Two geothermal power plants, built with assistance from the ERDF, have demonstrated that volcanoes are a source of endogenous energy for the Azores. The safe and clean energy they provide has the potential to compensate for the very remote location of these islands.
- 01 September 2006
Context
Emerging from the ocean at the intersection of three tectonic plates (the American, African and Euroasian), on the Mid-Atlantic Ridge in a zone where the Earth’s crust is at its thinnest, the Azores archipelago is the site of intense volcanic activity to which it owes its origins. This peculiarity is also an opportunity for this most remote and economically disadvantaged region whose nine islands stretch over 600 km at a distance of 1 500 km off the coast of mainland Portugal.
The Azores enjoy privileged access to an inexhaustible energy source in the interior of the Earth: geothermal energy. These very high temperature geothermal fields are found only under certain geological conditions. Given the reliance of these islands on imported energy and the high cost of infrastructures - including for electricity - due to their geographical isolation and dispersed population (240 000), volcanic energy is a natural response to the needs of the Azores in this sector.
Growing power
It was prospecting carried out in 1973 by university students close to Ribeira Grande, on the northern slopes of the Fogo volcano, on the island of São Miguel, that first revealed the site’s high geothermal gradient (*).Since then, a number of scientific studies and thermometric drillings have confirmed the existence of a major geothermal reservoir at a depth of over 800 metres. An initial power plant, built in 1980 in Pico Vermelho, served as a pilot project for converting the geothermal energy into electricity.
The move to industrial production was under the aegis of the Geothermal Company of the Azores (SOGEO) S.A., founded in 1990 as a subsidiary of the Azores Electricity Company (EDA). In 1994 the first phase of the Ribeira Grande geothermal power plant project was completed, in the Cachaços-Lombadas region, with the installation of two turbogenerators with a unit power of 2.5 MW, followed in 1998 with the construction of two other units of 4 MW each. During this time the project was supported by the European REGIS programme for the most remote regions. A new power plant is currently being built at Pico Vermelho, replacing the former plant and increasing the power by 10 MW. That brings total present capacity of the Ribeira Grande / Pico Vermelho geothermal complex to 23 MW.
Results
The two projects have demonstrated it beyond all doubt: through the reliability of the technology employed and the economic viability of its operation, geothermics is the most promising renewable energy source for the Azores and the one best able to reduce dramatically their energy dependence. By its very nature it is spared the price fluctuations of fossil fuels. Continuously available, unlike wind power and solar energy it is not subject to meteorological conditions. In 2007, geothermics is expected to be delivering 161 GHw, which is 38% of the archipelago’s electricity supplies.
Another project, managed by the company GeoTerceira S.A., is currently at the study stage on the island of Terceira where research has also revealed a major geothermics potential, and prospecting is in progress on other islands. The combined output of all the projects currently being prepared by SOGEO and GeoTerceira suggests a production increase of up to about 275 GWh/year from 2010.
Requiring highly skilled human resources, geothermics favours the development of a regional skills centre. In terms of employment, in addition to the 80 persons employed in the construction of the two power plants, 25 direct jobs have been created to date.
Another consideration is that this energy source is totally clean, with zero polluting emissions. For a region renowned for the exceptional quality of its environment, this is a further major asset.
(*) Geothermic gradient: rate of temperature increase of the rocks in relation to increasing depth.