H100 Consequences

Recent studies have concluded that supplying hydrogen to homes in place of natural gas may offer a cost-effective route to decarbonising heat. However the risks of using hydrogen in homes is not well understood.

SGN commissioned Kiwa as part of their H100 programme to experimentally simulate leaks of hydrogen and compare these with equivalent leaks of natural gas. Our task was to look at the impact of the ignitions of both hydrogen and natural gas and compare the two.

Experience of the effect of explosions of natural gas has built up over the last fifty years, and indeed there is evidence that natural gas explosions, however rare, damage property significantly. However this evidence is largely empirical, and there is a lack of scientific experiments comparing hydrogen and natural gas. Kiwa was tasked with addressing this knowledge gap, which will help gas distribution network operators with quantitative risk assessments to manage the risk involved in supplying hydrogen for domestic use.

Our approach

In theory modelling could be done to understand the impact of gas explosions in domestic dwellings. However in practice it’s difficult to achieve a reasonable degree of accuracy due to the complex set of variables involved, so it’s more practical to conduct actual experiments. Conducting a wide range of explosions in real houses is prohibitively expensive so Kiwa identified a meaningful alternative.

As a substitute for houses, Kiwa create a set of modified shipping containers to have the characteristics of homes such as air tightness, and also rooms, doors, windows, floors, kitchen appliances, etc.

Our consultants simulated a range of leaks inside a room within the containers, and measured the associated build-up of gas. This came with its own challenges, as for obvious safety reasons gas must be both injected and sampled from a safe distance (in this case around 100m). Similarly, the spark that caused the controlled explosions must also be managed from the same safe distance, as well as the effects of the explosion measured.

Accurate gas analysis, high-speed video recording and high-speed pressure measurements also required the careful selection and use of sensitive equipment.

Apart from tackling the knowledge gap and assessing the impact, the project extended to gathering information about the effect of house fire on the integrity of gas fittings, analysing the function of gas detectors and the impact of explosions in appliances such as boilers, cookers and fires.

The outcome of the project is detailed in the report, which will be accessed from here as soon it has been approved for public release.

• Devised and specified the methodology
• Designed, specified and procured the test facilities and equipment
• Designed the experimental programme
• Conducted the explosion test work with our commercial partners
• Conducted the data analytics
• Wrote the project report and made recommendations