Institution of Gas Engineers & Managers

This paper discusses the optimization of hybrid power systems which consist of solar cells wind turbines fuel cells hydrogen electrolysis chemical hydrogen generation and batteries. Because hybrid power systems have multiple energy sources and utilize different types of storage we first developed a general hybrid power model using the Matlab/SimPowerSystemTM and then tuned model parameters based on the experimental results. This model was subsequently applied to predict the responses of four different hybrid power systems for three typical loads without conducting individual experiments. Furthermore cost and reliability indexes were defined to evaluate system performance and to derive optimal system layouts. Finally the impacts of hydrogen costs on system optimization was discussed. In the future the developed method could be applied to design customized hybrid power systems.

The transition of Malaysia from fossil fuels to renewable energy sources provides significant challenges and opportunities for various energy sectors. Incorporation of H₂ in the primary energy mix requires a deal of complexity in its relation to production transportation and end-use. The Sarawak State Government in Malaysia implemented a hydrogen energy roadmap for the year 2005–2030 on the state-level but despite the great enthusiasm and full support given by the government the development of hydrogen technology is still far from its goals. This is due to several factors that hinder its progress including (1) inability of hydrogen to be integrated with current primary energy infrastructure (2) limited technology resources to produce sustainable hydrogen and (3) lack of technical expertise in the field of hydrogen. In this paper a potential national roadmap and milestones are presented based on the power-to-gas (P2G) approach combined with its implications on the national natural gas (NG) pipeline network. Besides that the long-term and short-term strategies and implementation mechanisms are discussed in detail. Furthermore complete research schemes are formulated to be inline with the presented vision to further enhance technology development and implementation.

With the development of high-altitude and long-endurance unmanned aerial vehicles (UAVs) optimization of the coordinated energy dispatch of UAVs’ energy management systems has become a key target in the research of electric UAVs. Several different energy management strategies are proposed herein for improving the overall efficiency and fuel economy of fuel cell/battery hybrid electric power systems (HEPS) of UAVs. A rule-based (RB) energy management strategy is designed as a baseline for comparison with other strategies. An energy management strategy (EMS) based on fuzzy logic (FL) for HEPS is presented. Compared with classical rule-based strategies the fuzzy logic control has better robustness to power fluctuations in the UAV. However the proposed FL strategy has an inherent defect: the optimization performances will be determined by the heuristic method and the past experiences of designers to a great extent rather than a specific cost function of the algorithm itself. Thus the paper puts forward an improved fuzzy logic-based strategy that uses particle swarm optimization (PSO) to track the optimal thresholds of membership functions and the equivalent hydrogen consumption minimization is considered as the objective function. Using a typical 30 min UAV mission profile all the proposed EMS were verified by simulations and rapid controller prototype (RCP) experiments. Comprehensive comparisons and analysis are presented by evaluating hydrogen consumption system efficiency and voltage bus stability. The results show that the PSO-FL algorithm can further improve fuel economy and achieve superior overall dynamic performance when controlling a UAV’s fuel-cell powertrain.

Pipeline failure caused by Hydrogen-Induced Cracking (HIC) also known as Hydrogen Embrittlement (HE) is a pressing issue for the oil and natural gas industry. Bursts in pipelines are devastating and extremely costly. The explosive force of a bursting pipe can inflict fatal injuries to workers while the combined loss of product and effort to repair are highly costly to producers. Further pipeline failures due to HIC have a long lasting impact on the surrounding environment. Safe use and operation of such pipelines depend on a good understanding of the underlying forces that cause HIC. Specifically a reliable way to predict the growth rate of hydrogen-induced cracks is needed to establish a safe duration of service for each length of pipeline. Pipes that have exceeded or are near the end of their service life can then be retired before the risk of HIC-related failures becomes too high. However little is known about the mechanisms that drive HIC. To date no model has been put forth that accurately predicts the growth rate of fractures due to HIC under extreme pressures such as in the context of natural gas and petroleum pipelines. Herein a mathematical model for the growth of fractures by HIC under extreme pressures is presented. This model is derived from first principles and the results are compared with other models. The implications of these findings are discussed and a description of future work based on these findings is presented.

Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och-Function [1] was fitted on the measured cyclic lifetimes.<br/><br/>The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increased by approximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 environment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes compared to ambient test results. The investigation of the crack surfaces showed distinct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change.

Stress corrosion cracking (SCC) of metals is an issue of major concern in engineering since this phenomenon causes many catastrophic failures of structural components in aggressive environments. SCC is even more harmful under cathodic conditions promoting the phenomenon known as hydrogen assisted cracking (HAC) hydrogen assisted fracture (HAF) or hydrogen embrittlement (HE). A common way to assess the susceptibility of a given material to HAC HAF or HE is to subject a cracked rod to a constant extension rate tension (CERT) test until it fractures in this harsh environment. This paper analyzes the influence of a residual stress field generated by fatigue precracking on the sample’s posterior susceptibility to HAC. To achieve this goal numerical simulations were carried out of hydrogen diffusion assisted by the stress field. Firstly a mechanical simulation of the fatigue precracking was developed for revealing the residual stress field after diverse cyclic loading scenarios and posterior stress field evolution during CERT loading. Afterwards a simulation of hydrogen diffusion assisted by stress was carried out considering the residual stresses after fatigue and the superposed rising stresses caused by CERT loading. Results reveal the key role of the residual stress field after fatigue precracking in the HAC phenomena in cracked steel rods as well as the beneficial effect of compressive residual stress.

A consortiumcomprising Cadent Gas Health and Safety Executive – Science Division ITMPower Keele University Northern Gas Networks and Progressive Energy is undertaking the second phase of the research project HyDeploy. The project the first two phase ofwhich are funded under the UK Network Innovation Competition scheme aims to demonstrate that natural gas containing levels of hydrogen beyond the upper limit set out in Schedule 3 of in the Gas Safety (Management) Regulations (GSMR) can be distributed and utilised safely and efficiently in the UK gas distribution networks.<br/>The first phase of the HyDeploy project concludes with a 10-month field trial in which hydrogen will be injected into part of a private gas distribution system owned and operated by Keele University.<br/>The second phase of the HyDeploy project (HyDeploy2) continues on from the work of the first phase and is scheduled to conclude with two 12-month field trials in which hydrogen will be injected into public gas networks owned and operated by Northern Gas Networks and Cadent Gas.<br/>Dave Lander Consulting Limited is providing technical support to the HyDeploy project and this report presents the results of Quantified Risk Assessment (QRA) for the proposed field trial of hydrogen injection into part of a gas distribution system owned and operated by Northern Gas Networks (NGN) near the town of Winlaton in Gateshead Tyne and Wear. The QRA is intended to support an application by NGN for exemption from the legal requirement to only convey gas that is compliant with the requirements of Schedule 3 of the GSMR. The QRA estimates the risk to persons within the trial area affected by the proposed injection. A similar QRA1 was developed for the original HyDeploy field trial at Keele University.<br/>Click on the supplement tab to see the other documents from this report

Exemption is requested by Northern Gas Networks Ltd (NGN) from the obligation set out in Regulation 8(1) of the Gas Safety (Management) Regulations 1996 (GSMR) to convey only natural gas that is compliant with the Interchangeability requirements of Part I of Schedule 3 of the GSMR within a section of the NGN gas distribution network near Winlaton (the “field trial area”). The field trial area is owned and operated by Northern Gas Networks Ltd. The proposed conveyance of non-compliant gas (hereafter called the “Winlaton Field Trial”) will last for one year and is part of the Network Innovation Competition Project “HyDeploy2”.<br/>The project the first two phases of which are funded under the UK Network Innovation Competition scheme aims to demonstrate that natural gas containing levels of hydrogen beyond the upper limit set out in Schedule 3 of in the Gas Safety (Management) Regulations (GSMR) can be distributed and utilised safely and efficiently in the UK gas distribution networks. The first phase of the HyDeploy project is currently underway and includes a 10-month field trial that of hydrogen injection into part of a private gas distribution system owned and operated by Keele University. The second phase of the HyDeploy project (HyDeploy2) continues on from the work of the first phase and is scheduled to conclude with two 12-month field trials in which hydrogen will be injected into public gas networks owned and operated by NGN and Cadent Gas.<br/>Click on the supplements tab to view the other documents from this report

In order to inform the Quantified Risk Assessment (QRA) and procedures for the Winlaton trial the HyDeploy 2 project has undertaken a second programme of work focused on assessing the safe operation of gas appliances with hydrogen blended gas. This work extends the initial programme of work undertaken in HyDeploy 1 in 2018. Collectively these two projects provide an evidence base to support the project objective to demonstrate that there are no overarching safety concerns for the addition of up to 20 % mol/mol hydrogen to the GB natural gas distribution network.<br/>Click on the supplements tab to view the other documents from this report

A rapid transition towards a CO2-neutral steel industry is required to limit climate change. Such a transition raises questions of justice as it entails positive and negative impacts unevenly distributed across societal stakeholders. To enable stakeholders to address such concerns this paper assesses the justice implications of three options that reduce emissions: CO2 capture and storage (CCS) on steel (up to 70%) bio-based steelmaking (up to 50%) and green hydrogen-based steel production (up to 100%). We select justice indicators from the energy climate labour and environmental justice literature and assess these indicators qualitatively for each of the technological routes based on literature and desk research. We find context-dependent differences in justness between the different technological routes. The impact on stakeholders varies across regions. There are justice concerns for local communities because of economic dependence on and environmental impact of the industry. Communities elsewhere are impacted through the siting of infrastructure and feedstock production. CCS and bio-based steelmaking routes can help retain industry and associated economic benefits on location while hydrogen-based steelmaking may deal better with environmental concerns. We conclude that besides techno-economic and environmental information transparency on sector-specific justice implications of transforming steel industries is essential for decision-making on technological routes