[ad_1]
The Ethiopian government has set a goal of providing access to electricity to all of its citizens by 2025. It still has a long way to go, but projects like the Genale Dawa III hydroelectric plant are helping it get closer to the goal. That is one of the reasons why Genale Dawa III is a POWER Top Plant. (POWER Magazine)
POWER Magazine
Africa’s population is among the fastest growing and the youngest in the world. The International Energy Agency (IEA) has reported that 1 in 2 people added to the world’s population between now and 2040 will be in Africa. The continent is expected to overtake China and India and become the world’s most populous region by 2023. By some estimates, more than 500 million people are expected to join Africa’s urban population by 2040.
Let’s take a moment to digest that. New York City, which includes the boroughs of Brooklyn, Queens, Manhattan, the Bronx, and Staten Island, is the most populous city in the US Its population was estimated at 8,336,817 in 2019. That basically means, on average, three cities The size of New York City will be added to Africa every year from now until 2040. Of course, those people will eventually be added in a less conspicuous way in many cities across the continent rather than in new cities the size New York, but the magnitude of population growth is staggering.
The reason that is important to the energy industry is because the growing urban population means a growing demand for energy. According to IEA data, more than 510 million people in sub-Saharan Africa still do not have access to electricity today. Despite progress in some countries, current and planned efforts to provide access to modern energy services have barely outpaced population growth.
Ethiopia is a good example. More than 50 million people in Ethiopia, a population of 110 million, lack access to electricity. Still, the IEA cited it as a country that has made progress. While actively pursuing rural electrification for years, Ethiopia officially launched its National Electrification Program in November 2017, which aims to achieve 100% electrification by 2025. Significant additions of generation capacity will be needed to help meet that goal. The IEA reported that approximately 1 GW of geothermal power and 2 GW of wind power are expected to be added by 2030, but the key component of the electrification effort revolves around hydroelectric power. Around 22 GW of hydropower is expected to be added in the next 10 years.
Overall length III
The Genale Dawa III (GD-3) hydroelectric project, located in southern Ethiopia on the Dawa River, about 630 kilometers (km) from the capital Addis Abada, is one piece of the puzzle. The project is owned and operated by Ethiopian Electrical Power (EEP). Stantec provided engineering, procurement and construction (EPC) contract management consulting services.
GD-3 has an installed capacity of 254 MW (Figure 1). Three vertical Francis turbine generators, each with a generation capacity of 84.7 MW, are housed in a large underground cavern, while the transformers are housed in an adjacent one, with power cables extending to a distribution yard. external through an inclined tunnel.
1. The Genale Dawa III power plant has three units with a combined capacity of 254 MW. Courtesy: Stantec
The Concrete Lined Rock Fill Dam (CFRD) is 110 meters (m) high with a crest length of 456 m. The volume of the rock fill is about 3.22 million m3. The gated spillway comprises an ogee section that leads to a 250 m long ramp that ends in a collapsible bucket, designed for a maximum discharge of 1,880 m3 / second. Three radial gates, 6 m wide by 9,065 m high, were installed to keep the reservoir level at a height of 1,120 m above sea level and release large floods when they occur, most years.
During the construction of the dam, a diversion tunnel handled the river flow. It was 500 m long, 9 m high by 7 m wide, designed to withstand flows of up to 813 m3 / second under a height of 94 m.
A 60 m high power intake structure was built on the left bank of the river, some 600 m upstream from the dam. Includes a large vertical sliding door protected by garbage grates. It forms the entrance to the entrance tunnel, which is 12.4 km long and 8.1 m in diameter. A tunnel boring machine (TBM) was used to excavate 8.9 km of it, while the rest was done by traditional drilling and blasting in the very hard granite of the site.
The tunnel leads to a 120 m high buffer tank, and then to a 188 m deep concrete lined vertical shaft, 70 m concrete lined horizontal pressure tunnel (6.7 m diameter), lined gate 130 m (4.8 m) steel frame. m diameter) and a 2.6 m diameter collector leading to the power plant. The water returns to the river through a 768 m long, 6.7 m diameter drainage tunnel partially lined with concrete and a 480 m long open channel lined with masonry (or concrete where stability was a concern) .
Located on the GD-3 regulated main dam, the reservoir floods some 115 km2 of land. Outside of this, some 70 km2 were swamps, and most of what was left was covered by rainforest and shrubbery, most of which was cleared before the reservoir was filled.
An international list of project participants
The pre-feasibility and feasibility studies of the GD-3 hydroelectric scheme were carried out by Lahmeyer International (LI) of Bad Vilbel, Germany, in association with Yeshi Ber Consult (YBC) of Addis Ababa, Ethiopia. The construction of the project was carried out by CGGC (China Gezhouba Group Co. Ltd.) through an EPC contract. The turbines and generators were manufactured and installed by Dongfeng Electric Co. of China. TUNNELPRO, formerly known as SELI, an Italian supplier of underground equipment for the mining and construction industry, provided the TBM equipment through its Chinese subsidiary.
Stantec was appointed as the employer representative, providing contract management consulting services for the EPC, including services during the “period of liability for defects”. The company also facilitated “knowledge transfer” and “training through observation”, including field activities, mentoring, coaching and classroom workshops with professionals. An important way that Stantec helped improve the capabilities of EEP managers was by organizing a formal two-week management and technical training program in Chicago, Illinois for nine of the EEP leaders.
The first contract, which was for the pre-feasibility and feasibility studies of the GD-3 hydroelectric scheme, was signed between the Ethiopian Ministry of Water Resources and the consultants in 2003; the feasibility report was published in August 2007.
The EPC construction contract was signed on September 23, 2009, but work on the site did not begin until mid-March 2011. TBM excavation began in late August 2013 and was finally opened to complete excavation of the race tunnel in October. .29, 2016, after drilling some very hard gneiss, schists and granites, as well as isolated highly fractured areas.
Construction of the dam and spillway began in January 2013. The dam was completed in September 2016, while the spillway was completed in January 2017. Initially, it was planned to seize the reservoir in February 2017, but delayed two years even compensation for resettlement concluded the negotiations. The embargo finally began on February 28, 2019.
Although exact labor force statistics are difficult to quantify due to the number of contractors and the length of work, Stantec Ethiopia’s business and operations manager Aklile Gessesse said that at its peak, some 450 Chinese workers and 800 Ethiopians contributed to the success of the project. Stantec field staff had an average of four to five expats on site and 12 Ethiopian engineers throughout the project.
Challenges encountered
The remoteness of the site made staffing a challenge. “Training the future plant operators was one of the top priorities from the beginning of the project,” Gessesse told POWER. “From the beginning, our approach to technical capacity development put our local partners at the center of the process, allowing them to address their own concerns while Stantec provided advice and facilitated the process. Training was carried out throughout the process and the Stantec team took care to ensure a smooth transition. “
The length of the supply lines and the remoteness of the project were some of the many challenges the construction team faced. Some 8,300 km of sea separate Shanghai, China, where many shipments originated, and Djibouti, the receiving port. The equipment then had to be transported 1,300 km overland to the site. The site’s remote location also made communications difficult.
“The site’s remote location, poor internet service and lack of telephone lines were certainly a challenge for the project from the beginning,” Gessesse said. “As the project progressed, a mobile phone service was established, which greatly helped communication.”
Traveling was also a challenge. Helicopters were not allowed to fly to the project site for non-emergencies, and reaching the project from other parts of the world could take days. The closest hospital was a six-hour drive from GD-3, so the team developed an air evacuation plan in the event of a medical emergency.
“A major variation of the work was introduced early in the project, when it was decided to upgrade the project’s switchyard and transmission line from 230 kV to 400 kV,” Gessesse said. Negotiations on the increase in the cost of the work continued for several years and caused delays in construction.
The plant was officially inaugurated on February 4, 2020. The first two generating units began commercial operations in February and March 2020, respectively, and are now expected to be completed before the end of the year. While the project is still in its early operational stages, the first two units have performed well, operating at full capacity with virtually no problems for approximately six months.
“We are delighted with the first results,” Gessesse said, adding that the Stantec team plans to continue assisting EEP with testing and other support work until at least September 2021.
The completion of the GD-3 project will increase the overall electrical capacity in Ethiopia by nearly 6%, from 4,260 MW to 4,514 MW, contributing to the government’s goal of increasing national capacity to 12,000 MW by 2025. As such, the project is recognized as a POWER Top Plant award winner for, among other achievements, providing much-needed power to help electrify Ethiopia. ■
–
Join the conversation at Twitter and Facebook.
[ad_2]
