Hierarchical energy management for heterogeneous multi-energy microgrid community: Integrating hydrogen into the water-energy nexus

The global shift towards green hydrogen production increases the interdependency on the water sector. To facilitate this transition, this study proposes a novel multi-energy microgrid (MEMG) community model, where a coastal MEMG leverages seawater resources to support hydrogen production in interconnected hydrogen-based MEMGs. To this end, a three-step hierarchical energy management framework is developed to realize the water and electric energy transactions among them. The first two steps involve information sharing and local-level optimization while the final step includes the energy trading decision and surplus energy allocation. To ensure fairness in the community, the proportional energy allocation technique is used, with fairness measured using Jain’s fairness index. A mixed integer linear programming model is developed to reduce community costs and emissions, and a bi-variate piecewise McCormick envelope technique is proposed to deal with model non-linearities. The computational efficiency, as well as the economic and environmental impact of the proposed model, is evaluated through various case studies. The results indicate that the proposed framework achieves a 32.3 % cost reduction and a 20.7 % emissions reduction through multi-energy trading. Furthermore, the contribution of electric and water trading alone within the community in cost reduction is 16.73 % and 22.45 %. The proposed method ensures maximum fairness in surplus energy distribution, with a Jain’s fairness index value of 1. In addition, the computational comparison with a centralized strategy shows a considerable reduction in processing time, averaging 669.5 s. Sensitivity analysis further validates the model’s applicability, particularly in assessing the cost and emissions contributions of water in hydrogen production.