Responsible use of water resources is one of the strategic targets of the environmental policy and involves the use of an integrated approach based on three lines of action:
Efficient use of water resources also through control of leaks.
The Enel Group withdraws water from water sources mainly for industrial purposes, such as cooling and airborne emissions abatement systems (for example, desulphurization, abatement of nitrogen oxides) and uses it for the most part for thermal and nuclear generation.
In 2018, the total water requirement amounted to approximately 96.3 mil m3, down by around 14.2% compared to 2017 (equal to 112.2 mil m3), due to a lower thermal and nuclear power generation4. The specific water requirement of the Group, including thermal, nuclear, geothermal, and other activities for industrial uses, in 2018 amounted to 0.38 l/kWheq, about 14% lower than the previous year, in line with the target to reduce the Group’s water consumption by 30% in 2020 compared to 2010. The Group’s water consumption calculated according to the new version of GRI Standard 303 “Water and Effluents”5, was equal to 48.7 mil m3 (48,695 ML).
Enel pursues the target of reducing water specific consumption by 30% by 2020, compared to data reported in 2010. The target was based on the results achieved and the timetable laid down by the Business Plan for the next three years, which provides for improvements in water usage efficiency in the existing thermal plants, a shift in the mix towards renewable energies and a reduction in generation from fossil fuels through a change in the composition of the power generation park. Moreover, the Group has set a further target of a 35% reduction in specific water consumption by 2030 vs 2015 based on the better projections now available.
The total water requirements for the Group’s production activities are covered by withdrawing 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. The Group is committed to reducing water consumption in production processes, in particular promoting its recirculation in the plants. In some coal-fired plants, for example, drainage water from the closed-circuit cooling towers is re-used in the desulfurizers, while 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 freshwater withdrawals;
- more efficient management of water, also aimed at maximizing the supply from wastewater and sea water;
- monitoring of sites’ climate and plant data.
In 2018, approximately 8% of total energy produced by the Enel Group used freshwater in “water-stressed” areas6. In these areas water is withdrawn from scarce sources and account for 12% of total usage of the Group. In particular, this category concerns water withdrawn from wells (67% of total Enel usage) and from aqueducts (39% of the total). In 2018, water consumption in “water- stressed” areas was equal to 5.98 mil m3 (equal to 5,978.7 ML), down by 7% compared to the previous year.
The high increase in the number of solar plants, naturally suited to installation in “water-stressed” areas too, has revealed a new use of water, related to cleaning of the photovoltaic panels to remove dust deposited on their surfaces.
Although the volumes involved are not very significant, Enel has adopted cleaning approaches based on algorithms that optimize water consumption.
- Optimization of wastewater treatment and protection of the water quality in the destination environment.
Waste water is water used in plants which, after recovery and re-use for internal purposes, is returned to surface water bodies. Water is always discharged after treatment to removeany pollutants present at a level that does not have negative impacts and in any case is within limits of applicable national regulations.
Where allowed by the local context, Enel has used treated waste water, typically from water management consortia, as incoming water for its own processes. In 2018, the percentage of water sourced from treated waste water totaled 4.7%.
- Responsible management of hydrogeological basins in order to preserve multiple land use and water quality.
An important element in water management is represented by operation of hydroelectric plants.
OPTIMIZATION OF PHOTOVOLTAIC PANEL CLEANING IN CHILE
When operating plants fueled by renewable sources, water is also consumed to clean the photovoltaic panels, to prevent loss of generating power. A specific method that minimizes water used for cleaning, in particular in areas where there is a high degree of water stress, has been perfected in Chile. This method starts from calculation of the level of soiling, assessing the difference in the electrical parameters between the two reference systems (clean panel and dirty panel). By comparing the various available cleaning techniques and the plant operating parameters, amongst other things the model returns the optimized date for the next cleaning operation and a recommended annual cleaning plan.
These plants, which do not contribute to water consumption by the Group since the water they use is totally returned, perform a series of other services for society in addition to simply generating renewable energy.
Several plants are in fact involved in operating their reservoirs, to provide multi-purpose services, managed jointly with the public and private stakeholders concerned, ranging from flood control to potable water and irrigation uses, fire prevention, and management of river waste trapped by the damming works, without forgetting numerous cultural, recreational and naturalistic initiatives organized in relation to the presence of the installations themselves. The contribution of the hydroelectric plant reservoirs is particularly important in the response to the effects of climate changes, since the plants increase the level of protection of the communities that are subjected to ever more frequent extreme flooding events as well as prolonged periods of drought.
Control of reversals from hydroelectric plants through specific programs to guarantee the volumes needed to preserve the ecological status of rivers (minimum vital outflows) must also be underlined.
4 Water requirement figures do not include the water used for open-cycle cooling 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).
5 In 2018, GRI Standard 303 “Water and Effluents” was revised, replacing the previous version dating from 2016. The new standard will come into effect as from January 1, 2021; however, Enel adopted the new version before this date. In particular, GRI 303-5 defines water consumption as the total amount of water withdrawn (defined by Enel as a requirement) minus discharges.
6 The World Resources Institute (WRI) defines a “Water-Stressed Area” as an area where the annual availability of water per capita is less than 1,700 m3.
HANDLING ENVIRONMENTAL EMERGENCY IN NORTH ITALY
During the flooding in October 2018 involving the regions of North-East Italy, besides playing an essential flood control role, Enel’s reservoirs also performed a key function in restraining debris.
Most of the trees felled after the intense rain and high winds and carried by the watercourses were intercepted by the barriers and dams operated by Enel Green Power, preventing the generation of critical situations along the river beds and against bridges and in built-up areas. A considerable quantity of material accumulated in the reservoirs. The most critical situations occurred at the Comelico Dam (15,000 m3 of timber) and Vodo Dam (4,000 m3 of timber). Enel therefore provided resources and funding for removal of the timber from the reservoirs. The recovery operations were conducted by identifying companies that, even in emergency conditions, would guarantee total environmental safety and protection. The destination of the material, not classed as waste following a special resolution of the Regional Council, was defined with the local stakeholders.