USE OF PERCOLATION WATER IN TRACTEBEL ENERGIA HYDROELECTRIC PLANTS REPLACING WATER TREATMENT STATIONS

Transcription

1 USE OF PERCOLATION WATER IN TRACTEBEL ENERGIA HYDROELECTRIC PLANTS REPLACING WATER TREATMENT STATIONS Tractebel Energia S.A. GDF SUEZ 1

2 Contents Introduction 3 Objectives 5 Development 6 Methodology 8 Results 13 2

3 Introduction Machadinho Hydropower Plant: one of the three plants using the water percolation system Leading private company of Brazil s power generation sector, Tractebel Energia S.A. ( is currently operating in 12 Brazilian states with a generating park including 22 power plants comprising hydroelectric, thermo and complementary ones (small hydro power stations, wind farms and biomass plants). By means of these projects, the company generated, in 2010, 42,986 GWh (4,907 MW average), thus corresponding to about 7% of the national market supply. Out of the 22 power plants that make up the generation park of Tractebel Energia, 15 are certified according to standards NBR ISO 9001, NBR ISO 1401 and OHSAS The remaining ones comply with the same management standards, thus leading the company to record operating rates of international reference. 3

4 Tractebel Energia, which is controlled by world sector leader GDF SUEZ, has its main business guideline focused on sustainability, a commitment expressed in Tractebel Energia s Sustainable Management Policy, which was shared with all stakeholders in According to this Policy, the company operates in a manner consistent with the nature of its activity in the management of impacts resulting from its production processes, thus reducing environmental, social and economic risks. Respect for the environment is a fundamental component within the identity and values scope of Tractebel Energia, whose Environment Code provides guidance to its activities. The company has research and development projects and appraises the impacts of its activities while seeking to improve its performance in the prevention and control of pollution, the management of emergency situations, and the sustainable use of renewable and nonrenewable natural resources. Focused on the environmental conservation, Tractebel Energia is constantly seeking to minimize the environmental impact of its activities, giving priority to renewable energy sources and diversifying its power matrix. In addition to the focus on research and development, Tractebel Energia is also investing in the qualification of its employees in order to encourage innovation. In 2010, each collaborator received, on average, 88.6 hours of training and development, thus totalizing an investment of BRL 3.7 million. R&D programs, which have been implemented since 1999, received investments of BRL 12 million only in The concern with the development of its employees, along with an environmental awareness that is part of Tractebel Energia s corporate culture, produces an environment leading to the development of sustainable and innovative solutions. This is confirmed through the use of percolation water which spills from rocky massifs of the water intake in hydroelectric plants for human consumption, a system that was conceived by two employees and that has already been implemented in three hydroelectric plants operated by the company as described below. 4

5 Objectives Percolation water that spills from the rocky massifs of the water intake in hydropower plants General objective Replace Water Treatment Stations responsible for the production of potable water in the facilities of Itá and Machadinho Hydropower Plants with a system that uses water that percolates from the dams. Specific objectives: Preserve natural resources Deactivate the Water Treatment Stations of Itá and Machadinho HPPs Eliminate the production of solid residues resulting from water treatment 5

6 Reduce the use of chemical products in the raw water treatment Reduce power consumption of the process Reduce costs from this process Development Itá Hydroelectric Plant Entrance to the percolation gallery Tractebel Energia encourages its employees to develop innovative ideas and processes. Inove! (Tractebel Energia Program on Innovation Encouragement) is an initiative of the Innovation Committee and receives, appraises, selects and awards 6

7 innovative ideas suggested by employees. In this context, technicians of Tractebel Energia started to look for a solution to replace the conventional system of water supply in the hydropower plants that have a Water Treatment Stations, initially the plants located in the Uruguay River basin, which comprises Itá and Machadinho Hydropower Plants respectively located on the Uruguay River and Pelotas River, on the border between the states of Rio Grande do Sul and Santa Catarina. Later on the solution was replicated to the Salto Osório Hydropower Plant, located between the municipalities of São Jorge D Oeste and Quedas do Iguaçú, in the State of Paraná. In 2003, Itá and Machadinho HPPs were getting ready to receive the ISO Certification, which sets forth the guidelines for the environmental management area in the companies. The Water Treatment Station was, at that time, the procedure found to supply the demand for potable water to be used by employees and visitors in the management and operation areas of the plants. The projects, which were isolated from urban centers and water supply companies, had to implement their own treatment stations using water from the reservoirs. The Water Treatment Stations, with high implementation and operation costs, required the use of chemical products to remove solid agents and other impurities from raw water, and required the proper elimination of solid residues. Furthermore, it was necessary to use a contractor to operate the Stations while there was a constant demand for maintenance because the equipment would deteriorate rapidly due to the intensive use of chemical products such as caustic soda. The first alternative to be analyzed by Tractebel Energia was the construction of an artesian well for catchment of water. At that time and during periodical inspections of installations, the technicians of Tractebel Energia started observing the water behavior in percolation galleries, which until then had no use at all. These galleries are excavated during plant construction in the rocky massif that surrounds the engine room and are used to alleviate the flow and drain water from the reservoir that infiltrates in the rock. During a superficial analysis, the technicians noticed that the water that spilled inside the gallery of plants was clear and abundant. However, some tests and confirmations still needed to be performed so that the new system would be implemented. 7

8 Methodology In 2006, the technicians suggested the deactivation of the Water Treatment Stations of both power plants and their replacement with the use of water from percolation galleries. The idea was submitted to the managements of both Plants, who performed according to the company s environmental management guidelines to carry out the planning. All Tractebel Energia power plants have authorizations and environmental licenses issued by the environmental agencies since the feasibility study phase until the implementation and operation of the projects. In addition to legal obligations, the company implemented a management system that, among other functions, guides its collaborators in the proposition of new ideas and processes. The Integrated Management System of Quality, Environment, Health and Safety in the Workplace (SIG) covers procedures, tools and environmental programs to control risks and identify opportunities aiming at operation improvements of both processes and services. Currently, SIG is certified according to the requirements of NBR ISO , NBR ISO and OHSAS in 15 out of 22 power plants operated by Tractebel Energia including the three where the solution was implemented. The System is the guide of Environmental Management Programs, which set forth a methodology to be followed in order to plan medium and long term activities. In the case of replacement of Water Treatment Stations with the new system, in 2007, Environmental Management Programs were issued. These Programs helped in the planning to confirm the feasibility of water use for human consumption and compliance with ISO Certification. The two main factors that needed to be verified to prove the efficiency of the new system were water the quality and the flow. The confirmation that the water was adequate for consumption came after lab analyses and quality monitoring. The natural filter of rocks and little chlorination assure the potability of percolation water. Initially, for chlorination of water caught, a dripping process was used. However, the process was not accurate and required constant human intervention in the supply. As a result, suppliers were contacted to provide a chlorination system using inserts that provides precision to the treatment and reduces human intervention. After the project implementation, water quality continued to be quarterly monitored in accordance to the legislation in force. 8

9 The second step, which was also decisive for the continuation of the project, was the checking of the flow in the galleries, which should be enough to meet the consumption of the power plants. By using reports of a contractor responsible for auscultation services of both plants, it was possible to record the historical flow of galleries since the filling of reservoirs. Based on this record, the capacity of galleries to supply the plants with potable water was calculated. Internal view of gallery with water percolating In order to avoid doubts on the efficiency of the new solution, in addition to historical averages, a 12-month water volume monitoring was carried out. In this period of time, the Water Treatment Station was capable to operate simultaneously with the new system as a redundancy measure for security. The complete weather cycle tested the system: the region suffered a rigorous drought between December 2007 and March 2008 and even in these conditions the flow proved to be sufficient and constant to meet the needs. In this same cycle, it was also verified that even in intense rainy seasons the percolation water remained clear contrary to the turbidity shown in the reservoir water. 9

10 A decision was made to develop alternatives for catchment and conduction of the water to relevant reservoirs. The water spilling from the galleries is concentrated in ducts that fall into a catchment basin. The basin has two exits one that leads to the well, with a valve, and another one being used as overflow, in which exceeding water is eliminated. The Machadinho HPP did not require the use of electric energy to pump water from galleries to the well because the slope allowed the use of gravity force to conduct water to the reservoir. At the Itá HPP, a pumping is performed to a water tank, which then supplies consumption points of the power plant. Upon the success of the solution, its main goal was achieved in 2009 when the Water Treatment Stations had their operations interrupted in both plants. In view of the natural quality of percolation water and the simplicity of the system, its implementation cost was only BRL 17 thousand for both Itá and Machadinho Hydropower Plants. By way of comparison, this value corresponds to three months of operation of each Water Treatment Station in said plants. Since it was implemented in the Itá and Machadinho HPPs, the system did not have any problems. The only interventions made are the resupply of sodium hypochlorite inserts and regular cleaning of both galleries and reservoirs. After the consolidation of the pioneering implementations, a work instruction was made to operate the new potable water supply system in the Uruguay River plants. Replication Following the success achieved in the Itá and Machadinho Hydropower Plants, a decision was made to appraise the implementation feasibility of the solution in other plants operated by Tractebel Energia and that could also deactivate Water Treatment Stations. Historical data analysis of percolation flow measurements and water potability were carried out at the Salto Osório Hydropower Plant, located in Paraná, and under operation since Similarly to the other two plants, Salto Osório also issued an Environmental Management Program, which helped in the planning and implementation of the water percolation system in the plant. The new system carried out the efficiency tests phase between September and December In this period of time, the Water Treatment Station remained capable of operating to make up for an occasional failure of the new system, something that did not happen. The effective start-up of the new system and deactivation of the Station happened in January The system developed for the Salto Osório HPP 10

11 abided by the principles applied to the Itá and Machadinho plants taking into account that some adaptations were required to meet specific topology features of the plant such as the distance between galleries and the difference of level with regard to the covering of the control building, where the water tank used to meet the plant consumption is located. At the Salto Osório HPP, the implementation cost was BRL 131 thousand. In spite of the difference in implementation costs, operation and maintenance costs as well as the benefits in the environmental impact reduction have justified the accomplishment of the project. Chlorination in the catchment basin and clear water in the catchment basin Information graphics detailing the catchment operation as well as the treatment and distribution of percolation water at the Salto Osório, Itá and Machadinho Hydropower Plants are shown below. 11

12 New Water Supply System of Salto Osório HPP Water intake gallery Water tank l m 3 Chlorination and Water tank l m 4 5 Transformers floor Control building Powerhouse Tunnel under spillway 1 and dam access Tunnel under penstocks m Pumping station 2 Percolation water of rocky massif: 500 liters/hour 1 1 Source 2 Storage / discharge 3 Storage / distribution 4 Treatment with chlorine 5 Treated water storage 12

13 New Water Supply System of Itá and Machadinho HPPs Innovation: Use of percolation water of Tractebel Energia hydroelectric plants replacing Water Treatment Stations (ETA s) 1 The system uses the reservoir water that naturally infiltrates in the rocky massif upstream the Engine Room and drained to the percolation galleries. Rocky massif Engine room 4 The system allows the deactivation of the water treatment station. Water tanks Managing quarters Percolation gallery Relief drains 2 After crossing the rocky massif, the water spills crystal clear in the percolation gallery simply requiring chlorination. Water 3 The water is channeled and goes to water tanks of both managing quarters and engine room. At the Itá HPP, the water is pumped and at Machadinho HPP it flows by gravity force. Innovation benefits PRESERVATION of natural resources Drinking WATER for both plants, not requiring human control LOW implementation cost: R$17 thousand for each plant, corresponding to three operation months in each ETA DEACTIVATION of ETA s in 2009 Total cost reduction of R$3,7 MILLIONduring the concession period ELIMINATIONof chemical products for water treatment END of solid residues by means of mud elimination from ETA s REPLICABLE in power plants operated by Tractebel Energia IMAGE gains with stakeholders Results Environmental gains Elimination of chemical products consumption for water treatment since substances such as aluminum sulphate and caustic soda are no longer used The system prevents the production of solid residues with the elimination of mud coming from the Water Treatment Station, which had high iron, aluminum, manganese and organic matter content Eliminates the need for transporting these residues to landfill areas that in the case of Itá HPP were located 75 km away, and in Machadinho HPP 180 km away 13

14 Social gains Supply of quality drinking water to employees and visitors of plants, with no chemical product, except for small chlorination (in order to avoid the development of algae and pathogenic microorganisms The community under the influence area of plants started to have preserved hydric resources downstream the reservoirs without contamination risks coming from the Water Treatment Stations operation Social dissemination of knowledge by means of visiting programs to the plants, in which people from the community, representatives of governmental agencies and NGOs will learn about the innovative solution, in addition to its presentation in technical congresses of the power sector Economic gains Low operation and maintenance cost in the three HPPs. Also to be highlighted the low implementation cost in Itá and Machadinho Power HPPs, BRL 17 thousand a value corresponding to three months of operation of each Water Treatment Station Deactivation of the Water Treatment Stations of Itá and Machadinho HPPs in 2009 and Salto Osório in January 2011, thus allowing the cancelation of operation contracts of Itá and Machadinho HPPs As for Salto Osório HPP, a reduction in operation and maintenance costs is estimated at the amount of BRL 38 thousand a year. Taking into account the 19 years of concession, the saving is expected to be BRL 722 thousand Costs elimination that totalize BRL 3.7 million in Itá and Machadinho alone, taking into account their concession terms according to the following spreadsheet: Costs avoided with the implementation of the new system at the Itá and Machadinho Hydropower Plants COSTS AVOIDED Itá HPP Costs Value BRL/year Value/22 years of concession Operation contract 72,708 1,599,576 Maintenance cost (human and material) 6, ,402 Residues destination cost 2,500 55,000 Total avoided cost 81,999 1,803,978 14

15 Machadinho HPP Costs Value BRL/year Value/22 years of concession Operation contract 72,708 1,744,992 Maintenance cost (human and material) 2,626 63,024 Residues destination cost 2,500 60,000 Total avoided cost 77,834 1,868,016 Itá and Machadinho HPPs Total avoided cost 159,833 per year 3,671,994 for the concession term Tractebel Energia has implemented in three of its hydropower plants an innovative solution developed by technicians of the company, which replaces Water Treatment Stations. The use of percolation water which spills from the rocky massifs of the water intake of plants for human consumption in the project has proved to be a simple, efficient alternative whose cost is lower than the traditional system and with little environmental impact. 15