This report is developed as a part of the project “EMSA study investigating the safety of hydrogen as fuel on ships”. The overall objective of the project is to carry out a structured set of safety assessments and reliability analyses,delivering a Guidance document addressing ships using hydrogen as fuel. The purpose is to assist the industry and the regulators towards a safe and harmonised deployment of this relevant technology that could demonstrate an important step towards decarbonisation of the sector.

The testing provided data to allow the ability of Computational Fluid Dynamics (CFD) modelling to predict accumulation of natural gas from transient releases and temporal and spatial variations in explosion loading. Strain and pressure data was also gained on the structural response to allow assessment of structural modelling. 

Mixing of hydrogen into natural gas, as a means of mitigating environmental concerns associated with the use of fossil fuels, poses a question of performance of appliances designed for use with natural gas, when fuelled by blends of hydrogen and natural gas. This study examines the performance of space and water heating appliances fuelled by methane as a natural gas proxy, and methane/hydrogen blends containing up to 15% hydrogen.

Hydrogen Safety Panel, Safety Knowledge Tools, and First Responder Training Resources 

Hydrogen Safety Panel, Safety Knowledge Tools, and First Responder Training Resources 

The ignition of a hydrogen-air mixture that has engulfed a typical set of ambient vaporizers (i.e., an array of finned tubes) may result in a deflagration-to-detonation transition (DDT). Simplified curve-based vapor cloud explosion (VCE) blast load prediction methods, such as the Baker-Strehlow-Tang (BST) method, would predict a DDT given that typical ambient vaporizerswould be rated as medium or high congestion and hydrogen is a high reactivity fuel (i.e., high laminar burning velocity).

VIII.6  Hydrogen Safety Panel, Safety Knowledge Tools and First Responder Training Resources

Ammonia and hydrogen represent opposite ends of the spectrum with regard to the potential blast loading resulting from an accidental vapor cloud explosion (VCE), although many in industry have expressed doubts as to whether either of these fuels actually pose a VCE hazard. Ammonia is some-times discounted as a VCE hazard due to the perceived difficulty in igniting an ammonia-air mixture and/or because of its low laminar burning velocity. Hydrogen is sometimes discounted as a VCE hazard due to the ease with which a hydrogen-air mixture can be ignited and/or because of its buoy-ancy.

VIII.6  Hydrogen Safety Panel, Safety Knowledge Tools and First Responder Training Resources

The aim of the present work is to assess the risk of explosion in closed containments used for the transportation of nuclear materials or nuclear waste. Indeed, it is very well known that hydrogen can be produced due to (i) the radiolysis of different materials within the containment, (ii) the thermal decomposition of mainly the organic part in the containment. Since hydrogen has a very low ignition energy and a very wide flammability domain, it is important to determine the risk of ignition of the subsequent mixture produced by the aforementioned mechanisms.