Design and evaluation of integrated energy systems under component failures for balancing reliability, costs, and greenhouse gas emissions

The design of integrated energy systems (IESs) often targets N -1 reliability, i.e., the ability to prevent undersupply despite the failure of any single component. Achieving N -1 reliability requires the installation of redundant or oversized components, which increases costs and greenhouse gas (GHG) emissions. To navigate design trade-offs, multi-objective design optimization has been proposed. However, the accuracy of reliability metrics in design optimization is limited, especially for IESs with energy storage. Inaccurate reliability metrics can misguide IES planners, leading to insufficient reliability or unnecessarily high costs and GHG emissions. To ensure accurate reliability metrics, we propose the BRACE method, which combines multi-objective design optimization with Monte Carlo-based design evaluation. BRACE’s novelty is the consideration of component failures and the storage contribution to reliability during design optimization and evaluation. Additionally, BRACE integrates a novel variant of the N -1 reliability approach that improves upon state-of-the-art variants by optimizing storage reserves and considering the transition between failure-free and N -1 operation. Applied to two case studies, BRACE reveals significant trade-offs between reliability, costs, and GHG emissions. Design evaluation shows that compromise designs can achieve sufficient reliability if minor undersupply events are acceptable. The novel N -1 variant reduces the total objective value of generated designs by up to 1.3 % compared to existing variants. Furthermore, it extends the applicability of the N -1 approach to IESs that require storage reserves to bridge failures. Altogether, BRACE supports the reliable design of energy systems with storages.