Power/thermal-to-hydrogen energy storage applied to natural-gas distributed energy system in different climate regions of China

Abstract

This paper presents a novel distributed energy system (DES) with hybrid-hydrogen energy storage, in which the proton exchange membrane electrolyzer (PEMEC) and steam reforming of methanol (SRM) are used to convert surplus power and waste heat into hydrogen. To identify the feasibility of the proposed DES in different climate regions, a case study is performed to choose a rehabilitation hospital in Harbin, Jinan, Wuhan and Guangzhou of China to explore the DES optimal configurations. The mixed integer linear programming model is established and the multi-objective optimization considering annual total cost (ATC) and annual carbon emissions (ACE) is conducted by improved version of augmented ε-constraint (AUGMECON2) method for system optimal configurations. After selecting four cases among Pareto frontiers for each city, the two methods of Analytic Hierarchy Process/Shannon entropy combined with Gray Relation Analysis are performed to determine the most suitable locations. The results show that adding the SRM to DES as a hybrid-hydrogen energy storage system can improve the configuration flexibility, environmental performance and primary energy ratio compared with only-electrochemical hydrogen storage DES. The Pareto frontiers for four cities demonstrate a trade-off between ATC and ACE, and the ACE is decreased by 6.3% with ATC increased by 1.4% in Jinan. Generally, Guangzhou is the best suitable city, and Jinan and Wuhan rank second by two evaluation methods with 0.727 and 0.643 average scores, respectively. The current electricity and natural-gas prices are verified to be beneficial to Jinan to deploy the proposed DES, and Guangzhou and Wuhan present a better economic performance with the minimum ATC decreased by 11.4% and 6.58% under ideal energy prices. The results can provide useful information for hybrid-hydrogen energy storage application to DES in different climate regions.