EDP operates the Pecém thermoelectric power station located in the Brazilian state of Ceará, built in 2012 to meet the growing demand for electricity, which is very dependent on hydroelectric generation.
Typical of the semi-arid region where it is located, the Brazilian Northeast has always recorded periods of drought over the years. However, the average annual precipitation over 6-year periods has been declining since 1910, reaching its lowest value in the 2012-2017 period.
Due to climate change, the frequency and intensity of drought events is expected to increase, raising pressure on the availability and quality of water resources.
By recognizing the impacts of its operations on the environment and considering water as a strategic resource for its activity, EDP Brasil identified initiatives to reduce its consumption to reduce not only the risk to the business due to restrictions on the water supply (competitive uses, regulatory pressure), but also the costs of water purchase and effluent disposal.
Two measures were implemented in mid-2017 that allow for the reuse of part of the effluents generated in the plant and the increase in the number of cooling cycles using the same volume of water.
Reusing liquid effluents
The cooling circuit uses the largest volume of water in the plant and does not require high quality water. Therefore, the first initiative was to reuse effluents from the secondary effluent treatment plant (ETP) in the cooling towers, from a variety of processes, such as boiler and cooling towers blow-offs and rainwater from the coal yard.
Cool with less water
The second initiative was the addition of chlorine dioxide to the oxidation of organic compounds in the cooling water. A volume of water that previously contributed to 3.5 cycles, started to provide from 12 to 15 cycles, thus increasing the concentration cycles of the cooling towers.
The environment wins. We won.
By December 2018 these measures had saved over 1.2 million cubic metres of water. This saving together with the reduction in the costs associated with the previously rejected effluents reached over 6 million Reais in the same period.
In total, with the initial investments and operating costs of the cooling water treatment and maintenance of the ETP, the implementation of the measures had a positive balance of 2.3 million Reais in the 16 months of operation.
In 2019, 31.5% of the effluents produced at the plant were reused, reducing water consumption by more than 21 thousand cubic meters per month.