The integrated management of water resources is based on the following guidelines:
- efficient use of water resources and protection of water quality in production processes;
- treatment of effluents and their minimization also through control of losses;
- management of releases from hydroelectric power plants through specific programs to guarantee the volumes necessary to preserve the ecological state of rivers (minimum flows);
- integrated management of water basins to preserve the multiple uses of the local area and the water quality.
Volumes of water used per production process (m. m3)
The Enel Group draws off water mainly for industrial purposes, such as cooling, desulfurization, reducing nitrogen oxides, etc. and uses it mainly in thermoelectric production and nuclear energy production.
In 2015 the total quantity of water drawn off was around 175 million m3, a 6% reduction compared to 2014 (186 Mm3), mainly thanks to the coming into operation of the new dry ash removal system at the Reftinskaya power plant.
Volumes of water drawn off by source (%)
Specific consumption in 2015 totaled 0.60 l/kWh, enabling Enel to reach the 10% reduction target to 2020 compared to the figure for 2010 five years in advance.
Specific net consumption of industrial water in overall production of electricity and heat (l/kWh)
Compared to the figures recorded in 2010, Enel has set a new reduction target of 30% in specific water consumption by 2020 (previous target -10%).
In addition, in 2015 only 6% of the Group’s total production used and/or consumed freshwater in water-stressed areas. Total water requirements are covered through the use of water drawn from so-called “scarce” sources (surface and underground water and from aqueducts) or by using “nonscarce” sources, such as seawater and effluents arising from the Group’s production processes.
In 2015 the draw offs from scarce sources totaled around 158 million m3, down compared to 2014 by 6%, mainly from rivers and rainwater (92%). The percentage of use of effluents from production processes rose slightly to stand at 3.9% of total draw offs in 2015.
Other requirements, such as open-cycle cooling, are covered without any real consumption, using sea or fresh water which is drawn and then returned to the original body of water in the same quantity, with its chemical properties unchanged and with minimal changes in terms of temperature (always within the limits set by the laws in the countries where Enel operates).
99% of the water used in Enel power plants is returned. This percentage corresponds to the water used in open cycles where the water is used only for cooling.
The cover of the water requirement for industrial use shows, in percentage terms, the contribution of the various water sources (fresh water, seawater, effluents). The total contribution from fresh water (rivers, wells, and aqueducts) remained stable compared to 2014.
Cover of water requirement for industrial use (%)
Enel is engaged in reducing water use in production processes, in particular by favoring as far as possible multiple use systems for water. For example, in coal-powered plants, the drainage water of closed-circuit cooling towers is reused in desulfurization systems, while the installation of crystallizers downstream from desulfurization systems enables the total recycling of effluents.
The focal points of Enel’s management of water resources are: measuring performance (for example, specific consumption, polluting load of effluents), definition of policies and specific targets (public objective to 2020 on specific water consumption at Group level), analyses and studies on European and international legislation to set out possible future scenarios.
The assessment of water risk
Enel constantly monitors all the production sites in areas at risk of water shortage in order to manage this resource more efficiently. In particular the monitoring of sites involves the following levels of analysis:
- mapping of production sites in potential water scarcity areas, in which the average value of renewable water resources per head is lower than the reference value set by the FAO(12);
- identification of “critical” production sites, i.e. which use fresh water;
- more efficient management through changes to plants or processes aimed at maximizing the supply from effluents and sea water;
- monitoring of the climate and vegetation data for each site.
Besides compliance with the various regional Safeguarding Plans (for plants located in Europe), which impose an obligation to release minimum flows, Enel has in parallel launched in Italy, Spain and Latin America tests regarding the real impact on the ecosystem of such flows and, in some specific cases, studies aimed at analyzing the changes in daily flow caused by the intermittent introduction of turbinated water downstream from power plants.
Effluents include the residues of water for industrial use and rainwater collected by the internal areas of thermoelectric power plants, and they are potentially polluted by oil.
Enel pays close attention to the quality of its discharges into water, and constantly invests to improve the features of effluent treatment plants which have lower standards.
In all the Group’s sites where polluted water is produced there are specific treatment systems depending on the type of pollution present. The effluents thus treated are partly discharged into surface water and partly reused in the plant itself, thus helping to cover total water needs.
In 2015 the recycling of effluents after treatment, across the Group, was around 7 million m3, which enabled coverage of 3.9% of total consumption, or 175 million m3.
(12) This mapping is done using the Global Water Tool of the World Business Council for Sustainable Development.