Publications

The world is facing an urgent global climate challenge and hydrogen (H2) is increasingly valued as a carbon-free energy carrier that can play a prominent role in decarbonising economies. However the environmental impact of the different methods for hydrogen production are sometimes overlooked. This work provides a comprehensive overview of the environmental impacts and costs of a diverse range of methods for producing hydrogen. Ninety nine life cycle assessments (LCAs) of hydrogen production published between 2015 and 2022 are categorised by geography production method energy source goal and scope and compared by data sources and methodology. A meta-analysis of methodological choices is used to identify a subset of mutually comparable studies whose results are then compared initially by global warming potential (GWP) then low-GWP scenarios are compared by other indicators. The results show that the lowest GWP is achieved by methods that are currently more expensive (~US $4–9/kg H2) compared to the dominant methods of producing hydrogen from fossil fuels (~US $1–2/kg H2). The research finds that data are currently limited for comparing environmental indicators other than GWP such as terrestrial acidification or freshwater eutrophication. Recommendations are made for future LCAs of hydrogen production.

Recently major problems related to fuel consumption and greenhouse gas (GHG) emissions have arisen in the transportation sector. Therefore developing transportation modes powered by alternative fuels has become one of the main targets for car manufacturers and governments around the world. This study aimed to investigate the economic prospects of using hydrogen fuel cell technology in taxi fleets in Westbank. For this purpose a model that could predict the number of taxis was developed and the expected economic implications of using hydrogen fuel cell technology in taxi fleets were determined based on the expected future fuel consumption and future fuel cost. After analysis of the results it was concluded that a slight annual increase in the number of taxis in Palestine is expected in the future due to the government restrictions on issuing new taxi permits in order to get this sector organized. Furthermore using hydrogen fuel cells in taxi fleets is expected to become more and more feasible over time due to the expected future increase in oil price and the expected significant reduction in hydrogen cost as a result of the new technologies that are expected to be used in the production and handling of hydrogen.

In this podcast David Ledesma talks to Aliaksei Patonia and Veronika Lenivova about Hydrogen pipelines and high-voltage direct current (HVDC) transmission lines and how Hydrogen pipelines offer the advantage of transporting larger energy volumes but existing projects are dwarfed by the vast networks of HVDC transmission lines. The podcast discusses how advocates for hydrogen pipelines see potential in expanding these networks capitalizing on hydrogen’s physical similarities to natural gas and the potential for cost savings. However hydrogen’s unique characteristics such as its small molecular size and compression requirements present construction challenges. On the other hand HVDC lines while less voluminous excel in efficiently transmitting green electrons over long distances. They already form an extensive global network and their efficiency makes them suitable for various applications. Yet intermittent renewable energy sources pose challenges for both hydrogen and electricity systems necessitating solutions like storage and blending.

The podcast can be found on their website.

One of the methods for mitigating the duck curve phenomenon in photovoltaic (PV) energy systems is storing surplus energy in the form of hydrogen. However there is a lack of studies focused on residential PV systems that assess the impact of hydrogen storage on the reduction of energy flow imbalance to and from the national grid. This study presents an analysis of hydrogen energy storage based on real-world data from a household PV installation. Using simulation methods grounded in actual electricity consumption and hourly PV production data the research identified the storage requirements including the required operating hours and the capacity of the hydrogen tank. The analysis was based on a 1 kW electrolyzer and a fuel cell representing the smallest and most basic commercially available units and included a sensitivity analysis. At the household level—represented by a singlefamily home with an annual energy consumption and PV production of approximately 4–5 MWh over a two-year period—hydrogen storage enabled the production of 49.8 kg and 44.6 kg of hydrogen in the first and second years respectively. This corresponded to the use of 3303 kWh of PV-generated electricity and an increase in self-consumption from 30% to 64%. Hydrogen storage helped to smooth out peak energy flows from the PV system decreasing the imbalance from 5.73 kWh to 4.42 kWh. However while it greatly improves self-consumption its capacity to mitigate power flow imbalance further is constrained; substantial improvements would necessitate a much larger electrolyzer proportional in size to the PV system’s output.

Underground Hydrogen Storage (UHS) provides a large-scale and safe solution to balance the fluctuations in energy production from renewable sources and energy consumption but requires a proper and detailed characterization of the candidate reservoirs. The scope of this study was to estimate the hydrogen diffusion coefficient for real caprock samples from two natural gas storage reservoirs that are candidates for underground hydrogen storage. A significant number of adsorption/desorption tests were carried out using a Dynamic Gravimetric Vapor/Gas Sorption System. A total of 15 samples were tested at the reservoir temperature of 45 °C and using both hydrogen and methane. For each sample two tests were performed with the same gas. Each test included four partial pressure steps of sorption alternated with desorption. After applying overshooting and buoyancy corrections the data were then interpreted using the early time approximation of the solution to the diffusion equation. Each interpretable partial pressure step provided a value of the diffusion coefficient. In total more than 90 estimations of the diffusion coefficient out of 120 partial pressure steps were available allowing a thorough comparison between the diffusion of hydrogen and methane: hydrogen in the range of 1 × 10−10 m2 /s to 6 × 10−8 m2 /s and methane in the range of 9 × 10−10 m2 /s to 2 × 10−8 m2 /s. The diffusion coefficients measured on wet samples are 2 times lower compared to those measured on dry samples. Hysteresis in hydrogen adsorption/desorption was also observed.

The main results highlighted in this article underline the critical significance of hydrogen technologies in the move towards carbon neutrality. This research focuses on several key areas including the production storage safety and usage of hydrogen alongside innovative approaches for assessing hydrogen purity and production-related technologies. This study emphasizes the vital role of hydrogen storage technology for the future utilization of hydrogen as an energy carrier and the advancement of technologies that facilitate effective safe and cost-efficient hydrogen storage. Furthermore bibliometric analysis has been instrumental in identifying primary research fields such as hydrogen storage hydrogen production efficient electrocatalysts rotary engines utilizing hydrogen as fuel and underground hydrogen storage. Each domain is essential for realizing a sustainable hydrogen economy reflecting the significant research and development efforts in hydrogen technologies. Recent trends have shown an increased interest in underground hydrogen storage as a method to enhance energy security and assist in the transition towards sustainable energy systems. This research delves into the technical economic and environmental facets of employing geological formations for large-scale seasonal and long-term hydrogen storage. Ultimately the development of hydrogen technologies is deemed crucial for meeting sustainable development goals particularly in terms of addressing climate change and reducing greenhouse gas emissions. Hydrogen serves as an energy carrier that could substantially lessen reliance on fossil fuels while encouraging the adoption of renewable energy sources aiding in the decarbonization of transport industry and energy production sectors. This in turn supports worldwide efforts to curb global warming and achieve carbon neutrality.

Blending hydrogen to existing fuel mix represents a major opportunity for decarbonisation. One important consideration for this application is the chemical interaction between hydrogen and hydrocarbon fuels arising from their different combustion chemistries and varying considerably with combustion processes. This paper conducted an exploratory study of hydrogen’s impact on autoignition in several combustion processes where hydrogen is used as a blending component or the main fuel. Case studies are presented for spark ignition engines (H2/natural gas) compression ignition engines (H2/diesel) moderate or intense low-oxygen dilution (MILD) combustors (H2/natural gas) and rotational detonation engines (H2/natural gas). Autoignition reactivity as a function of the hydrogen blending level is investigated numerically using the ignition delay iso-contours and state-of-the-art kinetic models at time scales representative of each application. The results revealed drastically different impact of hydrogen blending on autoignition due to different reaction temperature pressure and time scale involved in these applications leaving hydrocarbon interacting with hydrogen at different ignition branches where the negative pressure/temperature dependency of oxidation kinetics could take place. The resulted non-linear and at times non-monotonic behaviours indicate a rich topic for combustion chemistry and also demonstrates ignition delay iso-contour as a useful tool to scope autoignition reactivity for a wide range of applications.

This review presents a state-of-the-art of geochemical geomechanical and hydrodynamic modelling studies in the Underground Hydrogen Storage (UHS) domain. Geochemical modelling assessed the reactivity of hydrogen and res pective fluctuations in hydrogen losses using kinetic reaction rates rock mineralogy brine salinity and the integration of hydrogen redox reactions. Existing geomechanics studies offer an array of coupled hydromechanical models suggesting a decline in rock failure during the withdrawal phase in aquifers compared to injection phase. Hydrodynamic modelling evaluations indicate the critical importance of relative permeability hysteresis in determining the UHS performance. Solubility and diffusion of hydrogen gas appear to have minimal impact on UHS. Injection and production rates cushion gas deployment and reservoir heterogeneity however significantly affect the UHS performance stressing the need for thorough modelling and experimental studies. Most of the current UHS modelling efforts focus on assessing the hydrodynamic aspects which are crucial for understanding the viability and safety of UHS. In contrast the lesser-explored geochemical and geomechanical considerations point to potential research gaps. A variety of modelling software tools such as CMG Eclipse COMSOL and PHREEQC evaluated those UHS underlying effects along with a few recent applications of datadriven-based Machine Learning (ML) techniques for enhanced accuracy. This review identified several unresolved challenges in UHS modelling: pronounced lack of expansive datasets leading to a gap between model predictions and their practical reliability; need robust methodologies capable of capturing natural subsurface heterogeneity while upscaling from precise laboratory data to field-scale conditions; demanding intensive computational resources and novel strategies to enhance simulation efficiency; and a gap in addressing geological uncertainties in subsurface environments suggesting that methodologies from oil reservoir simulations could be adapted for UHS. This comprehensive review offers a critical synthesis of the prevailing approaches challenges and research gaps in the domain of UHS thus providing a valuable reference document for further modelling efforts facilitating the informed advancements in this critical domain towards the realization of sustainable energy solutions.

Based on the concept of sustainable development to promote the development and application of renewable energy and enhance the capacity of renewable energy consumption this paper studies the design and optimization of renewable energy hydrogen production systems. For this paper six different scenarios for grid-connected and off-grid renewable energy hydrogen production systems were designed and analyzed economically and technically and the optimal grid-connected and off-grid systems were selected. Subsequently the optimal system solution was optimized by analyzing the impact of the load data and component capacity on the grid dependency of the grid-connected hydrogen production system and the excess power rate of the off-grid hydrogen production system. Based on the simulation results the most matched load data and component capacity of different systems after optimization were determined. The grid-supplied power of the optimized grid-connected hydrogen production system decreased by 3347 kWh and the excess power rate of the off-grid hydrogen production system decreased from 38.6% to 10.3% resulting in a significant improvement in the technical and economic performance of the system.

Hydrogen is widely considered as the energy carrier of the future but the rather high energy losses for its production are often neglected. The major current hydrogen production technology is steam methane reforming of fossil gas but there is a growing interest in producing hydrogen sustainably from water using electrolysis. This article examines four main hydrogen production chains and two transportation options (pipeline and ship) from North Africa to Europe analyzing the costs and environmental impacts of each. The core objective is to determine the most promising hydrogen provision method and location from an economic and ecological point of view including the required transport. An important finding of this analysis is that both options importing green hydrogen and producing it in Europe may be relevant for a decarbonized energy system. The emphasis should be on green hydrogen to achieve carbon emission reductions. If blue hydrogen is also considered attention should be paid to the often-neglected methane emissions upstream.