Exploiting outcomes of life cycle costing to conduct coherent screening social life cycle assessments of emerging systems: a case study of microalgae biorefineries
Authors: Pérez-López Paula , Rajaonison Andriamahefasoa , Zebian Bashar , Bouallou Chakib , González-Fernández Cristina , Greses Silvia , Gómez-Serrano Cintia , Acién Fernández Francisco Gabriel 
Published: January 2025

Abstract

Purpose
Microalgae are considered a promising source of bioenergy and high value-added products that could help face the rising demand for energy and raw materials. However, microalgae systems entail consumption of materials and energy, with potential environmental, economic, and social costs. While environmental and economic impacts have been analyzed in the literature, the social dimension has been barely explored. In this article, social life cycle assessment (S-LCA) is applied to identify the main contributors to social risks.

Methodology
In this paper, an approach is proposed and applied to exploit outcomes of a Life Cycle Costing (LCC) study as the input data to model and evaluate the potential social impacts of microalgae biorefinery schemes. Such approach helps ensure the consistency between the economic and social assessments, while facilitating data gathering in a context of data scarcity typical of an emerging technology. Priority levels for stakeholder categories and impact subcategories have been assigned based on the literature. Workers and local communities were identified as the stakeholders with the highest priority, related to impact subcategories such as health and safety issues and fair salary for the former and local employment for the latter. An inventory model was built, using PSILCA database v2.0 Starter and openLCA software, together with cost estimates from an LCC using real data from experiments at lab and pilot scale.

Results
According to the results, the main contribution to social risks of the biogas production is expected to be linked to the anaerobic digestion. Some contributors, both from the cultivation and the anaerobic digestion, are basic chemicals production and market public sewage activities, together with civil engineering and construction, and metal products and machinery production. The geographical distribution of risks depends on the stakeholder category and impact subcategory. Since many activities of the value chain are assumed to happen in Spain, a non-negligible part of social risks take place there. However, other countries with minor contributions to total working time are found to have the highest social risk for subcategories and indicators such as fatal accidents. Finally, three scenarios have been compared, considering production in a Chinese, French, or Spanish context, which lead to significant differences.

Conclusions
This study aims to highlight the importance of assessing the different dimensions of sustainability in a coherent manner. Furthermore, it provides useful information and hints on main contributors to potential social impacts in the microalgae-based sector based on available information and generic S-LCA databases, and their dependence on geographical locations of the life cycle activities. Despite limitations, conducting such social assessments with available tools is key to better understand the need for widening the scope of sustainability studies.