Planning of geothermal projects in Iceland

Abstract

Geothermal energy supplies about 65% of the primary energy used in Iceland. The most important use is for space heating but geothermal power production is increasing rapidly. Exploration and development of the geothermal fields are divided into several phases starting with preliminary studies and continuing with appraisal study, project design, construction and operation of a power plant. Earlier the development strategy was to fully utilize the generating capacity of each field in one“large” power plant. This meant that the generating capacity of the field had to be known prior to the decision on the installed capacity of the power plant to be built. This strategy required an immense effort in exploration and testing to determine the optimum generating capacity of a field, requiring a large investment in exploration, drilling, reservoir testing and monitoring. A multi-step strategy is considered more suitable and more cost-effective for geothermal development than one large (full) step strategy. Stepwise development means that the geothermal field is developed in relatively small (20-50 MWe) steps. The response of the reservoir to this production is then monitored and evaluated and used for deciding if and when the next development step is taken. In this way, the power plant is in operation (and earning money for its owners) while the field is being tested. Stepwise development of geothermal resources has been applied in Iceland during the last 15-20 years.