Denawaka Ganga Mini Hydro Power Project

Last updated
Denawaka Ganga Mini Hydro Power Project
Denawaka Ganga Mini Hydro Power Project power house.jpg
Power House
Country Sri Lanka
Location Ratnapura, Sabaragamuwa Province
Coordinates 06°42′12″N80°26′59″E / 6.70333°N 80.44972°E / 6.70333; 80.44972
Purpose Power
StatusOperational
Construction beganOctober 2009 (2009-10)
Opening dateFebruary 2012 (2012-02)
Owner(s)Country Energy (Pvt) Ltd, a subsidiary of Vallibel Power Erathna
Power Station
Type run of the river
Installed capacity 7.2 MW
Annual generation 25 GWh

Denawaka Ganga Mini Hydro Power [1] [2] Project is a run of river mini hydro power project located in Ratnapura, Sri Lanka. The install capacity of the project is 7.2 MW and the annual generation is 25GWh. The generated energy is fed into the national electric grid of Sri Lanka.

Contents

Introduction

The plant uses the water flow of the river "Denawaka Ganga", which is the main tributary of the river "Kalu Ganga". Denawaka Ganga is formed by the confluence of river "Denawaka Ganga" (Upper) and river "Bambarabatu Oya" at a location known as Mawella. The headwaters of both rivers originate in the Bambarabatuwa forest reserve, a wet zone forest extending over more than 5,000 Hectares. Both rivers flow in a westerly direction south of the Adams Peak hill range, on the southwestern slopes of Sri Lanka. The catchment basin of the source, especially the Bambarabatu Oya sub-catchment, experiences some of the highest and most consistent rainfall in Sri Lanka. In total, the plant has a catchment area of 172.58km2.

The project comprises a diversion weir, intake, headrace channel, forebay, penstocks, powerhouse, tailrace, and switchyard. The intake structure is on the right bank of the river and the waterway continues for 1,800 meters in a channel with a box section up to the forebay tank. Then, water is taken through penstocks for a distance of 107 meters to the powerhouse.

Since the project is a run-of-the-river type, no need of storing water is required at the weir. The water leaves the generating station and is returned to the river without altering the existing flow or water levels. The electricity is stepped up to 33kV to match the transmission voltage of the local grid. The generated power is then transmitted through a 33kV line to the grid substation.

In the hydropower generation process, there are no greenhouse gas emissions and it does not involve the burning of fossil fuels during the process. Thus, electricity is generated through sustainable means without causing any negative impact on the environment. Hence, the technology adopted for the project activity is an environmentally safe and sound technology.

Location of the Power Plant Power Plant Location.png
Location of the Power Plant

Location

The Project area is located near Durekkanda, 9 km from Rathnapura Town in the Rathnapura Divisional Secretariat of the Rathnapura District in Sabaragamuwa Province of Sri Lanka.

Topography surveys of the project area are available in sheet 75 – Balangoda which on a scale of 1:50,000 by the Survey Department of Sri Lanka. The Geo Coordinates of the project activity are as follows, Weir - 060 41’ 39” N & 800 28’ 06” E Power Plant - 060 42’ 12” N & 800 26’ 59” E

The project location is close to the town of Ratnapura approximately 115 km from Colombo and the project is accessible from the main Ratnapura-Balangoda road. The site is reached by turning right just beyond the Malwala town and proceeding approximately 3 km on a by-road

General Arrangement of Project Construction Area around Forebay and Power House Denawaka Ganga Sketch structure 1-Model.jpg
General Arrangement of Project Construction Area around Forebay and Power House

Project Implementation

The project developer is Country Energy (Pvt) Ltd, a subsidiary of Vallibel Power Erathna PLC, [2] which is one of the leading mini hydropower developers in Sri Lanka. [3]

The development of the project was initiated in September 2002 with the investigation of the feasibility of the project and it was decided to develop the project with a capacity of 4.9MW. It took a few years to go through various regulatory clearances from the government authorities and a portion of government land was released in the year 2008 after a long process. Vallibel Power Erathna PLC acquired the project in early 2009 and decided to increase the capacity up to 7.2MW after a fresh feasibility study by the Vallibel project team [4] then, the construction works were started in October 2009 [1]

The project commenced with construction work on an access road. Parallel to that, bungalow, batching plant, crusher, bulk material store yards, stores, working yards, site office and labour camps were properly structured and everything was managed in a good professional manner. This made the work more efficient and effective.

Weir

The weir of 30 m in length with a maximum height of 2.5 m was constructed to divert water to the intake. The weir is a straight concrete gravity structure made of plum concrete with an ogee profile. In order to prevent silt and trash from entering the channel, a trash screen was utilized. [2]

Intake

Inspection of Weir Location by Chairman of the Vallibel Group, Dhammika Perera (R) & Chief Executive Officer, Aruna Dheerasinghe (L) Inspection of Weir Location.jpg
Inspection of Weir Location by Chairman of the Vallibel Group, Dhammika Perera (R) & Chief Executive Officer, Aruna Dheerasinghe (L)

Intake was constructed with 4 sluice gates of 3m in width and 2.5 m in height. It satisfies the requirement of getting 25m3/s flow with 1.25 m/s intake flow velocity. The intake conveys the water into the concrete headrace channel. The intake is 30m long, 20m wide and 2.2m deep. [1]

Headrace Channel

Inspection of Channel Path by chief executive officer; Aruna Dheerasinghe and the Site Manager; Mr Balasooriya Inspection of Channel Path.jpg
Inspection of Channel Path by chief executive officer; Aruna Dheerasinghe and the Site Manager; Mr Balasooriya

The intake leads to the rectangular profiled headrace channel of 1,800 m length which was made of reinforced concrete. The headrace channel lies on the right bank of the stream and it has 4.4m inner width and 2.2m of wall height while the design flow is 27m3/s. This bank has moderately steep slopes, and the bedrock is marginally weathered. Reinforced concrete channel sections were placed on screed concrete and expansion joints were provided at every 17m with 250mm wide rubber water bars. [2]

Forebay

The headrace channel ends at the forebay tank. The forebay was made of reinforced concrete with a trash screen of 8.5m x 5.5m and it was placed before the penstock entry. The top of the forebay was covered while a spillway is constructed just upstream of the forebay. The forebay tank is 50m long and 9.3m wide. The maximum height of the tank is 10m. [1]

Penstock

After the forebay, water diverts into the penstock to deliver water into the turbines. The penstock comprises three welded steel pipes at the forebay, having a diameter of 1850mm each. Then the three pipes reduce to 1785mm diameter at Anchor 2. At the third anchor, the middle pipe bifurcates into two pipes having diameters of 1220mm each and the other two reduce to 1720mm in diameter and continue the same up to the powerhouse. The penstock trace is geologically well stable, and minor excavation was required to construct the penstock.

The pipe was spiral welded steel made to American Petroleum Institute standards (API 5L Grade B). The pipe was brought to the site in 5.8m sections and welded together at the site. The total length of the steel pipes was covered with reinforced concrete and it was buried with soil. The length of the penstock is 107m and the design flow of one pipe is 8.3m3/s for each of the 3 pipes. [1]

Powerhouse

Power House Denawaka Ganga Mini Hydro Power Project, Power House.jpg
Power House

The powerhouse consists of the turbines, generators and control room. The turbine bay contains a 25MT capacity crane for handling of the equipment during installation and repairs. The necessary transformer and high voltage switchgear were housed outside the powerhouse.

The project generates electricity at 6.6kV and then steps it up to 33kV via four transformers. The electricity generated is exported via a 33kV transmission line of 10.2 km length to the 33kV line at the Ratnapura Grid Substation.

The powerhouse was built adjacent to the river at the downstream end of the drop. It is 54m long, 14.5m wide and 18m high.

Electro-mechanical Equipment

Turbines and Generators Turbines and Generators.jpg
Turbines and Generators
Control Panels Denawaka Ganga Mini Hydro Power Project, control panels.jpg
Control Panels
Transformers Denawaka Ganga Mini Hydro Power Project, Transformers.jpg
Transformers

The power generation units are manufactured by Dong Feng Electric Machinery Works Co., Ltd (China) [2] and have a total capacity of 7.2 MW. More details on the applied technology are as follows,

Turbine 1 & 2
Model : HLA551C-WJ-112
No. of Units : 2
Mean Diameter of Runner : 1.12 m
Rated Speed : 428.6 rpm
Max runaway speed : 890 rpm
Type : Horizontal Francis hydro turbine
Turbine Power Output : 2,660 kW
Turbine 3 & 4
Model : HLA551C-WJ-80
No. of Units : 2
Mean Diameter of Runner : 0.8 m
Rated Speed : 600 rpm
Max runaway speed : 1,246 rpm
Type : Horizontal Francis hydro turbine
Turbine Power Output : 1,246 rpm
Generator 1 & 2
Model : SFW2500-14/2150
No. of Units : 2
Rated output power : 2,500 kW
Rated voltage : 6,600 V
Excitation : Static SCR excitation
Rated Speed : 428.6 rpm
Max runaway speed : 890 rpm
Generator 3 & 4
Model : SFW1250-10/1730
No. of Units : 2
Rated output power : 1,250 kW
Rated voltage : 6,600 V
Excitation : Static SCR excitation
Rated Speed : 600 rpm
Max runaway speed : 1,246 rpm

Tailrace

The tailrace channel conveys the tailwater back to the river.

Transmission Line

The 33kV transmission line was 10.2 km long, and connected up to the 33kV line at the Ratnapura Grid Substation. A single circuit concrete pole line was built along the road from the powerhouse to the feeder.

Financial Background

Total investment of the company was 905 MN LKR and Equity to debt ratio is 30:70. Debt facilities were arranged by Commercial Bank, Hatton National Bank & DFCC Bank. [5] [6]

Design

Project Team of Vallibel, Aruna Dheerasinghe and Sampath Abeysinghe Team of Denawaka Ganga Mini Hydro Power Project.png
Project Team of Vallibel, Aruna Dheerasinghe and Sampath Abeysinghe

Power House Structural design was carried out by Stems Consultants (Pte) Ltd, while its architectural design concept was from the Vallibel team. The structural designer of the weir, intake, channel and forebay was D.F.M. Perera. The hydraulic designs for the weir, intake, channel, forebay and penstock were done by G.G. Jayawardhana, and Aruna Dheerasinghe and powerhouse hydraulic designers were Dong Feng Electric Machinery Works Co., Ltd The plant is commissioned in February 2012 and since then it serves Sri Lankan national grid by providing 25GWh of green energy in every year. [7]

Contribution to Sustainable Development

Environment benefits

The renewable electricity generated by the project displaces electricity produced by fossil fuel power plants leading to lower overall emissions of SOx and NOx from the grid as a whole. In the hydropower generation process, there are no greenhouse gas emissions and it does not involve the burning of fossil fuels during the process. Thus, electricity is generated through sustainable means without causing any negative impact on the environment. The project reduces approximately 13,500 tCO2e of annually as a result of displacement of fossil-fuel based grid electricity in Sri Lanka. [1] [8]

The company is always concerned about the greenery management of the site and many environmental management programs are run to fulfil the requirement.

Social Development

The project activity created a lot of social benefits. It increased employment opportunities and the income of local people during the construction period. During the operation and construction period, the project created new training opportunities for the local community members. In addition, the local community benefited from new access roads, donations to the local schools, and the provision of medicines for children. In addition, the general public at large including the local residents and communities indirectly benefited from the greater availability of clean electricity in the national grid which would otherwise be met through grid-connected fossil fuel-based power plants. [2]

Social Welfare

This project worked closely with the community to upgrade their standard of living and made a genuine contribution to their lives. During the construction of the plant, the welfare of the community, minimal disturbance to lifestyles, and construction and maintenance of the roads are prioritized. The welfare activities are as follows. [9] [10]

Environmental Impacts

This project results in a reduction in the water flow between the weir and the powerhouse and mandatory discharges are released throughout the project life to avoid any impact on the river ecosystem. The water quality does not change due to the implementation of the project and there is no change in the water availability downstream too. The potential environmental impacts identified were soil erosion, loss of soil stability and slope failure, reduction in the river flow between the weir and tailrace, and some ecological impacts such as interference with fish mobility, destruction of plants and noise. But, the potential impacts in this project were negligible comparatively and all the precautions were taken to minimize the impacts as per the recommendations of relevant authorities and consultants. [8] [4] [7]

Awards and Certificates

Confirming that the Denawaka Ganga MHP is an environmental friendly project, UNFCCC (United Nations Framework Convention on Climate Change) registered it as a Clean Development Mechanism (CDM) project [11] CDM project consultant was Mitsubishi UFJ Morgan Stanley Securities Co., Ltd and coordination work from Country Energy (Pvt) Ltd was done by chief executive officer; Aruna Dheerasinghe and Engineer; Tharanga Baduge. The validator of the project was TÜV NORD CERT GmbH.

Related Research Articles

<span class="mw-page-title-main">Micro hydro</span> Hydroelectric power generation of 5 to 100 kW of electricity

Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks, particularly where net metering is offered. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel. Micro hydro systems complement solar PV power systems because in many areas water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum. Micro hydro is frequently accomplished with a pelton wheel for high head, low flow water supply. The installation is often just a small dammed pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing. In low head sites, generally water wheels and Archimedes' screws are used.

<span class="mw-page-title-main">Tenom Pangi Dam</span> Dam in Tenom, Sabah, Malaysia

Tenom Pangi Dam is a hydroelectric plant in Tenom, Sabah, Malaysia. It is located 120 km (75 mi) south of Kota Kinabalu on the Padas River. The project is a run-of-river hydroelectric power plant. Tenom Pangi Dam is the only major hydroelectric dam in Sabah.

<span class="mw-page-title-main">Ambuklao Dam</span> Dam in Benguet, Philippines

Ambuklao Dam is part of a hydroelectric facility in Baragay Ambuclao, Bokod, Benguet province in the Philippines. With a maximum water storage capacity of 327,170,000 cubic metres (265,240 acre⋅ft), the facility, which is located 36 km (22 mi) from Baguio city, can produce up to 105 megawatts of electricity for the Luzon grid. The main source of water is the Agno River, which originates from Mount Data. The dam is located in a conservation area known as the Upper Agno River Basin Resource Reserve.

<span class="mw-page-title-main">Koyna Hydroelectric Project</span> Power plant in India

The Koyna Hydroelectric Project is the second largest hydroelectric power plant in India, just after the Tehri Dam Project. It is a complex project with four dams including the largest dam on the Koyna River, Maharashtra, hence the name Koyna Hydroelectric Project. The project site is in Satara district.

<span class="mw-page-title-main">Stave Falls Dam and Powerhouse</span> Dam in Stave Falls

Stave Falls Dam is a dual-dam power complex on the Stave River in Stave Falls, British Columbia, Canada. The dam was completed in 1912 for the primary purpose of hydroelectric power production. To increase the capacity of Stave Lake, the dam was raised in 1925 and the Blind Slough Dam constructed in an adjacent watercourse 500 m (1,600 ft) to the north, which was the site of the eponymous Stave Falls. In 2000, the dam's powerhouse was replaced after a four-year upgrade. The original Stave Falls powerhouse was once British Columbia's largest hydroelectric power source, and is a National Historic Site of Canada.

Golen Gol Hydropower Plant (GGHPP) is a hydroelectric power plant located on the Golen Gol River - a major left tributary of Mastuj River in Chitral District of Khyber Pakhtunkhwa province of Pakistan. The dam is located approximately 25 km from Chitral city, and 365 km from the provincial capital of Peshawar. Construction of Golen Gol project began in 2011, and was completed in January 2018.

Gulpur Hydropower Plant (GHPP) is an operational run-of-the-river hydroelectric generation project located on Poonch River, a major tributary of Jhelum River near Gulpur in Kotli District of Azad Kashmir, Pakistan. The site is about 167 km from Federal Capital Islamabad and 285 kilometres (177 mi) from Punjab's Provincial Capital Lahore and is approachable directly from Islamabad and Lahore by a two-lane, all-weather, paved, partly mountainous road. The location of the project is about 28 km upstream of Mangla Dam Reservoir.

<span class="mw-page-title-main">Snoqualmie Falls Hydroelectric Plant</span>

The Snoqualmie Falls Hydroelectric Plant is located just north of Snoqualmie in King County, Washington state, US. It is situated about 22 mi (35 km) east of Seattle. Located just below the Snoqualmie Falls, the power plant consists of two power houses, Plant 1 and Plant 2. Plant 1 was completed in 1899 and is located underground. It is the first completely underground hydroelectric power plant ever built in the world. Plant 2 was built in 1910 and is located along the right bank of the Snoqualmie River. Both plants receive water from a small reservoir created by a weir atop the falls. Plant 1 has an installed capacity of 13.7 MW and Plant 2 a capacity of 40.2 MW for a total installed capacity of 53.9 MW, enough to power 40,000 homes.

<span class="mw-page-title-main">Pupu Hydro Power Scheme</span> Historic power station in New Zealand

The Pupu Hydro Power Scheme is a small hydroelectric power station near Tākaka in the Golden Bay region of the South Island of New Zealand. It opened in 1929 as the first power station in the region and was the first public electricity supply in Golden Bay. After closing in 1980 following damage to the generator, the power scheme was fully restored by the local Pupu Hydro Society and many volunteer groups over the course of seven years and re-opened in 1988, again supplying electricity to the national grid.

The Uma Oya Hydropower Complex (also internally called Uma Oya Multipurpose Development Project or UOMDP) is an irrigation and hydroelectric complex in the Badulla District of Sri Lanka. Early assessments of the project date back to 1989, when the first studies was conducted by the country's Central Engineering and Consultancy Bureau. The complex involves building a dam across Dalgolla Oya, and channelling water over a 3,975 m (13,041 ft) tunnel to Mathatilla Oya, both of which are tributaries of the Uma Oya. At Mathatilla Oya, another dam is constructed to channel 145,000,000 m3 (5.1×109 cu ft) of water per annum, via a 15,290 m (50,160 ft) headrace tunnel to the Uma Oya Power Station, where water then discharged to the Alikota Aru via a 3,335 m (10,942 ft) tailrace tunnel.

Nenskra Hydro Power Plant is a proposed hydroelectric power station to be located on the southern slopes of the Central Caucasus mountains in Svaneti, Georgia.

<span class="mw-page-title-main">Erathna Mini Hydro Power Project</span> Dam in Ratnapura, Sabaragamuwa Province

The Erathna Mini Hydro Power Project is one of the run of river mini hydro power projects in Sri Lanka which has the install capacity of 10 MW. The project is located on the Kuru Ganga, a tributary of the Kalu Ganga.

The Moragolla Dam is a planned hydroelectric dam in Moragolla, Sri Lanka. The dam is to be 35 m (115 ft) high and is planned to create the 1,980,000 m3 (70,000,000 cu ft) Moragolla Reservoir with a maximum supply level at 548 m (1,798 ft) MSL. Upon completion, the Moragolla Power Station would have a gross installed capacity of 30 megawatts from two francis turbines, capable of generating approximately 85 GWh annually.

The Mangorei Power Station is a hydroelectric power facility near Mangorei in Taranaki in New Zealand which makes use of water from the Waiwhakaiho River and the Mangamahoe Stream catchments.

St. Anthony Falls in Minneapolis, Minnesota, is the only natural falls on the Mississippi River. Since almost the beginning of settlement in the area by European descendants, the St. Anthony Falls have been used for waterpower. The first allowed settlers were at Ft. Snelling, where construction began in 1820. A sawmill was operating 1821 and a flour mill in 1823. As soon as the land at the sides of the falls became available it was purchased with the intent of using the waterpower of the falls. First lumber mills covered the falls, cutting lumber floated down the Mississippi. After 1870 flour mills started to dominate the area. From 1880 to 1930 the area was the number one flour producer in the US. In later years, some of the power came from steam, but in 1923 half of the waterpower used was for flour milling. Other industries have also used the waterpower.

Daraundi A Hydropower Station is a 6 MW run-of-river hydro-electric plant located on the Daraundi River in the Gorkha District of Nepal.

Daram Khola-A Hydropower Station is a run-of-the-river hydroelectricity plant located in Baglung District of Nepal. The flow from Daram River is used to generate 2.5 MW electricity.

Upper Mai-C Hydropower Station is a 6.1 MW run-of-the-river hydro-electric plant located in Ilam District of Nepal. It is powered by water from the Mai Khola.

Kabeli B1 Hydropower Station is a 25 MW run-of-river hydro-electric plant located in Panchthar District of Nepal. The promoter and operator, with a 20% share, is Arun Kabeli Power Limited (AKPL), a subsidiary of Arun Valley Group.

Rudi A Hydropower Station is a run-of-river hydro-electric plant located in the Kaski District of Nepal that came into operation in 2019. The flow from the Rudi River is used to generate 8.8 MW electricity.

References

  1. 1 2 3 4 5 6 PDD http://cdm.unfccc.int/filestorage/G/D/4/GD4C0MVQBLJH536RYP8UKZWAS7OIT1/PDD.pdf?t=WFJ8bnFxczNufDBLMD1bNOa7ENiIkdC4Lfxi.{{cite web}}: Missing or empty |title= (help)[ permanent dead link ]
  2. 1 2 3 4 5 6 "Denawaka Mini Hydro Power Plant - Projects - Vallibel Power Erathna". Vallibel Web.
  3. "Annual Report 2009-2010" (PDF). Annual Report 2009-2010. Archived from the original (PDF) on 2010-11-22. Retrieved 2015-07-06.
  4. 1 2 "PUCSL" (PDF). PUCSL. Archived from the original (PDF) on 2015-09-24. Retrieved 2015-07-06.
  5. "DFCC Annual Report" (PDF). DFCC Annual Report.
  6. "DFCC Annual Report 2" (PDF). DFCC Annual Report.
  7. 1 2 "CEB web". CEB web. Archived from the original on 2015-07-15.
  8. 1 2 Report.pdf?t=cDl8bnFxczY1fDBy1JeBnZTiDuYr7l6IO_ct "Validation Report" (PDF). Validation Report.{{cite web}}: Check |url= value (help)
  9. "Annual Report 2012-2013" (PDF). Annual Report 2012-2013.
  10. "Annual Report 2013-2014" (PDF). Annual Report 2013-2014.
  11. "CDM registered project". CDM registered project.