SUSTAINABLE ENERGY-WATER-FOOD NEXUS INTEGRATION AND OPTIMIZATION IN ECO-INDUSTRIAL PARKS

Abstract

As the global population increases and economies expand, demand for energy, water, and food resources increase accordingly and thus require effective resource management. These resources are interdependent and are connected using sub systems that represent technologies within a defined energy, water, and food nexus system. Emphasis on the inherent interlinkages between the resources as promoted by the energy, water, and food nexus approach can support efficient resource utilization. In this study, a superstructure of the Energy-Water-Food (EWF) nexus is generated to capture the trade-offs and synergies among sustainability aspect within an industrial park. A distinctive systems approach based on thermodynamics is developed to optimize the nexus and improve resource efficiency. The illustrative case study contains of different processes operating in the State of Qatar including various chemical plants. The case study is simulated using the “what’s Best” Mixed-Integer Global Solver and assessed to determine resource efficiency enhancements across various scenarios and considers multiple objectives to capture the trade-offs between minimum total annual cost and environmental emissions. Significant emphasis is placed on capturing the synergy capabilities from utilizing biomass from the food sector. The global warming potential (GWP) in the best scenario decreases by almost 30 % while the exergy efficiency of the system is enhanced by 28 %. A sustainability metric is applied to compute the effect of each scenario on EWF resources and support the decision makers. Furthermore, this study aims to design a systematic approach to study the integration of the EWF nexus within eco-industrial parks, uniquely focusing on the combination of the EWF nexus and carbon capture/utilization processes. The proposed nexus network superstructure is applied to an industrial park consisting of several chemical processes, including desalination, wastewater treatment, representative food processes, biomass gasification, waste heat recovery, and carbon capture units. The outcomes determine that the biomass and carbon capture utilization scenarios are the most significant, which improve the emissions by 11 % and 40 %, respectively, while there was no significant change in the scenario of wastewater treatment and reuse. The total cost of the optimum solution after biomass utilization is almost the same compared to the base scenario. Furthermore, the waste heat utilization scenario can potentially reduce a corresponding GWP amount of almost 1.55×104 Mt CO2-eq/yr for more efficient resource management. Moreover, an EWFC nexus system is integrated with a greenhouse system and is solved to obtain the optimal solution and minimize the total annual cost further to the environmental evaluation. The optimum solution reduces the total annualized cost by 1 % while the GWP decreases by 37%. Renewable integrated EWF nexus systems (solar and biomass) are further studied using thermodynamic analysis of the system. The objective is to study the dependence of the energy-water-food nexus performance over the solar capacity and to capture the trade-offs among different resources. The key components of the integrated system include solar thermal collectors, Rankine cycle, reverse osmosis desalination unit, food/agriculture unit, a biomass gasification process, and ammonia and urea production units. A comprehensive thermodynamic model and energy and exergy balances are used to evaluate the performance of the proposed system. Furthermore, the effects of different parameters on the system efficiencies are investigated. The overall energy and exergy efficiencies of the proposed system are 45.77% and 18.92%, respectively. The outcomes demonstrate that by using the solar collectors, the system is able to produce almost 78 MW electricity, 28 kg/s freshwater, and 7 kg/s ammonia/urea fertilizer for agricultural purposes.

Date of Award	2023
Original language	American English
Awarding Institution	HBKU College of Science and Engineering