Effects of a Floating Photovoltaic System on the Water Evaporation Rate in the Passaúna Reservoir.

Abstract

Freshwater scarcity is a significant concern due to climate change in some regions of Brazil. Water evaporation rates in reservoirs increase with increasing temperatures, which can represent a great challenge for managing water resources. The coverage area of floating photovoltaic systems reduces the amount of sunlight on the water surface, reducing the water evaporation rates. In 2019 a floating photovoltaic system was installed in the Passaúna reservoir, located in the metropolitan region of Curitiba, State of Paraná, southern Brazil. The general objective of this work is to study the effects of the floating photovoltaic system in the Passaúna reservoir on water evaporation. Based on this objective, the work was divided into two chapters: in the first chapter, the evaporation avoided by the installation of the floating photovoltaic system in the Passaúna reservoir was estimated, considering the existing coverage area, with a capacity of 130 kWp, and expansions of the system to correspond to energy production capacities of 1 MWp, 2.5 MWp and 5 MWp. Different methods were used to estimate the evaporation rates through local meteorological data such as air temperature, humidity, solar radiation, and wind speed, whose results were compared with direct evaporation measurements obtained at the nearest meteorological station. The FAO Penman-Monteith and Linacre method (1977) showed better results for the region. An efficiency of 60.20% in reducing evaporation rates and water-saving by the floating photovoltaic system layout was obtained, which was then used to calculate avoided evaporation volumes, assuming the increases in coverage area and its relationship to energy production capacity, considering the reservoir at full capacity and in the current scenario of water drought. In the second chapter, evaporation rates were estimated for future climate scenarios for the years 2040, 2060, 2080, and 2100 considering the climate change scenarios from the Intergovernmental Panel on Climate Change. PGECLIMA_R software was used to simulate air temperature, humidity, and solar radiation; the wind was obtained through a beta distribution simulation. An increase in evaporation of 31.88% compared to current historical data can be expected towards the end of the century in the worst climate scenario. Therefore, technologies such as the floating photovoltaic system can represent an essential alternative in preventing evaporation today and in the future, becoming a strategic tool in managing water resources.