Life cycle assessment of enhanced geothermal systems with CO2 as a working fluid—polish case study

Abstract Life-cycle assessment (LCA) is a methodology used to quantify the sustainability of a product, system, or process over its lifetime. The approach allows us to determine energy and material consumption at all life cycle stages, from raw material extraction to the end of a product's life, including the design, production, operation, and end-of-life stages. The LCA aims to assess the overall environmental impact of a facility, consider its strengths and weaknesses, and identify possible solutions to reduce the environmental burden sustainably. This research focuses on a novel approach to using carbon dioxide (CO 2 ) as a working medium. The following research combines two key aspects of electricity production and carbon dioxide sequestration, a solution that can contribute to producing clean energy and reducing CO 2 in the atmosphere. This paper aimed to assess the impact of enhanced geothermal systems (EGS) through a life-cycle analysis carried out under Polish conditions for the Gorzow block. It includes differentiating the main impact categories and key system components that indicate the most vulnerable areas. A framework available in the literature and the modelling results performed within the EnerGizerS project were adapted to carry out the study. Calculations were performed using SimaPro software. The work was performed for EGS with supercritical CO 2 (sCO 2 -EGS) as the working fluid in a configuration involving direct expansion in a turbine for electricity production. An environmental impact assessment was conducted, including estimating the carbon footprint for such an installation and different working fluid mass flows. The main objective of the environmental analysis is to examine how the project will affect the various environmental elements (air, water, soil) or forms of nature conservation and to identify ways to prevent, reduce or minimise the effects of the planned investment. The study results show that the construction phase, which includes well drilling and hydraulic fracturing, has the most significant impact on the environment with climate change values for different working fluid mass flows. This phase dominates the indicators obtained, which are considered typical for renewable energy sources. Graphical Abstract