Energy storage for large scale/utility renewable energy system - An enhanced safety model and risk assessment

Abstract

Renewables recorded 26.2% of global electricity generation in 2018 and expected to rise to 45% by 2040 attributed to nations commitment to reduce greenhouse gases since the signing of Paris agreement 2015. Policies friendly towards the development of renewable energy sources are developed, but the risk and safety assessment are still based on the traditional analytic and probabilistic risk-based assessment practices such as Event Tree Analysis (ETA), Fault Tree Analysis (FTA), Failure Mode Effect Analysis (FMEA), Hazards Identification (HAZID), Hazards and Operability (HAZOP). These practices are viewed as own envelop of methodology whilst sharing a lot of common parameters and working principles. Analytic approach is becoming ineffective with increasingly complex energy system integrating renewables. There are on-going research proposing systemic based risk assessment approach but without incorporating advantages from analytic approach. The aim of this paper is to provide a comprehensive analysis of risk and safety assessment methodology for large scale energy storage currently practices in safety engineering today and comparing Causal Analysis based on System-Theoretic Accident Model and Process (STAMP) and Systems-Theoretic Process Analysis (STPA) with fault tree analysis, FMEA, HAZID, HAZOP. This paper demonstrated that systemic based risk assessment such Systems Theoretic Process Analysis (STPA) is suitable for complicated energy storage system but argues that element of probabilistic risk-based assessment needs to be incorporated. This is to ensure holistic risk assessment is performed to energy storage system and provide a new viewpoint for underlying safety model in integrated manner based on performance requirements, human factor, environmental, management, safety, and legislation. The results describe the improvement of risk assessment technique via Systems Theoretic Process Analysis-Hybrid (STPA-H) using a case study of grid connected Photovoltaic (PV) system with Li-ion battery storage. The hazards and mitigation measures identified from STPA-H are presented and compared with existing approach. STPA-H technique proposed is applicable for different types of energy storage for large scale and utility safety and risk assessment. This paper is expected to benefit Malaysian government with the progression of Large-Scale Solar 3 (LSS3) and serve as reference to future energy system risk assessment.