Industrial symbiosis (IS) involves transferring waste materials and/or energy flows between stakeholders to enhance resource efficiency and reduce environmental impacts. The success of these transactions depends on supply–demand matching, technical feasibility of waste integration into industrial processes, economic savings, and compliance with legal and environmental regulations. This paper presents a methodology for the technoeconomic assessment of IS projects, integrating material flow cost accounting (MFCA) and cost–benefit analysis (CBA) incorporating CAPEX and OPEX considerations. MFCA, traditionally used to identify hidden costs from inefficiencies, is adapted here to assess resource utilisation across industry networks. The methodology is applied to two real-world demo cases: a novel fertiliser production process in Escombreras (Spain), where IS focuses on process optimisation and by-product valorisation, and an IS process design in Frövi (Sweden), where CO₂ and residual energy flows are exchanged between industrial sectors. The results demonstrate the potential of MFCA-CBA integration to enhance decision making in IS implementation. In Spain, process optimisation led to a 50% reduction in operating costs, whereas, in Sweden, CO₂ reutilisation resulted in a 30% increase in resource efficiency. These findings highlight the economic and environmental benefits of IS and provide insights into cost allocation and pricing strategies.

This work is focused on presenting the main results and discussions concerning the environmental benefits of reducing the non-condensable gases emitted from the Nesjavellir geothermal power plant. The primary objective of this study is to conduct a life cycle evaluation to analyse the overall environmental benefit effects of producing 1 kWh of electricity and 1 kWh of thermal energy in the geothermal power plant at Nesjavellir, which is located in Iceland. The assessment is performed both before and after implementing an abatement system designed to reduce CO₂ and H₂S gases. The production of geothermal energy is increasing every year and, therefore, it is crucial to identify and quantify the key environmental factors of producing this type of energy and improvements for the future energy transition of the energy generation sector. Firstly, the results show that the environmental impact of electricity production is higher compared to heat production. More in detail, the emissions due to the nature of the geothermal fluid and the construction phase represent the most relevant environmental load for both electricity and heat production for nearly all the 18 environmental impact indicators studied. Furthermore, considering the abatement system for the non-condensable gas emissions, reductions of 78% and 60% in global warming potential is achieved for a production of 1 kWh of electricity and 1 kWh of thermal energy. In terms of external environmental costs, the implementation of an abatement system results in a reduction exceeding 95% for both electricity and thermal energy production per kilowatt-hour. The outcomes obtained from both the baseline scenario and the application of the abatement system undeniably prove that the latter results in a substantial decrease in the overall environmental impacts linked to the generation of 1 kWh of electricity and 1 kWh of heat, encompassing a notable reduction in external environmental costs (externalities).

This study pioneers a combined Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) evaluation of an industrial symbiosis (IS) case involving waste heat recovery from a pulp and paper mill to a tomato greenhouse in Sweden. Unlike previous studies that assess environmental or economic aspects separately, this research provides a holistic assessment quantifying both environmental burdens and economic feasibility. A comparative analysis framework is applied, evaluating a symbiotic real case of waste heat recovery versus conventional greenhouse tomato production in the Netherlands and subsequent import to Sweden. LCA examines greenhouse gas emissions, eutrophication, toxicity, land use, and resource depletion, while LCC assesses total ownership costs, including Capital and Operational Expenditures. The findings demonstrate that the IS scenario significantly reduces greenhouse gas emissions and operational costs while enhancing energy efficiency. This work fills a gap in IS literature, offering a replicable framework for sustainable greenhouse operations. The results highlight the potential of IS to improve resource efficiency, promote circular economy strategies, and foster sustainable practices in the agri-food sector.

Industrial symbiosis (IS) plays a crucial role in enhancing sustainability within industrial ecosystems by facilitating the exchange of waste, by-products, energy, and resources among different industries. This collaborative approach reduces resource consumption, minimizes waste generation, lowers disposal costs, and creates economic opportunities through synergistic relationships. This study focuses on the production of potassium nitrate (KNO₃) in the Escombreras industrial area in Spain, employing life cycle assessment (LCA) and life cycle cost analysis (LCC) to evaluate the impact of IS strategies. The ReCiPe method, implemented through SimaPro software and supported by market data from the Ecoinvent 3.8 database, is used for a comparative analysis between conventional KNO₃ production and improved technologies that promote circular economy principles. The LCA and LCC methodologies provide a comprehensive evaluation of both environmental and economic performance, considering key factors influenced by IS synergies. Results demonstrate significant environmental and economic benefits from the integration of IS into KNO₃ production, revealing the potential for improved sustainability and competitiveness through circular economy practices. This research provides valuable insights into how IS can enhance both environmental performance and cost-efficiency in industrial processes. These findings support the integration of IS as a viable pathway toward sustainable and cost-effective fertilizer production.