An Integrated Life Cycle Assessment Framework for Power-To-X Applications in Water Systems

Wastewater treatment systems are essential for the protection of the human environment. Recently, there has been a significant increase in the demand for hydrogen as an energy carrier and for renewable energy sources. This study presents a framework for assessing the environmental impact of integrating Power-to-X (PtX) technologies with water treatment systems. Building on the foundation established by Liu et al. in their recent work [1], this research explores one of the possible sustainable water sourcing, utilization of hydrogen as a product, and oxygen as a by-product, in water resource recovery facilities (WRRFs). The study conducts a comparative analysis between a conventional Water Resource Recovery Facility (WRRF) modeled on the BSM2 framework and a modified facility integrated with an electrolyzer powered by surplus energy from wind turbines. The modified approach aims to produce hydrogen by electrolysis, reacting it with carbon dioxide from biogas (which constitutes 40% of the volume of biogas in a conventional model) to increase the methane concentration to 99 percent. This integration also aims to use the oxygen generated in the electrolysis process within the aeration lines, reducing the energy required for aeration by 41%. This study is built on the assumption that if 3 to 5 percent of the electricity generated by wind turbines in Denmark is surplus and not consumed due to lower market demand, it can be harnessed by electrolysers to produce materials that improve the sustainability of water treatment facilities. Our findings reveal that while the electrolyzer’s electricity consumption is substantially higher, approximately 94 percent more than that used in traditional water treatment processes, the integration of PtX technologies yields significant environmental benefits. Specifically, although midpoint environmental impact assessments indicate increased potential effects on human health, the endpoint analysis demonstrates profound positive outcomes. This suggests that initial environmental costs are offset by substantial long-term benefits, which underscores the effectiveness of integrating PtX technologies in improving the sustainability of water resource recovery facilities. However, these findings highlight the need for future studies to go deeper into the details of the process. Further investigation is crucial to fully understand the operational intricacies, optimize technology integration, and evaluate the long-term environmental and economic impacts of implementing PtX technologies in water resource recovery facilities.