Miravalles geothermal field, the most important Costa Rican geothermal area, is located on the southwestern slope of the Miravalles volcano. The present development extends over an area of more than 21 km2; about 16 km2 are dedicated to production and 5 km2 to injection. The temperature of the water-dominated geothermal reservoir is about 240oC. Fifty-three geothermal wells have been drilled to date. They include observation, production and injection wells, with depths ranging from 900 to 3,000 meters. Individual wells produce enough steam to generate an average of 7MWe.

Commercial production of electricity using geothermal steam began at Miravalles in early 1994, when Unit 1, a 55MW single-flash plant, was commissioned. The following year, ICE completed the installation of a 5MW wellhead unit. Unit 2, the second 55MW plant, started production in August 1998. In March 2000, Unit 3, a 29MW single-flash private plant, started delivering electricity to the national grid, and finally Unit 5, a 19MWe binary plant, increased the total installed capacity at Miravalles to 163 MWe.