Detailed and simplified parameterized LCA models for early-stage energy projects: A microalgae-based biogas case

Developing renewable energy projects is a key strategy to reduce environmental impacts in the energy sector. Initial phases of the implementation of such kinds of projects include feasibility studies, conceptual design, and design development and permitting, with environmental considerations being crucial. This paper proposes detailed and simplified Life Cycle Assessment (LCA) models to support project developers. The study focuses on three specific environmental impact categories: abiotic depletion potential of fossil fuels (ADP:FF) and minerals/metals (ADP:MM) and climate change. These categories were selected to ease explanation and their direct relationship with system inputs and outputs facilitate the improvement of overall performance. Detailed models help project developers with the support of LCA experts identify processes contributing the most to environmental impacts, facilitating improvements during conceptual design, and design development and permitting. Simplified models can be directly and easily used by project developers to analyze environmental compliance of project options during feasibility studies. A detailed model uses parameters to describe system inputs and outputs, which is then simplified through Global Sensitivity Analysis to reduce the number of these parameters. In this paper, the proposed approach is applied to a microalgae-based biogas production system. Our detailed model uses 39 parameters, identifying materials and energy flows contributing to environmental impacts. Main contributors are enzymes production for pretreatment and CO2 production for cultivation. The simplified models generated in this paper ease early estimation of environmental performance thanks to the use of less than 19 parameters instead of 39, reducing data collection time.