Shelley Brace
Keele University
Shelley Brace is a post-doctoral researcher at Keele University studying the effects of hydrogen gas on materials that are exposed to the gas network. Prior to this project Shelley completed a post-doctoral role, designing and engineering a gas enrichment rig for the purpose of 17O gas enriching zeolite materials. Shelley also completed a PhD at Keele University synthesising and characterising novel inorganic materials.
Introduction: The UK government has committed to an ambitious target of an 80 % reduction in CO2 emissions by 2050 (from 1990 levels). As the provision of heat makes up almost 50% of UK energy consumption mainly provided by gas, the decarbonisation of heat is a key requirement in meeting the CO2 emissions targets.
The inclusion of injected hydrogen up to 20% v/v presents a potential route to decarbonise the gas system whereby previous studies have shown that existing appliances can operate safely at this level of hydrogen. In preparation for a 1-year live trial on Keele University’s gas network, this project investigates the likelihood of adverse affects on gas network materials.
Method: In order to determine whether adverse affects on network materials are likely to occur within or after the trial of up to 20% hydrogen addition, various materials identified within the gas network have been soaked in 100% hydrogen gas for up to 9 weeks. Stainless steel, copper, and brass, powders and specimens have been subsequently studied by thermal desorption to determine their hydrogen gas susceptibility.
R&D: Grade 304 stainless steel powder was soaked in 100% hydrogen gas for up to 9 weeks. Due to the increased surface area of powdered materials compared to specimens, it is possible to determine longer term hydrogen gas susceptibility from a short term study. Despite being generally understood that steel suffers from hydrogen embrittlement, the 9 weeks hydrogen gas soaking showed no hydrogen gas susceptibility (Figure 1). This result was also found for copper powder (Figure 2).
Stainless steel rod however is closer to the network conditions and indicated a small increase in hydrogen desorption for longer hydrogen gas soaking times. It is unclear if this is sufficient to affect the mechanical performance of 304 steel.
The hydrogen gas susceptibility of brass (70/30) powder soaked in 100% hydrogen gas for up to 9 weeks (Figure 3) shows a trend of increasing hydrogen gas desorption for longer soaking times. This effect is also exaggerated at higher temperatures (not shown) and will be taken into account within the parameters of the trial.
