La Confluencia Hydro Project

Many hold copper to be Chile's most valuable resource, but when Pacific Hydro realised the full potential of the Tinguiririca River, we knew we'd uncovered something with an even greater lasting value.

The Tinguiririca's river flows are extremely reliable thanks to snow melt, glacial melt and rainfall. From our Chile office, we signed an agreement to acquire the water rights of the upper Tinguiririca River above 670 metres in elevation.

Since then Pacific Hydro has been developing two projects with a total of 313MW in generation capacity - the 155MW La Higuera Hydro Power Project and  upstream the 158MW La Confluencia Hydro Power Project.

How La Confluencia will operate

Our La Confluencia project, being developed with our joint venture partner SN Power of Norway, is located between the Tinguiririca and Azufre Rivers, about 140 km from Santiago, at an elevation of 1430 m. The Tinguiririca intake comprises a low pondage weir and an on-channel reservoir from which a canal and a tunnel will convey water to the junction point with the Azufre tunnel.

The Azufre branch will have intakes on the Portillo and Azufre Rivers, connected by a system of canals and tunnels delivering water to the Tinguiririca tunnel junction. The combined flow, enhanced through several small diversions, will continue to a surge shaft at the downstream end of the tunnel and, from there, through a relatively short channel to a surface power station on the left side of the Azufre River.

The power station will contain two 77,5MW Voith 89522 turbines and generators that are essentially similar to those in La Higuera, but with a slightly smaller capacity because of the lower head (344m). A 16 km long transmission line will connect the project to the La Higuera switchyard and construction on the project is expected to be completed during 2010.

Widespread Support

The two-stage run of the river project has been well supported by the Chilean national energy authority, Comision Nacional de Energia, and also by regional and local political and community groups. Emission-free hydro power projects are favoured locally as environmentally sensitive energy alternatives and as major providers of employment for local communities, many of whom have skills in underground works from the locally dominant mining industry.

The project also fits perfectly with the region's flourishing existing tourism, wine and agricultural industries and provides a means of opening up the rugged mountain area for further tourism development.