Factors for Primary Energy Efficiency and CO2 Emission of Geothermal Power Production

Abstract

The aim of the study is to produce standardized factors for primary energy efficiency (PEE) and CO2 emission for geothermal power production. These factors, or energy performance indicators, have been developed for different types of power production methods as a form of comparison on greenhouse gas emissions and how much primary energy is needed per kWh delivered to consumers. The calculation of these factors for geothermal energy utilization has had little attention while factors for many other types of energy conversion technologies have been developed and published during the last years. The focus of this study is to calculate the primary energy (PE) and CO2 factors for geothermal based power production based on data from the Helisheidi power plant in South-West of Iceland by using methods of life cycle assessment (LCA). The method of LCA provides a holistic approach to evaluate the total impact on environment and on consumption of primary energy and natural resources. Preliminary results on the primary energy factor for Hellisheidi geothermal power plant is found within the minimum/maximum range of 2.7 to 9 kWh primary energy per kWh electricity produced and the CO2 emission factor is calculated to be in the minimum/maximum range of 35 – 45 kg CO2 equivalents per produced MWh. More detailed factors need to be calculated with a more extensive life cycle analysis including all processes within the life cycle of the power plant.