*2.1. Life Cycle Assessment*

The environmental assessment of this study was made using a life cycle assessment (LCA). Life cycle is comprised by the materials extraction, whole supply chain of materials and energies, production process of the specific product, utilization, and end of life. Therefore, the LCA method is considered as a "cradle to grave" analysis. The LCA method consists of the following four steps, defined by the ISO 14,040 standards [11]: goal and scope definition, inventory analysis, life cycle impact assessment, and interpretation.

#### 2.1.1. Goal and Scope Definition

This step outlines the depth of the study by defining the assessed scenarios, their system boundaries, and functional unit. This study aims to assess and compare the environmental impacts of CO2 capture of two scenarios:


The functional unit (FU) definition provides a reference to which all inputs and outputs of the system are calculated. Thus, FU allows the comparison between the different systems. In this study, FU is defined as 1 kWh of produced electricity, the usual definition of FU for energy systems. The system boundaries describe the processes and modules of the assessed systems included (and excluded) in the environmental model.
