Exergy hub based modelling and performance evaluation of integrated energy system

Abstract

Efficient energy deployment, fossil fuel sources reduction and Intermittent Renewable Energy Sources (IRES) integration has become a core goal of power system operators to attain sustainable and environmentally benign energy system. In such context, Integrated Energy System (IES) is a promising solution to improve system performance by coupling various energy carriers in an energy hub to fulfill diverse consumers’ energy needs. However, the widely used criteria for energy system modelling is based on energy analysis that considers energy quantity only and neglects energy quality. Consequently, exergy index computation becomes a vital issue that accounts energy quantity along with energy quality to provide an accurate assessment. Hence, this paper proposes an exergy hub approach to model IES that constitutes electricity, District Heating (DH) and Individual Heating (IH) infrastructure of China for the year 2020. At first, the exergy efficiency of energy-producing components is calculated by using Cycle-Tempo and Engineering Equation Solver (EES). Then, IES performance is evaluated by computing annual costs, Primary Energy Supply (PES), CO2 emissions and renewable energy share with the help of EnergyPLAN technical simulation strategy. These aforementioned performance indicators are investigated for three different cases like IRES maximum integration in electricity infrastructure (Case 1), Heat Pump (HP) inclusion in IH infrastructure (Case 2) and Thermal Storage (TS) addition in DH infrastructure (Case 3) and these cases comparison with energy hub results are also provided. Energy and exergy hub approaches substantiate different results as IRES integration proves the most cost-efficient and decarbonized alternative in exergy hub while in energy hub TS addition is the best case alternative. Though IRES integration deemed cost-efficient with reduced emissions in exergy hub but in comparison to energy hub, this case is costly as exergy efficiency of IRES are lower than energy efficiency. Similarly, HP and TS exergetic results are inferior to energetic because high quality energy is being exploited to produce low quality energy and heat producing components are less exergetically efficient.