“This transaction represents a significant step forward for our geothermal assets in Chile and Peru” said John Carson, Alterra’s CEO. “EDC is a strong partner with deep expertise, and we're pleased to be making this next step together.”

EDC will have six months to carry out field work and due diligence on the South American projects in order to elect to advance them into a formal joint venture.

The Mariposa geothermal power project is located in the Andes mountains of Chile and lies approximately 300 kilometres south of Santiago. It is comprised of the Laguna del Maule and Pellado concessions, which total 104,000 hectares and completely encompass a geothermal system that has an inferred estimate of 320 Megawatts. Alterra says it has conducted extensive exploration and infrastructural work at Mariposa, including three slim-hole wells and a 26 kilometre access road.

Alterra's early-stage geothermal projects in the southern volcanic belt of Peru include the Loriscota, Crucero and Panejo concessions in the north-eastern trend, and the Sara Sara and Tutupaca Norte concessions in the south-western trend. Initial indications and Alterra's exploration activities to date have supported the potential presence of large geothermal resources.

EDC has been developing and operating power plants since 1977 and its operating portfolio of 11 geothermal power plants and two hydro facilities totals 1,262 megawatts of capacity, producing over 3,600 gigawatt-hours in the first half of 2012. EDC has been actively expanding its project portfolio to Indonesia, Peru and Chile.