The principal water capture of the group takes place in the cooling systems for the auxiliary services and processes of the thermal generation plants. Most of the water is returned to the environment, partly as evaporated water and the rest included in the discharges from the facilities.
When fresh water is captured for the cooling of thermal plants, a portion evaporates at cooling towers and the remainder is returned to the environment (closed circuit), and when seawater or saltwater is withdrawn, the majority is returned to the sea without significantly changing its state (open circuit). As can be seen in the table below, the majority of water withdrawn is seawater or saltwater.
|2012||GROSS WATER CAPTURE (hm3)(1)||NET WATER CAPTURE (hm3)(2)|
|MARINE ESTUARY, OCEAN||2,882.46||10.41|
|WASTEWATER FROM TREATMENT PLANT||12.33||8.84|
97.4 % of the water collected at thermal generation and cogeneration facilities is subsequently returned to the receptor environment in a physicochemical condition that allows it to be utilized by other users without affecting the natural environment; 0.60% of the water is consumed and/or retained in the different processes and 2% is returned to the environment in the form of steam generated at the cooling systems of the thermal power plants.
In the case of the cogeneration and combined cycle plants of Tarragona Power, part of the water collected is reused in the form of steam, supplying calorific energy equal to 6,734.4 GWh in 2012, which is used for industrial processes or heating systems.
At the Escombreras combined cycle plant, there has been a reduction in the consumption of potable water at the demineralised water treatment plant, reusing industrial effluents. 9.26% of industrial effluents were recovered as compared to the potable water consumed, and there is a 1,144 m3 reduction in potable water. There has also been an improvement in the recirculation of saltwater in the cooling process for the plant’s standby systems, reducing the water captured in the receptor environment by 150 m3.
The reuse of treated wastewater for the cooling systems of some plants in Mexico and the United States is also noteworthy. The latter uses 2.4% water from the network and 97.6% wastewater for all of its processes. In Daldowie Sludge Processing Plant (United Kingdom), the effluent, previously treated and filtered, is recycled for use in its manufacturing processes, saving 100 cubic metres of townswater each day. In the United Kingdom, the Rye House plant can reduce up to 75% of water use through a rainwater collection system which, after being treated, is used as process water. In 2012, the volume of rainwater reused was 30,024 m3.
Half of ScottisPower’s wind farms have rainwater collectors and storage tanks to use the water at the control buildings.
In recent years, no situations have been recorded that significantly affect water resources or the habitats associated with the water-collection points, which are for the most part, significant masses of fresh water or seawater. As can be seen in in the “SOURCES OF WITHDRAWAL” table, 79.1 % of the water captured is seawater or saltwater and does not occur in protected areas.
|USE OF THE WATER (hm3)||CAPTURE||AUXILIARY PROCESS AND SERVICES||EVAPORATION FROM COOLING||DISCHARGE|
|UNITED STATES OF AMERICA||3.22||
|MEXICO AND BRAZIL(4)||55.00||25.44||1.79||28.63|
|GROUP AND AFFILIATES(5)||3,664.42||73.38||21.04||3,570.95|
In Spain and United Kingdom, the discharge volume is the water returned from the cooling systems plus the effluents from the water-treatment plants. These volumes of water are unified in the same trap and returned to the receiving medium. In Latin America, the discharge volume is the cooling water and the water returned from other industrial processes; sanitary water is treated independently. The water used in the cooling process is considered to be the water that evaporates, which is released outside the plant or is marketed as steam in the case of cogeneration plants.
Water use is defined as the water captured, excluding seawater or saltwater and water discharged into the environment; the figures for recent years are:
|Water Use/Global Production (m3)/GWh||699||620||645||715||693||675|
Water use increased in 2012 due to an increase in thermal production (coal and nuclear), which led to higher water needs for cooling, processes, and standby services, particularly if arising from facilities with a closed cooling circuit.
Consumption of water in relation to global production (m3/GWh) has changed the downward trend of recent years due to the increase in coal and nuclear thermal production and the decrease in production with gas combined cycles and hydroelectric plants.
SPECIFIC CONSUMPTION OF COOLING WATER (THERMAL MIX) (m3/GWh)(6)
The specific consumption of cooling water at thermal power plants has decreased due to an increase in the relative weight of nuclear and coal production with open cooling circuits.
EVAPORATED WATER IN THE COOLING SYSTEMS BY TECHNOLOGY (m3/GWh)(7)
|COFRENTES NUCLEAR PLANT||1,632||2,122||2,560|
USE OF WATER IN HYDROELECTRIC GENERATION
The table below shoes net water used in hydroelectric generation, defined as turbined water less pumped water, in Spain and the United Kingdom.
|USE OF WATER IN HYDROELECTRIC GENERATION||2012||2011||2010|
|NET WATER USE (hm3)||42,172||89,515||123,885|
|ANNUAL BALANCE OF RESERVOIR WATER (hm3)||- 1,965||- 2,223||1,442|
|NET HYDROELECTRIC PRODUCTION, SPAIN AND UNITED KINGDOM (GWh)||9,728||18,285||20,025|
Water consumption at offices increased as compared to 2011, mainly in the United Kingdom, due to improvements in the corresponding measurement and management processes., as well as in Brazil upon the inclusion of the subsidiary Elektro. “Rest of world” has decreased with the removal of the Bolivian companies from the scope of the report.
|UNITED STATES OF AMERICA||108,290||86,584||83,563|
|REST OF WORLD||3,111||8,486||9,036|
|GROUP AND AFFILIATES||431,563||367,552||360,869|
The main discharge comes from the cooling systems for the thermal generation plants. The water returned from cooling has insignificant physicochemical changes, including temperature changes. There is a thermal increase based on the difference between the water collected and the water discharged. The government establishes certain maximum allowable values for each plant based on the nature of the collection point and the discharge point (ocean, reservoir or river) and carries out monitoring. The plants continuously monitor the temperature of the discharge, and if limits are exceeded, the facility must correct the temperature or halt production.
Thermal generation power plants in Spain and United Kingdom have water-treatment facilities that treat the waste water before it is returned to the receiving medium (sea, dam or river). Process waters are subjected to a physical and chemical treatment that includes the separation of hydrocarbons. Sanitary water is treated at compact plants with aerobic biological processes. And facilities with coal stockpiles use a runoff treatment, i.e., a settling-coagulation process that prevents particulate or airborne coal from entering the receiving water. Once it has been treated, process and sanitary water is diluted with the water returning from the cooling system, thus ensuring that the returned water has a minimum pollutant load which does not significantly alter the physical and chemical characteristics of the receiving medium.
As regards the treatment of discharges, at the Velilla thermal plant in Spain, biological treatment for desulphurisation commenced in April 2012 at the Effluents Treatment Plant, to reduce nitrides and nitrates in the discharge.
In Latin America, independent separation networks are used for industrial and sanitary water. The latter is subjected to a final treatment in biodigesters, whereas process water goes through hydrocarbon separators before it is returned together with the cooling water to a natural medium or sent to municipal water-treatment plants. In Mexico, the La Laguna plant collects sewage for all its processes, and so the water discharged by this plant has better quality than the collected water as regards certain parameters.
In Spain and México, water is discharged under constant monitoring of various parameters (temperature, turbidity, conductivity, etc.) by the Company and the Administration, to make sure that the characteristics of the effluent are always below the established limits.
As in other nuclear power plants in which the Company holds a stake, the Cofrentes plant carries out thorough controls of direct production process water.
All the effluents of the water-steam cycle, of the reactor coolants and of the ancillary systems are processed by the Liquid Radioactive Waste Treatment System and returned to the cycle for reuse. Exceptionally, owing to maintenance shut-downs, liquids are discharged and mixed with effluents of treated sanitary water and with the effluents of the collected water treatment plant. All the effluents are stored in ponds and are discharged on a regular basis under the control of a representative of the Water Commission.
The Cofrentes nuclear power plant meets the discharge limits imposed by the Hydrographic Confederation of the Júcar. These limits ensure that the conditions established for qualifying the basin's section where the plant's discharge takes place are met and, therefore, the use of the water downstream from the discharge area is guaranteed. Unusually, water collection at this plant takes place downstream from the discharge point. Thus, the plant is the first user located downstream from the discharge area, and the first one to be affected by any potential impact on the river's water quality. The various environmental monitoring programmes (PVRA, hydrobiological programme, etc.) confirm that the plant's discharge activities have entailed no significant impact outside the facilities.
|PARAMETERS||pH||AIRBORNE SOLIDS (t)||DQO (t)||NTOTAL (t)||PTOTAL (t)|
Data for effluents of the water-treatment plants of the combined cycle plants, the thermal power plants in Spain, the Cofrentes nuclear power plant and the EnergyWorks cogeneration plants where we are required to treat the water. Expressed in (t) taking into account the treated effluent ( m3/year) and the concentration ( kg/m3) of each parameter.
|PARAMETERS||pH||AIRBORNE SOLIDS (t)||DQO (t)||NTOTAL (t)||PTOTAL (t)|
|DISCHARGE – COLLECTION||0,1||590,2||192,8||69,8||4,7|
Data for combined cycle and cogeneration plants in Mexico. Taken from analyses conducted on the water discharged to the receiving medium.
Most cogeneration facilities are associated with an industrial process, and the process owner is responsible for water management. For this reason no information is provided on water quality.
In recent years, no situations have been recorded that significantly affect the water resources or the habitats associated with the water-collection and water-discharges points, which are in the majority sizable bodies of fresh or salt water.
Additionally, at the combined cycles of La Laguna and Monterrey in México and at the cogeneration plant of Klamath in the United States, the water collected for cooling comes from municipal wastewater treatment plants, and thus there is no impact.
All water collected is strictly regulated by government administrations, which assign permits and determine the maximum allowed volumes of capture, in order to ensure that no significant impacts occur.
IBERDROLA Group does not have any plants located in areas considered to have water stress. For more information please visit:
Even the discharge from one of the plants has had a positive effect on the receiving medium. This is the case of the Altamira III and IV plant in Mexico. It discharges into the Garrapatas estuary, which had lost its brackish character when its sea water entry was blocked, with the resulting desalination of the ecosystem. Discharge is increasing the level of salinity and the original ecosystem is now recovering.
Several projects are have been performed in Spain by the Company’s Innovation Area to reduce the possible impact on the water medium and its habitat, with significant environmental benefits. We can highlight the project called “Turbines without oil" that will allow elimination of the risk of oil spillages in river water where hydroelectric plants are located and the environmental risks ensuing. These oils are responsible for lubricating mechanical pieces and systems forming part of hydraulic turbines, and it is necessary to insert new mechanical elements not requiring oil for greasing and protection against corrosion. Another important project is the development of a water oxygenation treatment in hydroelectric plants to improve quality in reservoirs. This process avoids an increase in fish mortality due to high levels of hydrogen sulphide in the water.