Abordagem para o balanço energético em aproveitamentos hidroagrícolas

A comprehensive performance assessment system for diagnosis and decision-support to improve water and energy efficiency and its demonstration in Portuguese collective irrigation systems

“…In contrast, service interruption with a duration higher than one day and independent of the cause (internal or external to the CIS) should be considered to calculate service interruptions (AH19). Besides assessing pump equipment efficiency (AH15), the energy supplied in excess (AH16) requires energy balance calculation (Cunha et al, 2019b). It includes the energy associated with water losses, inefficiencies in pumping stations and hydraulic turbines, continuous and singular head losses, and the surplus energy delivered (relevant in the case of pressurised irrigation systems).…”

“…Before diagnosis, data collection is carried out according to the variables required in the water utility profile (Table 1), the CIS profile (Table 2) and the PIs that integrate the PAS (Table 3) for global system analysis. Since the focus is on improving water and energy efficiency, the calculation of several PIs (AH04, AH09, AH10, AH11, AH14, AH15 and AH16) requires a prior calculation of the annual water and energy balances (Cunha et al, 2019a(Cunha et al, , 2019b.…”

“…Existing PIs for CISs do not consider water loss components (e.g., evaporation, real losses due to discharges and leakage, metering errors) and the energy inefficiency components (e.g., pump and hydropower inefficiencies, energy dissipated due to water and head losses) that occur throughout the network until the water intakes (i.e., point of delivery to users). Recent contributions to water and energy balance for collective irrigation systems allow estimating these components during the irrigation period and enable the calculation of new PIs (Cunha et al, 2019a(Cunha et al, , 2019b. The water balance (Cunha et al, 2019a) estimates billed authorised consumption and non-revenue components (i.e., the volume associated with unbilled authorised consumption, evaporation losses, apparent losses, and real losses) relative to system input volume.…”

“…Apparent losses include inaccuracies related to users' metering and unauthorised consumption, whereas real losses include canal and pipe leakage and discharges in canals and intermediate reservoirs. The energy balance (Cunha et al, 2019b;Mamade et al, 2017) allows for estimating the minimum required energy to ensure the service to users and energy supplied in excess relative to system input energy (i.e., natural, shaft input energy). The energy supplied in excess may be associated with water losses, dissipated due to head losses or energy inefficiencies in pumping stations or hydraulic turbines.…”