2.10 Groundwater-hydro development in Chile and Libya

Groundwater-hydro has been studied in two development projects in the arid regions of north-west Chile and the Sahara desert in Libya. The Chilean plan will involve constructing a high-pressure pipeline to exploit the height difference between the wellfield in the Andes and the coastal terrain. The Libyan plan will involve installing a mini-hydro station at the end of the Great Man-Made River pipeline to exploit the height difference of 200 m.

2.10.1 Groundwater-hydro in multi-purpose Salar del Huasco scheme in Chile

The coastal plains in the northern part of Chile may be classified as arid to extremely arid (fig. 2.50). The extremely arid Iquique region is located in the northern corner of Chile, where rainfall is only 10 mm or less per year. No water resources are available in these arid coastal regions except for a very limited amount of groundwater, whose quality is likely to be saline or brackish. By contrast, huge renewable groundwater resources with excellent quality can be tapped in the Andes mountain ranges. The hydro-potential of the Andes mountain ranges in South America is one of the world's largest, and includes both surface water and groundwater.

The Salar del Huasco project is being planned to develop groundwater for water supply, irrigation, and hydroelectric power. The groundwater-hydro scheme would use the substantial head difference between the wellfield on the mountain range (3,750 m) and the irrigation area on the coastal terrain (1,400 m). The water will be supplied from a wellfield 76 km away by a pipeline that will cross the mountains using pumping stations. The project will assure adequate drinking water supplies to Iquique until the middle of the next century and will increase the local availability of irrigation water by 50%. This will suffice for the cultivation of 4,800 ha of land on the extremely arid terrain. The hydro units will have a combined capacity of 50 MW (WPDC 1988).

Fig. 2.50 Salar del Huasco groundwater development scheme and wafer pipeline system in Chile

Fig. 2.51 Schematic profile of the Salar del Huasco groundwater-hydro scheme

The scheme will comprise the extraction of 2.4 m³ of groundwater per second from 54 wells in the area of Lake Huasco, which is at an elevation of 3,785 m. The water will be piped through a central collector to Iquique and Pica, and the available head will be used to generate electricity. The first or upper station will be built between the wellfield and Pica, at an elevation of 3,000 m, and the second or the lower station will be built in Pica, at an elevation of 1,400 m (fig. 2.51). The theoretical hydro-power is estimated to be 50 MW in total, 16 MW at the first power station and 34 MW at the second. The installed capacities of the power stations are preliminarily estimated to be 42 MW in total, consisting of 13 MW at the first station and 29 MW at the second.

2.10.2 Groundwater-hydro in the Great Man-Made River project, Libya

A hydroelectric power station will be installed in part of the massive Great Man-Made River project, which will carry an eventual 6 million m³ of water per day from beneath the southern Sahara desert for agricultural, industrial, and domestic use in the heavily populated coastal regions in Libya (see section 2.7.3 above). This groundwater-hydro plant will be the first of its kind.

The second phase of the project, begun in 1986, includes an option for an 18 MW hydroelectric station to be built adjacent to a terminal reservoir with a planned capacity of 28 million m³ (WPDC 1986). The station would use a differential head of water of some 200 m, and power output would compensate for the energy used to pump the water to the coast.