Transmission, Distribution & Storage

The demand for clean and sustainable energy solutions is escalating as the global population grows and economies develop. Fossil fuels which currently dominate the energy sector contribute to greenhouse gas emissions and environmental degradation. In response to these challenges hydrogen storage technologies have emerged as a promising avenue for achieving energy sustainability. This review provides an overview of recent advancements in hydrogen storage materials and technologies emphasizing the importance of efficient storage for maximizing hydrogen’s potential. The review highlights physical storage methods such as compressed hydrogen (reaching pressures of up to 70 MPa) and material-based approaches utilizing metal hydrides and carboncontaining substances. It also explores design considerations computational chemistry high-throughput screening and machine-learning techniques employed in developing efficient hydrogen storage materials. This comprehensive analysis showcases the potential of hydrogen storage in addressing energy demands reducing greenhouse gas emissions and driving clean energy innovation.

Hydrogen gas can provide baseload energy as society decarbonizes through the energy transition. Underground Hydrogen Storage (UHS) will be secure convenient and scalable to accommodate excess hydrogen production or compensate temporary shortfalls in energy supply. Hydrogen is a gas under all viable subsurface conditions so is invasive mobile and low-density. Methane and CO2 are also stored underground but storage parameters differ for each affecting the balance of geological storage risks. UHS in Australia is most likely to utilise conventional sedimentary reservoir rocks bound by conventional trapping closures. Hydrogen energy density will affect the competitiveness of UHS against purpose-built surface storage or solution-mined salt cavities. This study presents an overview of key considerations when screening for UHS opportunities and evaluates them for five Australian sedimentary basins. A threshold storage depth mapped across them reveals that the most prospective UHS basins will have to function as integrated energy fluid resource systems.

The NEWGASMET project has the overall objective to increase knowledge about the accuracy and durability of commercially available gas meters after exposure to renewable gases. This should lead to the improvement of existing meter designs and flow calibration standards. One of the recently released results is a proposal for a set of test gases to represent the range of non-conventional gases in the scope of the revision of the gas meter standards. In details these were proposed to be used in the CEN/TC237 standards and the OIML-R137:2014. During the project meetings concerns have been raised regarding the applicability of such test gases to EMC tests for static meters. Today such tests are performed in air but there is a clear agreement that the behaviour of the meter during EMC tests can be influenced by the renewable gas type. At least this agreement exists for the ultrasonic measurement technology while further discussion might be needed for the mass flow. However it is not simply possible to redesign the current EMC tests by replacing air with the defined gas mixtures as this would be quite impractical especially considering the explosive nature of the test gases.

Development of probabilistic modelling tools to perform Bayesian inference and uncertainty quantification (UQ) is a challenging task for practical hydrogen-enriched and low-emission combustion systems due to the need to take into account simultaneously simulated fluid dynamics and detailed combustion chemistry. A large number of evaluations is required to calibrate models and estimate parameters using experimental data within the framework of Bayesian inference. This task is computationally prohibitive in high-fidelity and deterministic approaches such as large eddy simulation (LES) to design and optimize combustion systems. Therefore there is a need to develop methods that: (a) are suitable for Bayesian inference studies and (b) characterize a range of solutions based on the uncertainty of modelling parameters and input conditions. This paper aims to develop a computationally-efficient toolchain to address these issues for probabilistic modelling of NOx emission in hydrogen-enriched and lean-premixed combustion systems. A novel method is implemented into the toolchain using a chemical reactor network (CRN) model non-intrusive polynomial chaos expansion based on the point collocation method (NIPCE-PCM) and the Markov Chain Monte Carlo (MCMC) method. First a CRN model is generated for a combustion system burning hydrogen-enriched methane/air mixtures at high-pressure lean-premixed conditions to compute NOx emission. A set of metamodels is then developed using NIPCE-PCM as a computationally efficient alternative to the physics-based CRN model. These surrogate models and experimental data are then implemented in the MCMC method to perform a two-step Bayesian calibration to maximize the agreement between model predictions and measurements. The average standard deviations for the prediction of exit temperature and NOx emission are reduced by almost 90% using this method. The calibrated model then used with confidence for global sensitivity and reliability analysis studies which show that the volume of the main-flame zone is the most important parameter for NOx emission. The results show satisfactory performance for the developed toolchain to perform Bayesian inference and UQ studies enabling a robust and consistent process for designing and optimising low-emission combustion systems.

This paper reviews previous research by the author in the field of hydrogen effects on progressively cold-drawn pearlitic steels in terms of hydrogen degradation (HD) hydrogen embrittlement (HE) or at the micro-level hydrogen-assisted micro-damage (HAMD) thus affecting their microstructural integrity and compromising the (macro-)structural integrity of civil engineering structures such as prestressed concrete bridges. It is seen that hydrogen effects in pearlitic microstructure (either oriented or not) are produced at the finest micro-level by plastic tearing in the form in general of hydrogen damage topography (HDT) with different appearances depending of the cold drawing degree evolving from the so-called tearing topography surface (TTS) in hot-rolled (not cold-drawn at all) or slightly cold-drawn pearlitic steels to a sort of enlarged and oriented TTS (EOTTS) in heavily drawn steels (the pronounced enlargement and marked orientation being along the wire axis or cold drawing direction). Whereas the pure TTS mode (null or low degree of cold drawing) resembles the Michelangello stone sculpture texture (MSST) the EOTTS mode does the same in relation to the Donatello wooden sculpture texture (DWST).

Electrochemical cells and systems play a key role in a wide range of industry sectors. These devices are critical enabling technologies for renewable energy; energy management conservation and storage; pollution control/monitoring; and greenhouse gas reduction. A large number of electrochemical energy technologies have been developed in the past. These systems continue to be optimized in terms of cost life time and performance leading to their continued expansion into existing and emerging market sectors. The more established technologies such as deep-cycle batteries and sensors are being joined by emerging technologies such as fuel cells large format lithium-ion batteries electrochemical reactors; ion transport membranes and supercapacitors. This growing demand (multi-billion dollars) for electrochemical energy systems along with the increasing maturity of a number of technologies is having a significant effect on the global research and development effort which is increasing in both in size and depth. A number of new technologies which will have substantial impact on the environment and the way we produce and utilize energy are under development. This paper presents an overview of several emerging electrochemical energy technologies along with a discussion some of the key technical challenges.

The geological storage of hydrogen is necessary to enable the successful transition to a hydrogen economy and achieve net-zero emissions targets. Comprehensive investigations must be undertaken for each storage site to ensure their long-term suitability and functionality. As such the systematic infrastructure and potential risks of large-scale hydrogen storage must be established. Herein we conducted over 250 batch reaction experiments with different types of reservoir sandstones under conditions representative of the subsurface reflecting expected time scales for geological hydrogen storage to investigate potential reactions involving hydrogen. Each hydrogen experiment was paired with a hydrogen-free control under otherwise identical conditions to ensure that any observed reactions were due to the presence of hydrogen. The results conclusively reveal that there is no risk of hydrogen loss or reservoir integrity degradation due to abiotic geochemical reactions in sandstone reservoirs.

Hydrogen can be used to enable decarbonisation of challenging applications such as provision of heat and as a fuel for heavy transport. The UK has set out a strategy for developing a new low carbon hydrogen sector by 2030. Underground storage will be a key component of any regional or national hydrogen network because of the variability of both supply and demand across different end-use applications. For storage of pure hydrogen salt caverns currently remain the only commercially proven subsurface storage technology implemented at scale. A new network of hydrogen storage caverns will therefore be required to service a low carbon hydrogen network. To facilitate planning for such systems this study presents a modelling approach used to evaluate the UK's theoretical hydrogen storage capacity in new salt caverns in bedded rock salt. The findings suggest an upper bound potential for hydrogen storage exceeding 64 million tonnes providing 2150 TWh of storage capacity distributed in three discrete salt basins in the UK. The modelled cavern capacity has been interrogated to identify the practical inter-seasonal storage capacity suitable for integration in a hydrogen transmission system. Depending on cavern spacing a peak load deliverability of between 957 and 1876 GW is technically possible with over 70% of the potential found in the East Yorkshire and Humber region. The range of geologic uncertainty affecting the estimates is approximately ±36%. In principle the peak domestic heating demand of approximately 170 GW across the UK can be met using the hydrogen withdrawn from caverns alone albeit in practice the storage potential is unevenly distributed. The analysis indicates that the availability of salt cavern storage potential does not present a limiting constraint for the development of a low-carbon hydrogen network in the UK. The general framework presented in this paper can be applied to other regions to estimate region-specific hydrogen storage potential in salt caverns.

The R&D project H2STORE is part of the German program to reduce environmental pollution by energy production and in saving fossil natural resources. Thereby physico-chemical processes in the CO2-H2 system by organic and inorganic reactions receive increasing attention. In H2STORE siliciclastic reservoirs and their caprocks from 25 well sites in Germany and Austria are investigated by different analytical methods before and after H2/CO2 batch experiments under sample specific reservoir conditions (p T XFluid). Mineral dissolution precipitation and their impact on reservoir quality (poro-perm fluid pathways) and on the generation of methane by microbial metabolism triggered by CO2/H2 exposure are studied.

Hydrogen can be a renewable energy carrier and is suggested to store renewable energy and mitigate carbon dioxide emissions. Subsurface storage of hydrogen in salt caverns deep saline formations and depleted oil/gas reservoirs would help to overcome imbalances between supply and demand of renewable energy. Hydrogen however is one of the most important electron donors for many subsurface microbial processes including methanogenesis sulfate reduction and acetogenesis. These processes cause hydrogen loss and changes of reservoir properties during geological hydrogen storage operations. Here we report the results of a typical halophilic sulfate-reducing bacterium growing in a microfluidic pore network saturated with hydrogen gas at 35 bar and 37°C. Test duration is 9 days. We observed a significant loss of H2 from microbial consumption after 2 days following injection into a microfluidic device. The consumption rate decreased over time as the microbial activity declined in the pore network. The consumption rate is influenced profoundly by the surface area of H2 bubbles and microbial activity. Microbial growth in the silicon pore network was observed to change the surface wettability from a water-wet to a neutral-wet state. Due to the coupling effect of H2 consumption by microbes and wettability alteration the number of disconnected H2 bubbles in the pore network increased sharply over time. These results may have significant implications for hydrogen recovery and gas injectivity. First pore-scale experimental results reveal the impacts of subsurface microbial growth on H2 in storage which are useful to estimate rapidly the risk of microbial growth during subsurface H2 storage. Second microvisual experiments provide critical observations of bubble-liquid interfacial area and reaction rate that are essential to the modeling that is needed to make long-term predictions. Third results help us to improve the selection criteria for future storage sites.