Life Cycle Assessment of the Theistareykir Geothermal Power Plant in Iceland
Alexandra KJELD, Helga Johanna BJARNADOTTIR, Ragnheidur OLAFSDOTTIR, Björn HALLDORSSON, Valur KNUTSSON
[EFLA Consulting Engineers, Landsvirkjun, Iceland]
One of Iceland‘s key energy sources, geothermal energy, provides the country with more than 25% of its total electrical energy supply and nearly all of its heating supply. The country‘s latest installation is the 90 MW Theistareykir geothermal power station in Northeast Iceland, owned and operated by the National Power Company, Landsvirkjun. The station has been in full operation since 2018. During its design, preparation and construction the unique nature of the Theistareykir area was taken into consideration and emphasis placed on environmental matters. Additionally, the preparation stage of the project was successfully assessed under the Geothermal Sustainability Assessment Protocol. The goal of this study was to assess environmental impacts associated with electricity generation in Landsvirkjun’s geothermal power plants. The assessment is part of a larger project which aims to assess the environmental impact of Landsvirkjun’s electricity generation via hydropower, wind and geothermal power. Although geothermal energy is a renewable resource it is not without impacts to its environment. One of the preferred methods to assess environmental impacts from a life cycle perspective is Life Cycle Assessment (LCA). The LCA for Theistareykir power station follows the international standards: ISO 14040, ISO 14044, EN 15804, and product category rules according to ISO 14025 for the preparation of Environmental Product Declaration (EPD) for electricity generation and distribution. The assessment provides numerical results on a variety of environmental impacts throughout the life cycle of the power plant, including the manufacturing of all construction materials and equipment, construction work, operation and end of life. According to the LCA results, the largest contributors to environmental impacts are direct emissions during the operation of the station during its lifetime, the manufacturing of all station components and fuel use during construction. The carbon footprint of electricity generation at Theistareykir is 13.8 g CO2-eq per kWh leaving the station, and 14.7 g CO2-eq per kWh when electricity transmission has been included. This is a relatively small carbon footprint compared to other geothermal projects. The carbon footprint is dominated by direct CO2 emissions from the geothermal fluid during the 40-year lifetime, amounting to 10.2 g CO2-eq/kWh or 69%, while the manufacturing and construction of station buildings, infrastructure and machinery accounts for 17% of the carbon footprint. The most carbon intensive units are the wells, in total constituting 8.2% of the carbon footprint. Direct hydrogen sulphide (H2S) emissions at Theistareykir is the main contributor to the impact category acidification, and an important contributor after applying weighting and normalisation. The results identify many opportunities for improvement of future development projects and for the operational years ahead, including measures to reduce CO2 and H2S emissions from the geothermal fluid, improving the station’s capacity and/or extending its lifetime with good maintenance. Although there is uncertainty regarding the number of make-up wells needed during the station’s lifetime, this LCA identifies opportunities to reduce their environmental impacts. The results of this assessment provide valuable information for the company in its plan to become carbon neutral by 2025, identifying environmental hot spots and highlighting where the largest improvements can be made in terms of eco-design of future projects, environmental impacts from the operational and end-of-life phases and to support sustainable procurement procedures. The results can be compared to LCA results of electricity generation via other energy sources and they form a basis for communication or marketing of results, e.g. using a standardized form such as an EPD.
|        Topic: Sustainability and Climate Change||Paper Number: 05024|