Top 10 Largest Hydroelectric Projects in Vietnam

Sơn La Hydroelectric Plant is located on the Đà River in Ít Ong commune, Mường La district, Sơn La province, Vietnam. The plant has a installed capacity of 2,400 MW, with 6 generating units, groundbreaking on December 2, 2005. After 7 years of construction, the Sơn La Hydroelectric Plant was inaugurated on December 23, 2012, three years ahead of schedule, becoming the largest hydroelectric plant in Vietnam and Southeast Asia at that time. The project commenced in 2005 but thirty years prior, initial surveys were conducted by experts from the Moscow Hydropower and Industry Institute, the Electricity and Power Distribution Company of Japan, the Designing Research and Production Shareholding Company of Russia, and SWECO of Sweden. In 2001, the Sơn La Hydroelectric Project was approved by the National Assembly for investment, but the construction plan was not yet finalized. In December 2002, the feasibility study report was approved at the 2nd session of the XI National Assembly. The construction plan was also approved by the National Assembly with the goal of commissioning Unit 1 in 2012 and completing the entire project in 2015.

Main technical specifications:

• The normal water level of the Sơn La reservoir is 215 meters;
  
• Flood level: 217 meters;
  
• Dead water level: 175 meters.
  
• Reservoir area: 224 km2. Total reservoir volume: 9.26 billion cubic meters of water.
  
• Installed capacity: 2,400 MW, consisting of 6 generating units, each with 400 MW;
  
• Average annual electricity production: 10.2 billion kWh;
  
• Drainage basin area: 43,760 km2;
  
• Investor: Vietnam Electricity (EVN);
  
• Main contractor: Sông Đà Corporation.

In 2003, EVN completed the feasibility study report for the Sơn La Project. Resettlement work also began. In December 2003, the first group of Sông Đà Corporation workers arrived at the construction site to prepare for construction and simultaneously utilize the two-year site preparation period (2004-2005) to construct diversion works. On January 15, 2004, the Prime Minister issued Decision No. 09/QĐ-TTg approving the Sơn La Hydroelectric Project. In 2005, construction of the Sơn La Hydroelectric Project began. During the design and construction process, the project underwent numerous changes compared to the initial plan. On January 11, 2008, the first roller-compacted concrete blocks were produced. By August 25, 2010, the pouring of roller-compacted concrete for the main dam of the plant was completed. On December 23, the Sơn La Hydroelectric Project was officially inaugurated, becoming the largest hydroelectric dam in Southeast Asia, with an average annual electricity output of over 10 billion kWh, accounting for nearly one-tenth of Vietnam's electricity output.

Hòa Bình Hydroelectric Plant, located in Hòa Bình Province, on the Đà River in northern Vietnam, is the largest hydroelectric plant in Vietnam and Southeast Asia from 1994 to 2012 (overtaken by Sơn La Hydroelectric Plant in 2012). Constructed with the assistance of the Soviet Union (from 1991 to 1994, it was the Russian Federation), the plant began construction on November 6, 1979, and was inaugurated on December 20, 1994. Hòa Bình Hydroelectric Plant is the main power source for the entire national electricity system of Vietnam. In 1994, along with the inauguration of the plant and the construction of the 500 kV North-South power line from Hòa Bình to the Phú Lâm substation (Ho Chi Minh City), a national power grid was formed. This project significantly contributed to providing electricity to the southern and central regions of Vietnam. The plant supplies approximately 27% of the country's electricity. The Hòa Bình dam plays an important role in providing irrigation water for agriculture in the downstream areas, including the Red River Delta, especially during the dry season. It regulates the water level of the river while pushing saline water away from river mouths.

Main Technical Specifications:

• Hòa Bình Hydroelectric Plant has a design water level of 117 m.
  
• Reinforced water level: 120 m.
  
• Dead water level: 80m.
  
• The above parameters are measured in meters above sea level.
  
• Reservoir area: 208 km2.
  
• Total reservoir volume: 9.45 billion cubic meters of water.
  
• Installed capacity: 1,920 MW, comprising 8 generating units.
  
• Annual average electricity output: 8.6 billion kWh.
  
• The Hòa Bình Hydroelectric Plant has 12 spillway gates and 8 generating units.
  
• Each generating unit has a capacity of 240 MW.

At the traditional yard of the Hòa Bình Hydroelectric Plant, there is a truncated pyramid-shaped concrete block, on which a steel plaque engraved with the words: 'Where preserves the letter of those who built Hòa Bình Hydroelectric Plant to future generations. The letter will be opened on January 1, 2100'. The 'storage' of letters is actually a truncated pyramid-shaped concrete block (4 sides of a trapezoid) with a bottom edge of 2 meters, a height of 1.8 meters, and a top edge of 0.8 meters, weighing nearly 10 tons. After being approved by Prime Minister Phạm Văn Đồng and comrade Đỗ Mười, the leader of the Hòa Bình Hydroelectric Plant Construction Joint Stock Company invited several writers, journalists, and intellectuals to participate in writing the letter. However, Comrade Đỗ Mười also advised that since Vietnam does not have this tradition, the letter should not be 'buried' in the dam but should be placed in a dignified location. After discussions with Soviet experts, the leadership of the company decided to place the letter inside the concrete block. The current letter inside the concrete block is a collective work. After the letter was completed, a skilled calligrapher was assigned to copy two versions in Vietnamese and Russian using ink.

Đa Nhim Hydroelectric Plant is a hydroelectric project built on the Đa Nhim River in the area of D'Ran town, Đơn Dương district, Lâm Đồng province, and Lâm Sơn commune, Ninh Sơn district, Ninh Thuận province, Vietnam. Đa Nhim Hydroelectric Plant has an installed capacity of 160 MW with 4 generating units, commenced construction in April 1961, and completed in December 1964. It is the first hydroelectric project located at the highest cascade, exploiting the hydroelectric potential of the Đồng Nai river system, bordering between Lâm Đồng and Ninh Thuận provinces. The expansion project of Đa Nhim hydroelectric plant increased the total installed capacity to 240 MW. The installation of an additional 80 MW unit started in December 2015 and was successfully connected to the grid by December 2018.

Main Technical Specifications:

• Capacity: 240 MW.
  
• Annual electricity output: 1 billion kWh.
• Operating units: 4 generating units

Đa Nhim Hydroelectric Plant was commenced construction in April 1961 and completed in December 1964 with the sponsorship of the Government of Japan. The plant has a total installed capacity of 160 MW consisting of 4 generating units, producing an average annual electricity output of approximately 1 billion kWh. However, over time, the plant's equipment and transmission lines gradually rendered it unable to operate at full design capacity. In 1996, the Government of Vietnam decided to allocate $66.54 million for the refurbishment of equipment and transmission lines, including $48.6 million in concessional loans from Japan, $2.9 million in domestic counterpart funds, and the remainder from other international donors.

Thác Mơ Hydroelectric Plant is a hydroelectric project located in the valley of the Da River, in Lai Chau province, Vietnam. This project is constructed with the aim of providing renewable energy to meet the increasing demand for electricity in the country.

The Thác Mơ hydroelectric project is one of Vietnam's major projects in the field of renewable energy, named after the famous natural waterfall in the area, contributing to the majestic and unique natural landscape. It utilizes water from the Da River, one of Vietnam's important rivers, providing favorable conditions for hydroelectric energy exploitation. The Thác Mơ hydroelectric plant has a large capacity and is equipped with the most advanced technologies to optimize operational efficiency and minimize negative environmental impacts.

Main Technical Specifications:

• Capacity: 225MW.
• Annual electricity output: 662 million KWh.
• Reservoir capacity: 1.36 billion m3.
• Main dam height: 50m, width: 7m.
• Spillway length: 44m.

Construction of the Thác Mơ Hydroelectric Plant not only brings benefits in terms of electricity but also contributes to the economic and infrastructural development of the region, facilitating tourism and visits to this famous waterfall. However, like any large hydroelectric project, the construction of the Thác Mơ hydroelectric plant may face some controversies and impacts on the environment and local communities. Therefore, environmental management and monitoring during the project's operation are essential to ensure sustainability and protect natural resources for future generations.

Huổi Quảng Hydroelectric Plant or Huội Quảng Hydroelectric Plant is a hydroelectric project built on the Nậm Mu River in Khoen On commune, Than Uyên district, Lai Châu province, and Chiềng Lao commune, Mường La district, Sơn La province, in the northwest mountainous region of Vietnam. Huội Quảng Hydroelectric Plant has a installed capacity of 520 MW, an annual electricity output of 1.904 billion KWh, commenced construction in January 2006, and completed in May 2016. The project is one of the hydroelectric plants with large power generation capacity, part of the planned cascade hydroelectric system on the Đà River. Upstream about 27 km from the upper Nậm Mu River is the Bản Chát Hydroelectric Plant with a capacity of 220 MW, supplying water through an interconnected operation system, continuously supplying water to the Huội Quảng reservoir through the Bản Chát hydroelectric plant, ensuring sufficient water supply for power generation.

Main Technical Specifications:

• Normal water level: 370m.
• Dead water level: 366m.
• Power generation water head: 151m vertically.
• Downstream water level: 215m.
• Reservoir area: 2,824 km2.
• Average annual flow rate: 158.1 m3/s.
• Reservoir surface area: 870ha.
• Spillway tunnel diameter D=8.3m.
• Downstream pressure tunnel width 12.5m, length 37m, height 77.27m.
• Capacity at normal water level is 184.2 million m3.
• Reservoir area: 2,824 km2.
• Average annual flow rate: 158.1 m3/s.

When planning the hydroelectric plants on the Nậm Mu River in Sơn La, the name 'Nậm Mu Hydroelectric Plant' was given to a small hydroelectric plant with a capacity of 12 MW built in 2003 in Tân Thành commune, Bắc Quang district, Hà Giang province. Therefore, the Nậm Mu hydroelectric plants in Sơn La switched to using names based on geographical locations for the plants, such as Bản Chát Hydroelectric Plant, Huội Quảng Hydroelectric Plant... On the other hand, during the design phase, the dam of this hydroelectric plant was built at the location where the small stream Huổi Quảng flows into the left bank of the Nậm Mu River in Tàng Khê hamlet. When naming the hydroelectric survey project, it was recorded as Huội Quảng. However, some documents, such as the Nhân Dân newspaper, when writing about resettlement work, used the name Huổi Quảng hydroelectric plant, which is a name suitable with the original name in the Thai language.

Yaly Hydroelectric Plant is a hydroelectric plant on the Krông B'Lah River at the border of Sa Thầy district, Kon Tum province, and Chư Păh district, Gia Lai province, Vietnam. The Ialy hydroelectric plant has an installed capacity of 720 MW with 4 generating units, producing an average annual electricity output of 3.650 billion KWh. The project commenced construction in 1993 and was completed in 1996. The reservoir area is located at Ialy Waterfall on the Pô Kô River in Chư Păh, Gia Lai province. The Yaly Waterfall is one of the largest waterfalls in Vietnam with a height of 42 meters. The hydroelectric dam is a gravity dam with an impermeable core made of clay, with a crest elevation of +522.0 m, a crest length of 1,142.0 m, and a dam height of 71.0 m. The spillway consists of 6 gates, using radial gates. Each gate is 15m wide.

Main Technical Specifications:

• Installed capacity: 720 MW.
• Number of generating units: 4 units.
• Annual electricity output: 3.650 billion KWh.
• Dead storage capacity: 258.07 million m3.
• Active storage capacity: 779.02 million m3.

The reservoir of Yaly hydroelectric plant covers an area of 64.5 km2, with a dead storage capacity of 258.07 million m3 and an active storage capacity of 779.02 million m3, mostly located in Sa Thầy district, Kon Tum province, within the Pô Kô and Đăk Bla river basins. Like many other hydroelectric projects, the Ialy hydroelectric plant has been criticized for causing floods, damaging fisheries resources, and lacking consultations with Cambodian authorities. 59 villages in Northeastern Cambodia, supported by Oxfam, have collaborated with the Sesan-Srepok-Sekong Protection Network (3SPN) to promote environmental protection in the basins of these three rivers.

Sê San 4 Hydroelectric Plant is a hydroelectric project built on the Sê San River, located in the area of Mô Rai commune, Sa Thầy district, Kon Tum province, and Ia O commune, Ia Grai district, Gia Lai province. Originally planned by EVN, it is the final project downstream of the Sê San river system and the second-largest in capacity after the Ia Ly hydroelectric plant. The Sê San 4 hydroelectric plant has a capacity of 360 MW with 3 generating units, commencing construction in November 2004, completing in March 2010, and undergoing comprehensive acceptance in December 2012.

Main technical specifications:

• Capacity: 360 MW.
• Number of generating units: 03+.
• Dam type: Roller-compacted concrete.

As early as 2011, during the dry season in the Central Highlands, hydroelectric plants had to operate intermittently due to water shortages. The Sê San 4 Solar Power Project, with a capacity of 49 MWp, was constructed within the land area of the Sê San 4 Hydroelectric Plant in Gia Lai province. The project was fully funded by the French Development Agency (AFD) for the entire EPC contract value. On October 28, 2019, at the AFD headquarters in Paris, France, a credit agreement for the project was signed between representatives of the Vietnam Electricity Group (EVN) and AFD.

Trị An Hydroelectric Plant is constructed on the Đồng Nai River, flowing through Vĩnh Cửu district, Đồng Nai province, located 65 km northeast of Ho Chi Minh City. The plant was built with financial and technological support from the Soviet Union since 1984, with the first generating unit commissioned on April 30, 1988, and inaugurated in 1991. Trị An Hydroelectric Plant has 4 generating units, with a total designed capacity of 400 MW, and an average annual electricity output of 1.7 billion kWh. The Trị An reservoir is used for annual regulation purposes, designed to generate electricity with a normal water level of 62 meters, a dead water level of 50 meters, and a reinforced water level of 63.9 meters. The rated flow rate at the nominal capacity is 880 m3/s, corresponding to 220 m3/s per generating unit, with a net head of 53 meters. The hydroelectric plant was constructed with a total installed capacity of 4 units × 100 MW = 400 MW, generating an annual electricity output of 1.76 trillion kWh.

Main technical specifications:

• Capacity: 400 MW.
  
• Electricity output: 1.76 trillion kWh.
  
• Area: 323 km2.
  
• Volume: 2.76 trillion m3.
• Annual electricity generation: 1.76 TWh.

The flood discharge flow rate through the highest designed spillway is 18,450 m3/s. The main pressure line consists of a river closure dam and a spillway dam. The river closure dam is constructed of mixed earth and rock, with a length of 420m, a height of 40m, and a top width of 10m. The spillway dam is 150m long, with 8 overflow compartments, each 15m wide, equipped with 8 sliding gates operated by 2×125-ton gantry cranes. The main and auxiliary dams create a reservoir with an area of 323 km2 and a total volume of 2.76 trillion m3, with an effective storage capacity of 2.54 trillion m3 and a dead storage capacity of 0.218 trillion m3. The Trị An Hydroelectric Plant also holds comprehensive economic significance with the primary purpose of integrating into the national power grid alongside other plants to supply electricity to the entire country. Additionally, as a multipurpose hydroelectric plant, it ensures water supply for domestic, agricultural, saline intrusion prevention, and flood regulation purposes.

Hàm Thuận - Đa Mi Hydroelectric Plant is a hydroelectric complex located on the La Ngà River in the Dong Nai River basin. The plant is situated in Binh Thuan province with a capacity of 300 MW and 2 generating units. The reservoir of the plant spans Lam Dong and Binh Thuan provinces, covering an area of 25.2 km2 at the normal water level of 605 m with a volume of 695 million m3. The project features a tunnel system with a total length of 7,765 m. The main dam is constructed with earth and rock fill, standing at a height of 93.5 m and a crest length of 686 m. In addition to the main dam, there are 4 auxiliary earth-fill dams. Construction commenced in 1997 and the plant was operationalized in 2001.

Main technical specifications:

• Capacity: 300 MW
  
• Electricity output: 1.555 billion kWh
  
• Area: 25.2 km2
  
• Volume: 695 million m3.

Đa Mi Hydroelectric Plant is the downstream cascade plant of the Hàm Thuận Hydroelectric Plant, located 10 km downstream and approximately 200 km northeast of Ho Chi Minh City. The capacity of the Đa Mi Hydroelectric Plant is 175 MW. The total annual electricity output of both Hàm Thuận - Đa Mi plants as designed is 1.555 billion kWh. Besides power generation, the reservoirs also contribute to supplemental irrigation water and domestic water supply during the dry season for the downstream areas of the La Ngà River, particularly in Tánh Linh and Đức Linh districts of Binh Thuan province, while increasing the flow to the Trị An reservoir to enhance electricity generation for the Trị An Hydroelectric Plant. This is a cluster of plants under the Da Nhim - Hàm Thuận - Đa Mi Hydropower Joint Stock Company (including the Da Nhim - Song Pha plant with capacities of 160 MW and 7.5 MW, respectively).