power generation original project 1

power generation original project 2

The original project harnessed the power of the Nam Theun, using the run-of-the river TH dam at Ban Kengbit. Using a combination of radial gates, flap gate, and a weir, this dam diverted around 110 cubic metres per second of the river's flow down a 6-km tunnel to a ground-level powerhouse at Khounkham, in the Nam Hai valley. The water falls about 235 m and runs through two Francis Unit turbines with a total capacity of 240 MW (following upgrades in 2016-17). From here, an 86-kilometer transmission line to the border at Thakhek exports power to the Electricity Generating Authority of Thailand. From the TH Powerhouse, the water flows through a Tailrace Canal to a Re-regulating pond before joining the Nam Hai river, which runs first to the Hinboun and then the Mekong rivers.

The ADB has described the original project as "successful, bordering on highly successful", and says it "achieved its intended purpose". The project was able to reliably supply 1,400 GWh of electricity annually, supporting Lao economic growth through foreign exchange earnings, and the development of the central provinces through local power supply. For several years THPC was the largest foreign exchange source in Laos, helping the country to significantly reduce its current account deficit and contributing to the Government's ability to increase investment in education, health, and social welfare during the late 1990s and early 2000s.

At less than 2 US cents per kilowatt-hour, the cost of THPC generation has been very low. Dividends paid to the original Lao shareholder, EDL, did much to strengthen the utility's financial health, allowing it to greatly expand access to electricity across Laos and to enter contracts with investors for other hydropower developments. THPC's financial model and successful refinancing of the project 2002 helped ensure the sustainability of the project and to attract backers to the expansion plan. In summary, the ADB wrote of Theun-Hinboun, "The Project can serve as a model for effectively combining multilateral and bilateral aid, and establishing a successful public-private partnership that benefits the country".