irrigation schedule, the optimum also depends on energy prices. Optimization is thus found to differ, depending on the optimization target, as well as water availability and the irrigation schedule used. This poses new operational challenges for large irrigation system management.