Energy, exergy and optimization of a binary hydrogen-power production system with net zero emissions
Year: 2024
Type: article
Abstract: This paper presents a study of a proposed system that concurrently generates electricity and hydrogen with zero net carbon emissions from natural gas, water and renewable energy. The system couples a Net Zero Cycle (NZC) oxy-combustion power plant to a hydrogen electrolyzer powered by renewable energy. The underlying principle for the synergy of this coupling is based on the electrolyzer providing the necessary oxygen for the NZC combustion process. This arrangement facilitates the elimination of a coupled Air Separation Unit (ASU) from the NZC. To model this hydrogen-power system, the process simulator Aspen Plus was utilized to model the NZC while the hydrogen production was modelled using both Aspen Custom Modeler and Aspen Plus. The linked system was studied in detail to understand its behavior. Comprehensive sensitivity analyses clarified the main factors affecting the system's performance and the effect of extent of oxygen supply to the NZC. The operating conditions of the coupled processes were optimized using the Particle Swarm Optimization (PSO) technique, integrated with the Latin Hypercube Sampling (LHS) method. This was followed by an exergy analysis to identify and quantify the exergy dissipation within the system.In the linked process, the energy consumption of turbomachinery in NZC increases by 16.86% due to the need for compressing electrolyzer-produced oxygen to combustion levels. Nevertheless, the net power output of NZC increases by 16.99%, mainly due to the elimination of the energy-intensive ASU, increased heat provision by the electrolyzer to the regenerator, and the combustion of hydrogen mixed with the oxygen output. Consequently, NZC's efficiency improves from 53.65% to 62.77% with this integration. The research also points out the electrolyzer's efficient use of condensed water from the NZC process without the risk of salt precipitation. Sensitivity analyses revealed that the system's performance is predominantly influenced by the electrolyzer's recirculation molar flow, combustion outlet temperature (COT), turbine outlet pressure (TOP), and combustor outlet pressure (COP), with by factors of 1.92%, 1.45%, 0.8%, and 0.71%. The hydrogen-power system achieves a maximum efficiency of 68.14%. The research also identifies the electrolyzer as the primary source of exergy loss, followed by the combustor.
Source: Fuel
Institution: Monash University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,200
OpenAlex ID: W4404073004