The integrated management of water resources is based on the following main lines of action:
- efficient use of water resources also through losses control;
- optimization of wastewater treatment and protection of the water quality of the destination environment;
- management of releases from hydroelectric plants through specific programs to guarantee the volumes needed to preserve the ecological status of rivers (minimum vital outflows);
- integrated management of hydrogeological basins in order to preserve multiple land use and water quality.
The Enel Group takes water and uses it for the most part for thermal and nuclear production mainly for industrial purposes, such as cooling and atmospheric emissions abatement systems (desulphurization, abatement of nitrogen oxides).
In 2017 the total water requirement amounted to about 126 Mm3, with a reduction of around 15% compared to 2016 (149 Mm3). The decrease in water consumption is mainly due to the exit from the perimeter of two Slovakian nuclear power plants, which has led to a 61% reduction in the specific water needs for nuclear production in the last three years, from 2015 to 2017. The specific water needs of the Group, including thermal, nuclear, geothermal, and other activities for industrial uses, in 2017 amounted to 0.49 l/kWheq, about 11% lower than the previous year, in line with the target to reduce the Group’s water consumption by 30% in 2020 compared to 2010.
Specific water consumption for the production cycle (I/kWheq)
In 2017 about 8% of the total production of the Group used and/or consumed fresh water in water stressed areas (defined as areas in which the annual water per capita availability rate is less than 1,700 m3).
The total water requirements for the Group’s production activities are covered by usage from sources that are not scarce (sea water), scarce (surface soft water, groundwater and from industrial aqueducts), or through the use of wastewater from production processes.
In 2017, usage from scarce sources amounted to approximately 111 Mm3, a decrease of about 17% compared to 2016, also due to the exit from the perimeter of the Slovakian asset – in particular the nuclear power plants, which mainly use river water. Consumption figures do not take into consideration the water used in open cycle because it is returned to the original body of water in the same quantity, with unchanged chemical characteristics and minimal temperature variations (always within the limits set by the regulations in the countries where Enel operates). In total, 99% of the water used for open cycle cooling in Enel plants is returned to the original bodies of water.
Enel is committed to reducing water consumption in production processes, in particular by encouraging the application of multiple water usage systems as much as possible. In some coal-fired plants, for example, the use of crystallizers downstream of the desulfurizers allows the total recovery of the wastewater.
Enel constantly monitors all production sites in areas at risk of water scarcity in order to manage the water resource in the most efficient way. In particular, site monitoring takes place through the following levels of analysis:
- mapping production sites in areas with potential “water scarcity” situations, in which the average value of renewable water resources per person is lower than the reference set by FAO (the mapping is carried out with the Global Water Tool of the World Business Council for Sustainable Development);
- identification of “critical” production sites, i.e. those in “Water Scarcity Areas” with withdrawals;
- more efficient management of water, also aimed at maximizing the supply from wastewater and sea water;
- monitoring of sites’ climate and vegetation data.
As regards hydroelectric plants, in addition to complying with the requirements of the different territorial Protection Plans that impose the obligation to release the minimum vital outflows, Enel has simultaneously launched experiments in Italy, Spain and Latin America concerning the real impact on the ecosystem of these outflows. In some specific cases, it has also launched studies aimed at examining the effect of the daily flow variations caused by the intermittent releases of turbinated waters downstream of the plants.
Research and innovation in the conservation of water resources
Enel’s Global Thermal Generation, in collaboration with Global Renewables, coordinates the European MATCHING project (Materials & Technologies for Performance Improvement of Cooling Systems in Power Plants), funded under the Horizon 2020 program. The consortium, which brings together 16 partners between utilities, research bodies and vendors, aims to develop new technologies to reduce the use of water for cooling in thermal production and to optimize its use in geothermal power plants. Launched in 2016, the first phase of the project focused on the development of pilot projects in the laboratory. The first phase, which has had positive results, was followed by the experimentation phase in seven major European plants, including the thermal plant of As Pontes, in Spain, the thermal plant in Brindisi and the geothermal plant in Nuova San Martino, in the district of Lago, both in Italy.
In terms of water recovery, in the Italian geothermal sites Enel Green Power has been using “Closed Loop” treatment for several years, which allows the separation of bentonite (the fluid used for drilling operations, also known as sludge) from the water itself. This process makes it possible both to reduce water consumption, reducing the transfer of solid waste to landfills, and recovering reusable water to prepare new sludge, to dilute the circulating water and to wash the equipment. With regard to thermal plants, moreover, the innovative “Zero Liquid Discharge” process was implemented in some Italian plants, with the aim of making the use of water perfectly efficient. Through this process, all wastewater is reused in the production cycle, eliminating effluent and reducing consumption.
Enel has committed to achieving a 30% reduction of specific water consumption by 2020 (compared to the data recorded in 2010). The target was set in view of the results achieved and the timetable laid down by the Business Plan for the next three years, which will see improvements in the efficiency of water usage in the existing thermal plants, an evolution of the mix towards renewable energies and a reduction in generation from fossil fuels through a change in the perimeter of the production fleet.
Wastewater includes water for industrial use and rainwater collected from the internal areas of production sites, potentially polluted by oils, which after a treatment process are returned to surface water bodies, or reused.
Enel pays close attention to the quality of its discharges to surface waters and invests to improve its effluent treatment plants. Potentially polluted waters produced at the sites are sent to specific treatment plants depending on the type of substances that may be present. The treated wastewater – amounting to about 108 Mm3 in 2017 (about 112 Mm3 in 2016) – are partly returned to surface water bodies and partly reused within the plants themselves, helping to meet total water needs. The percentage of reuse varies depending on the technical characteristics of the plants and the use of crystallizers in some coal plants.
In 2017, the amount of wastewater recovered after treatment across the Group amounted to around 7 Mm3, meeting 5.4% of total needs. This increase compared to 2016 (+30%) is mainly due to the removal of the Slovakian power plants from the consolidation.