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Spain & Portugal Could Survive Just On Geothermal Energy

A version of this article was originally published on Sinc in Spanish.
By Luis Gonzalez



Spain could obtain all the energy the country needs just from the heat under the ground. No solar, no wind is needed. Nor from the old nuclear plants the Spanish government and the electric companies want to restart. There is the potential to produce up to 700 GW, but currently none is produced by this means.

The resource is geothermal power, a growing market that hasn’t reached the Iberian Peninsula yet, and is barely used in Europe. A new study from the University of Valladolid (UVa) published in the journal Renewable Energy with the title “An estimation of the enhanced geothermal systems potential for the Iberian Peninsula,” highlights the big capacity of Spain and Portugal to benefit from this natural resource.

The idea of geothermal energy is very simple; use the heat of the Earth to boil water, like any nuclear or thermal plant does, and use the steam to produce electricity. 24 hours a day, constantly. The heat is coming from the core of the planet, where the temperature is approximately the same as at the surface of the Sun (5,430°C). That is 6,371 kilometers under your feet, but in some areas of the so called Earth crust, the temperature might get up to 370°C due to portions of the mantle convecting upwards.

And there is the potential of the Iberian Peninsula, areas where the temperature reaches high values at shallow depths. According to the study, the areas of Galicia, western Castilla y León, the Sistema Central mountains, Andalusia, and Catalonia have the greater geothermal potential because at a depth of between 3,000 and 10,000 meters the temperature exceeds 150°C, and that is enough to get a geothermal plant to work.

The big number is 700 GW. Five times the current electrical power installed in Spain. This is obtained from calculations that consider wells with a depth between 3,000 and 10,000 meters and by means of enhanced geothermal systems (EGS). Although hard to get there, this depth is in the range of oil perforations. The number goes down to 190 GW for a maximum depth of 7,000 meters and 30 GW above 5,000 meters. To touch a sore spot, there are currently demonstrations in the Canary Islands (Spain) against offshore drilling for oil. The depth estimated for this perforation is 3,500 meters.

But there is something evil behind “enhanced” geothermal system. Enhanced means “to inject a fluid (water or carbon dioxide) under pressure” into a dry rock, creating fractures where the water is stored and heated up. Then, the hot water under pressure is extracted and cycled through a heat exchanger system (aka binary geothermal system) where electricity is produced. So, is this a kind of fracking?

Technically, it is, although it won’t be a legal problem in the case of Spain, since fracking is not forbidden there. In terms of water contamination and spills, it is believed that EGS uses a less aggressive technique based on degradable chemicals and lower pressure, and that the water reservoir is made, in principle, in a hot dry rock with no access to natural water resources.

In any case, more studies should be carried out to address this concern before annoying mother Earth, since another problem, also blamed on fracking, that has been reported from EGS is earthquakes. In 2009, Switzerland resolved to cancel an EGS plant in Basel after several studies stated that the enhanced seismic activity in the area was generated by the EGS power station. It must be said at this point that the plant in Basel was constructed on a known seismic fault.

The alternative to EGS is to exploit geothermal energy in a sustainable way, harnessing the heat that reaches the crust naturally. In that case, Iberia could profit from 3.2 GW of capacity. “It seems low, but it is the equivalent to three nuclear plants,” César Chamorro has declared, who is one of the authors of the study.

In a scenario where EGS could be put into practice without major risks, the main problem relies on the need of appropriated perforation techniques, a technical issue the oil companies are investing a lot of money and efforts to improve. They might be digging, literally, their own grave.

The authors have made use of the information collected in the Atlas of Geothermal Resources in Europe and surface thermal data available from NASA to publish this report and another paper in the journal Energy with the title “Enhanced geothermal systems in Europe: An estimation and comparison of the technical and sustainable potentials,” offering a similar study for Europe.

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