Análise técnico-económica e ambiental de alternativas de uso de hidrogênio verde para o acréscimo da produção de metano em sistemas de biodigestão

Abstract

In the pursuit of sustainable energy solutions, the transition to a low-carbon economy has become a central objective for countries worldwide. This work presents a comprehensive technical, economic, and environmental analysis of the use of green hydrogen to enhance methane production in biodigestion systems. Situated within the broader context of renewable energy adoption and the drive for decarbonization, with a particular focus on Brazil's energy matrix, which already incorporates a significant share of renewable sources. The rationale behind this research is anchored in the critical role that biogas, especially methane, plays in the renewable energy landscape. Biogas production from agricultural waste not only provides a pathway for waste valorization but also contributes to energy security and environmental sustainability. However, the methane yield from conventional biodigestion processes often fails to reach the expected potential. The introduction of green hydrogen into biodigestion systems emerges as an innovative strategy to overcome this limitation, promising to enhance methane production and enrich the energy value of biogas. The primary objective of this dissertation was to explore the feasibility and sustainability of integrating green hydrogen into biodigestion processes for methane enrichment. This objective was pursued through the evaluation of eight alternative pathways incorporating Power to Gas (P2G) technology, focusing on their technical performance, economic viability, and environmental impacts. The study specifically aimed to optimize biogas production from swine residues and elephant grass, considering their abundance and energy potential. Adopting a methodological framework that combines theoretical analysis with simulation tools, the research utilized Life Cycle Assessment (LCA) and SimaPro® software to systematically assess the environmental footprint of each proposed alternative. Economic analysis was based on production cost estimates, potential revenues, and overall economic viability. Technical evaluation focused on the efficiency of hydrogen integration into the biodigestion process and its impact on methane yield. 7 The results of this research revealed promising prospects for improving methane production through the synergistic use of green hydrogen. The explored alternatives demonstrated varying degrees of effectiveness in increasing methane content, with specific pathways showing significant potential for the sustainable upgrading of biogas. In scenarios where co-digestion was employed, higher energy results were obtained due to the use of grass silage, increasing biogas yield to 121.54 m³/ton. However, the economic analysis yielded less favorable results due to transportation costs and the quantity of hydrogen used. Economic analysis underscored the importance of supportive policies and technological advancements in improving the cost-effectiveness of these solutions. In conclusion, this dissertation posits that the integration of green hydrogen into biodigestion systems represents a viable and innovative approach to increasing methane production. This strategy not only aligns with environmental sustainability goals but also has the potential to strengthen the contribution of the renewable energy sector to the energy matrix. The implications of the study extend beyond technical and economic realms, highlighting the role of policy frameworks, market mechanisms, and research and development in facilitating the adoption of green hydrogen technologies. Looking to the future, the research identifies several avenues for future investigations, including exploring further.