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Following my trip to offshore Portugal (Azores archipelago), this article is meant to direct our spotlights on São Miguel island which is in an Energy Transition phase. The Azores archipelago consists of nine Portuguese islands in the middle of the Atlantic, located two hours away from Lisbon by plane.

Its geological features and its location in a subtropical climate turn São Miguel to be a dream destination lost in the Middle of the ocean. Many of its natural reserves I visited gave me the feeling of being the new Indiana Jones. A real privilege!

Travel 3 in 1:

  • Exploring the unknown
  • Enjoy the nature (luxuriant forest, volcanoes, hot springs > 40°C)
  • Highlight the local power production from the Fogo volcano (Geothermal)

The population of São Miguel have made a huge progress towards energy self-sufficiency. Local power production is largely based on geothermal energy. This energy is mastered by one local company : EDA RENOVAVEIS. I had the chance to meet them and I want to thank them for having received me.

Here is my summary that I am sharing with you following a couple of interviews on the fly; guided tour of geothermal plants and the discovery of the natural signs of the geothermal activity at the surface.

What do the Azores and Caribbean archipelagos have in common ? What to remember about the São Miguel island, which is only a few steps away from energy self-sufficiency? What are their prospects for the future?



With almost 150,000 inhabitants for 745 Km2, São Miguel is an island barely visible on most of the world maps. Never mind! This nation is already one of the pioneers mastering renewable energies. Thanks to the production of electricity from “Fogo” (their volcano), São Miguel has a considerable lead in the rush towards the Energy Transition.


 The exploitation of the geothermal potential in São Miguel is possible thanks to the intense volcanic activity in the region. The archipelago is located on the Mid-Atlantic ridge. The nine islands of the Azores archipelago are volcanic, with volcanoes that can reach up to 2,351 meters above the sea level. This natural condition allows the development of geothermal energy at very high enthalpy. If you have read my previous articles about green energy types, then you know the virtues of geothermal (if you have not, please click here). This pearl for a successful Energy Transition is available 24/7, independent of weather conditions.


With nearly 150,000 inhabitants, it is clear that the energy needs of the island of São Miguel are not equivalent to what is required in the largest islands of the Caribbean like Martinique with its 385 551 inhabitants. Nevertheless, the energy demand in São Miguel is real.

The island is facing some issues, that are also encountered in the Caribbean islands :

  • Insularity : zone made up of non-connected islands (Non-Interconnected Zones)
  • High energy dependency: dependent on the import of hydrocarbon for power production
  • Local economy impacted by change in oil price
  • Costly infrastructure for energy supply

Early 70’s


This success did not happen overnight. The discovery of the geothermal potential happened in the early 70’s when exploration activity started.

Today, two geothermal plants are located on the northern flank of the Fogo volcano. Their combined production capacity reaches 23 MW (Ribeira Grande-13 MW & Pico Vermelho-10 MW). That represents 43% of the island’s energy needs. A great success!


With such a successful story, the government of the Azores are still keeping their ambitions at a higher level. By 2020, the share of renewable energies across the archipelago would reach 60%. Geothermal energy is about to be at the core of the energy mix targeted.

In São Miguel, a 5 MW geothermal power increase is planned. In the neighboring island (Terceira), the construction of a 3.5 MW geothermal power plant is underway. Ideally, those two islands would have insured energy supply for the smaller islands nearby, but such a project would represent a substantial technical achievement. Such a project is not yet into the agenda.


The aquifer corresponding to a naturally fractured reservoir is heated at 2 Km deep by the magmatic chambers (at around 200°C). The hot water is brought up to the surface by a production well. The water conveys the heat from the Earth to the surface. The heat of the steam is exploited in the “Heat Exchanger” where the heat is being transferred to another working fluid, (the pentane, organic fluid), which reacts quickly with temperature variations. At high temperature, the pentane vaporizes with the sufficient pressure that will force the turbine to rotate. The turbine’s rotation being necessary for electricity production. The hot water extracted from the subsurface cools down in contact during the process (at around 90°) and is then re-injected into the geothermal reservoir (recycling).

This system is called Binary system as two main fluids are engaged in the system (Water & Pentane).

On the photo below, I stand in front of the Production Well n°4 providing the Pico-Vermelho plant located a few hundred meters away:


  • Acceptance by the population

It is well known : the unknown scares! Geothermal energy is spreading more and more throughout the world over the years. Nevertheless, it remains very unpopular. (For you who read my articles, this is obviously not your case!). In addition, the use of geothermal energy may be linked to seismicity. In São Miguel, the area is naturally affected by the seismicity – as it is located on three tectonic plate boundaries. Therefore, it is difficult to directly link the geothermal exploitation to the seismicity.

  • Exploitation in preserved natural environments

There are many protected areas on the island. Most areas with a high geothermal gradient are characterized by outstanding geological features and beautiful landscape like hot springs. Such areas are an attraction for the tourists who contributes strongly to the local economy. It is difficult to design a geothermal plant in a protected area enjoyed by tourists. Although the development of geothermal energy is a real asset for the inhabitants of São Miguel, the location of the plants must be carefully chosen.

  • Financing

As geothermal is not so popular, it can be quite challenging to find investors to develop such colossal projects on small islands. The financial risk is directly linked to the geological uncertainties existing few kilometers deep.


Is it possible to concile energy production for industrial use with the preservation of the environment? The answer is absolutely YES! The development of Geothermal in São Miguel is an example. The endemic species of the forest in the vicinity of the geothermal plants are indicators supporting the idea that geothermal exploitation is eco-friendly.



– Savings on imports of petroleum products (38 000 tones in 2015)
-Use of a local energy resource available 24/7
– Strengthen the local economic system. Buying foreign commodities corresponds to a liability. By producing their own geothermal energy, the inhabitants have built up an asset. 


-Developing the diversification of energy sources
-Fast moving towards energy self-sufficiency (44% of energy needs in São Miguel was covered by Geothermal energy in 2015)
– Protection of the Azores from uncontrollable factors such as changes in oil prices and fluctuations in exchange rates with the US Dollar
-Improves recognition of the Azores throughout the world. Showing their success story on proves it.


– Contributes to the reduction of greenhouse gas emissions. In 2015, Electricity from geothermal energy in São Miguel has prevented the release of 146 000 tonnes of CO2 into the atmosphere
-Reduction of the combustion of raw materials (coal, oil or natural gas)
– I personally noticed, the geothermal plants are in perfect harmony with nature


-Geothermal creates jobs in a high-tech industry
-Developing technical skills locally


Common points and points and discrepancies

As you can see, the energy situation in the Azores Archipelago is very similar to the one of the Lesser Antilles. Their evolution over the past 50 years is spectacular and there is much to learn from their progression. Especially regarding their know-how when dealing with geothermal to rich a significant level of energy self-sufficiency.

Is it possible to duplicate their model? Probably not on every aspects, based on the differences that lies between the two archipelagos. For example, the national cohesion that exists in the Azores. This cohesion is creating a synergy within the archipelago. The current development of the geothermal power plant in Terceira (second most important island of the archipelago) is supported by the expertise gained in Sao Miguel. This National cohesion cannot be observed in the Caribbean islands, where several nations exist (Dominica, Guadeloupe, St. Lucia, Martinique, St. Kitts & Nevis, Grenadines etc.). Although, I remain convinced that this international aspect is a strength.

Another important point is that the population in the Caribbean islands is larger, and its consumption habits are much more energy demanding than the Azores’ population.

Despite these differences, the energy model of the Azores archipelago is very similar to the model to be developed in the Caribbean. It is naturally that the Azores deserve its dedicated post here on

Thanks to Hania, Thiago, Maria & Mr. Carlos BdP who have made a great adventure from this trip.

Thanks for reading !

Stay Tuned!


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