Nam Theun 2 Dam: Laos's Landmark Hydroelectric Export Project

**Nam Theun 2 Dam** on the Nam Theun River in Khammouane Province, central Laos, is a **1,070 MW** hydroelectric project that became one of the most closely watched development experiments in the world. Completed in **2010** with World Bank support and private sector investment, the dam was designed as a model for how hydroelectric development could generate revenue for poverty reduction in one of Southeast Asia's poorest countries while meeting stringent environmental and social safeguards.

Introduction

The dam diverts water from the **Nakai Plateau**, a vast elevated wetland of extraordinary biodiversity, through a **39-meter** dam and headrace tunnel system to a powerhouse on the Xe Bang Fai River, 350 meters below. Approximately 95 percent of the electricity is exported to Thailand under a 25-year power purchase agreement, with the revenue channeled into Laos's national development budget.

Engineering & Structure

• Type: Concrete gravity dam + trans-basin diversion
• Height: 39 meters (main dam)
• Installed Capacity: 1,070 MW
• Turbines: 4 × 267.5 MW Francis turbines

Nam Theun 2 uses a relatively low dam (39 meters) on the Nakai Plateau to create a reservoir, then diverts water through a 350-meter drop via headrace tunnel and penstocks to a powerhouse on the Xe Bang Fai River. This trans-basin diversion design generates enormous power from a relatively modest dam by exploiting the dramatic elevation difference between the Nakai Plateau and the adjacent lowlands.

The powerhouse contains four 267.5 MW Francis turbines operated by a consortium of Electricité de France, the Lao government, and Thai investors (EGCO and Italian-Thai Development). The project cost approximately $1.3 billion, with financing from the World Bank, Asian Development Bank, and commercial lenders.

Geographic Setting

• River: Nam Theun River (Mekong tributary)
• Location: Nakai District, Khammouane Province, Laos
• Coordinates: 17.96°N, 105.23°E
• Reservoir Area: 450 km² (Nakai Plateau)

The Nakai Plateau is an elevated limestone and sandstone plateau at approximately 500 meters elevation, bordered by the Annamite Mountains to the east (the border with Vietnam) and a steep escarpment to the west dropping to the Mekong lowlands. The plateau was covered by a mosaic of evergreen and semi-evergreen forest, grassland, and wetland before the reservoir flooded approximately 450 square kilometers.

The plateau lies adjacent to the Nakai-Nam Theun National Protected Area, one of the most important conservation areas in mainland Southeast Asia. The protected area harbors populations of the saola (a critically endangered wild bovid discovered only in 1992), large-antlered muntjac, and other species found nowhere else on Earth. The dam's environmental framework includes extensive protections for this adjacent conservation area.

Hydroelectric Power

• Installed Capacity: 1,070 MW
• Annual Output: ~6 TWh
• Export: 95% to Thailand via 230 kV lines
• Revenue Model: Concession revenue funds Laos national development

Nam Theun 2 generates approximately 6 terawatt-hours per year, with 95 percent exported to Thailand under a 25-year power purchase agreement. Thailand's state utility EGAT pays approximately $300 million per year for the electricity, making the project one of Laos's largest sources of revenue. The remaining 5 percent is supplied to Laos's domestic grid.

Revenue from the project is channeled into Laos's national budget under an agreement requiring the government to spend specified amounts on health, education, and poverty reduction. The World Bank promoted this revenue-sharing model as a template for responsible resource development in poor countries, though monitoring the government's actual use of the funds has proven challenging.

Environmental & Social Impact

• People Displaced: ~6,200
• Biodiversity: Adjacent Nakai-Nam Theun protected area harbors saola
• Xe Bang Fai: Diverted water significantly altered downstream river

Approximately 6,200 people were relocated from the reservoir area on the Nakai Plateau, mostly from ethnic minority communities practicing swidden (shifting) agriculture. The resettlement program, designed under World Bank guidelines, provided new homes, community infrastructure, and livelihood support programs. While generally better managed than many dam resettlements, independent evaluations found that some relocated families experienced reduced income and food security.

The dam's trans-basin diversion fundamentally altered the Xe Bang Fai River, which receives the turbined water. The river's flow increased dramatically during dry season (when the dam generates at peak capacity), flooding riverside gardens and fisheries that local communities depended upon. An estimated 120,000 people along the Xe Bang Fai were affected by these downstream changes, prompting compensation and adaptation programs that have been only partially successful.

Key Facts

• Nam Theun 2 was designed as a World Bank model for responsible hydroelectric development.
• Approximately 95% of its 1,070 MW output is exported to Thailand.
• The Nakai Plateau reservoir covers 450 km² adjacent to critical saola habitat.
• The trans-basin diversion affected ~120,000 people along the Xe Bang Fai River downstream.
• Revenue of ~$300 million/year is channeled into Laos's national development budget.

Fun Facts

• The saola, sometimes called the "Asian unicorn," was unknown to science until 1992 and has never been photographed alive in the wild by a researcher — it lives in the forests adjacent to the dam reservoir.
• The World Bank's president personally championed Nam Theun 2 as proof that large dams could be built responsibly — the project became a test case for the institution's credibility on hydropower.
• Laos's strategy of becoming the "Battery of Southeast Asia" through hydroelectric exports has led to over 60 dam projects across the country, many on Mekong tributaries.

Final Thoughts

Nam Theun 2 Dam was designed as a proof of concept — showing that hydroelectric development could generate poverty-reducing revenue while meeting high environmental and social standards. The reality has been more complex, with genuine achievements in resettlement and conservation offset by downstream impacts and questions about revenue transparency. It remains a reference point for every major dam proposed in the developing world.