How do you build a geothermal power plant on a volcano, in a natural reserve, in the middle of the Atlantic Ocean? That’s exactly what Exergy, CME, and EDA Renováveis have done in the Azores…
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| Pico Alto geothermal plant in the Azores Islands (Exergy-orc.com) |
A technology which has increased the efficiency of geothermal power plants is the so-called binary cycle, employed in the recently inaugurated 4 MW geothermal power plant of Pico Alto, on Terceira Island in the Azores, located on a 2650-foot (808 meters) high volcano, 1500 kilometers away from the coast of Portugal in the Atlantic Ocean.
Binary cycle power plants use the heat from the underground geothermal reservoirs to heat up a fluid (in this case, cyclopenthane) with a lower boiling point than water, thus producing steam at lower temperatures than those needed in traditional geothermal power plants, which use water vapor. The steam is then driven into a turbine connected to a generator.
The great advantage of binary cycle power plants is that they work with lower water temperatures than those necessary in dry steam or flash power plants. In fact, while the latter need temperatures upwards of 347 °F (175 °C) to produce electricity, binary cycle power plants work with water temperatures as little as 185–194 °F (85-90 °C).
The Pico Alto power plant, built by Italian Exergy and Portuguese CME for the local energy provider EDA Renováveis, uses Radial Outflow Turbine technology to increase conversion efficiency, which has reached the highest possible level of 4.9 MW, with an average of 4.6 MW produced to supply the 56,000 island inhabitants, according to Exergy.
The Pico Alto power plant, built by Italian Exergy and Portuguese CME for the local energy provider EDA Renováveis, uses Radial Outflow Turbine technology to increase conversion efficiency, which has reached the highest possible level of 4.9 MW, with an average of 4.6 MW produced to supply the 56,000 island inhabitants, according to Exergy.
