An interesting project underway in Nijar, lead by a group of engineers, is creating a system of Geothermal Energy to provide stable temperatures for the invernaderos of the municipality. This would allow them to substantially increase production for what would be, after five years amortisation of the project, essentially with free energy.
The secret is basically a 1,500 meter pipe dropped vertically into the earth, which would provide warm thermal water at the surface, capable of generating free electricity. The theory of geothermal energy as a free source of renewable energy is clear enough - we have, for example, all seen geysers and hot springs: this is water heated by the earth's crust. Geothermal energy is described as '...cost-effective, reliable, sustainable, and environmentally friendly...'. (Wiki).
The project has the backing of the Junta de Andalucía