Enabling Dry Low Emission Hydrogen Combustion in an Existing Combined Heat and Power Plant: A Preliminary Risk Assessment

This paper presents a Failure Modes, Effects and Criticality Analysis (FMECA) of a retrofitted dry low emission (DLE) hydrogen combustion technology in an existing gas turbine, potentially operable with natural gas/hydrogen mixtures up to 100 % hydrogen. The FMECA assessment is not limited to the gas turbine itself, it also involves a combined heat and power plant, currently designed for natural gas. Failure modes and their effects are identified and analyzed to define possible safety concerns associated with the retrofitted gas turbine and the connected systems and processes. Known and existing mitigation measures are also addressed, with the goal of identifying potential knowledge gaps and future research activities, referring to the "as low as reasonably practicable" (ALARP) principle. Aiming at a comprehensive representation of the most relevant scenarios in terms of failure probability, failure consequence and detectability, suitable mitigation strategies are identified. The analysis allows for the identification of additional data necessary for a complete quantitative risk assessment, supporting the implementation of dedicated risk mitigation strategies within the overall conversion process of heat and power plants.

Keywords: Hydrogen, Gas Turbine, Risk Assessment, Safety, FMECA, Risk Analysis, Combined Heat-Power.