Publications

To situate its low-carbon transition process in longer-term real-world business contexts this article makes a longitudinal analysis of the UK petrochemical industry focusing on changing economic and socio-political environments and company strategies in the last 50 years. Using the Triple Embeddedness Framework the paper identifies two parallel and conflicting reorientation processes in the UK petrochemical industry. The first one which started in the 1970s and is driven by long-standing competitiveness problems led to retrenchment in the 1980s exit of incumbent companies (BP Shell ICI) and the entry of new firms (INEOS SABIC) in the 1990s and 2000s and diversification into upstream fossil fuel production and ethane imports in the 2010s. The second reorientation process which started in the 2010s is driven by climate change considerations and has led petrochemical firms to reluctantly explore low-carbon alternatives. Despite advancing ambitious visions and plans companies are weakly committed to low-carbon reorientation because this is layered on top of and conflicts with the deeper economically-motivated reorientation process. The paper further concludes that the industry's low-carbon plans and visions are partial because they focus more on some innovations (hydrogen-as-fuel CCS) than on other innovations (recycling bio-feedstocks synthetic feedstocks). Despite exploring alternatives firms also use political resistance strategies to hamper and delay deeper low-carbon reorientation

In this episode titled "The Commission's support to the hydrogen ecosystem" our CEO Jorgo Chatzimarkakis discusses with Rosalinde van der Vlies Clean Planet Director DG RTD - European Commission. Starting off on how Rosalinde joined the Commission the two speakers discuss the Commission's support in developing a hydrogen ecosystem also in light of its participation in the Clean Hydrogen Partnership and the implications arising from the REPowerEU.

The impact of hydrogen added to natural gas on the performance of commercial domestic water heating devices has been discussed in several recent papers in the literature. Much of the work focuses on performance at specific hydrogen levels (by volume) up to 20–30% as a near term blend target. In the current work new data on several commercial devices have been obtained to help quantify upper limits based on flashback limits. In addition results from 39 individual devices are compiled to help generalize observations regarding performance. The emphasis of this work is on emissions performance and especially NOx emissions. It is important to consider the reporting bases of the emissions numbers to avoid any unitended bias. For water heaters the trends associated with both mass per fuel energy input and concentration-based representation are similar For carbon free fuels bases such as 12% CO2 should be avoided. In general the compiled data shows that NOx NO UHC and CO levels decrease with increasing hydrogen percentage. The % decrease in NOx and NO is greater for low NOx devices (meaning certified to NOx <10 ng/J using premixing with excess air) compared to conventional devices (“pancake burners” partial premixing). Further low NOx devices appear to be able to accept greater amounts of hydrogen above 70% hydrogen in some cases without modification while conventional water heaters appear limited to 40–50% hydrogen. Reporting emissions on a mass basis per unit fuel energy input is preferred to the typical dry concentration basis as the greater amount of water produced by hydrogen results in a perceived increase in NOx when hydrogen is used. While this effort summarizes emissions performance with added hydrogen additional work is needed on transient operation higher levels of hydrogen system durability/reliability and heating efficiency.

Transportation is one of the largest sources of CO2 emissions accounting for more than 20% of worldwide emissions. However it is one of the areas where decarbonization presents the greatest hurdles owing to its capillarity and the benefits that are associated with the use of fossil fuels in terms of energy density storage and transportation. In order to accomplish comprehensive decarbonization in the transport sector it will be required to encourage a genuine transition to low-carbon fuels and the widespread deployment of the necessary infrastructures to allow for a large-scale innovation. Renewable hydrogen shows potential for sustainable transportation applications whether in fuel cell electric vehicles (FCEVs) such as automobiles trucks and trains or as a raw material for ship and airplane synthetic fuels. The present paper aims to present how hydrogen-fuel cell hybrid powertrains for road vehicles work in terms of conceptual layouts and operating strategies. A comprehensive overview of real and current applications is presented concerning existing prototypes and commercially available vehicles with a focus on the main key performance indicators such as efficiency mileage and energy consumption.

In this paper the design of fuel cells for the main energy supply of passenger transportation aircraft is discussed. Using a physical model of a fuel cell general design considerations are derived. Considering different possible design objectives the trade-off between power density and efficiency is discussed. A universal cost–benefit curve is derived to aid the design process. A weight factor wP is introduced which allows incorporating technical (e.g. system mass and efficiency) as well as non-technical design objectives (e.g. operating cost emission goals social acceptance or technology affinity political factors). The optimal fuel cell design is not determined by the characteristics of the fuel cell alone but also by the characteristics of the other system components. The fuel cell needs to be designed in the context of the whole energy system. This is demonstrated by combining the fuel cell model with simple and detailed design models of a liquid hydrogen tank. The presented methodology and models allows assessing the potential of fuel cell systems for mass reduction of future passenger aircraft.

Hydrogen is considered the fuel of the future due to its cleaner nature compared to methane and gasoline. Therefore renewable hydrogen production technologies and long-term affordable and safe storage have recently attracted significant research interest. However natural underground hydrogen production and storage have received scant attention in the literature despite its great potential. As such the associated formation mechanisms geological locations and future applications remain relatively under-explored thereby requiring further investigation. In this review the global natural hydrogen formation along with reaction mechanisms (i.e. metamorphic processes pyritization and serpentinization reactions) as well as the suitable geological locations (i.e. ophiolites organic-rich sediments fault zones igneous rocks crystalline basements salt bearing strata and hydrocarbon-bearing basins) are discussed. Moreover the underground hydrogen storage mechanisms are detailed and compared with underground natural gas and CO2 storage. Techno-economic analyses of large-scale underground hydrogen storage are presented along with the current challenges and future directions.

This review article provides a comprehensive overview of the fundamentals modelling approaches experimental studies and challenges associated with hydrogen gas flow in pipelines. It elucidates key aspects of hydrogen gas flow including density compressibility factor and other relevant properties crucial for understanding its behavior in pipelines. Equations of state are discussed in detail highlighting their importance in accurately modeling hydrogen gas flow. In the subsequent sections one-dimensional and three-dimensional modelling techniques for gas distribution networks and localized flow involving critical components are explored. Emphasis is placed on transient flow friction losses and leakage characteristics shedding light on the complexities of hydrogen pipeline transportation. Experimental studies investigating hydrogen pipeline transportation dynamics are outlined focusing on the impact of leakage on surrounding environments and safety parameters. The challenges and solutions associated with repurposing natural gas pipelines for hydrogen transport are discussed along with the influence of pipeline material on hydrogen transportation. Identified research gaps underscore the need for further investigation into areas such as transient flow behavior leakage mitigation strategies and the development of advanced modelling techniques. Future perspectives address the growing demand for hydrogen as a clean energy carrier and the evolving landscape of hydrogen-based energy systems.

Across the globe energy production and usage cause the greatest greenhouse gas (GHG) emissions which are the key driver of climate change. Therefore countries around the world are aggressively striving to convert to a clean energy regime by altering the ways and means of energy production. Hydrogen is a frontrunner in the race to net-zero carbon because it can be produced using a diversity of feedstocks has versatile use cases and can help ensure energy security. While most current hydrogen production is highly carbon-intensive advances in carbon capture renewable energy generation and electrolysis technologies could help drive the production of low-carbon hydrogen. However significant challenges such as the high cost of production a relatively small market size and inadequate infrastructure need to be addressed before the transition to a hydrogen-based economy can be made. This review presents the state of hydrogen demand challenges in scaling up low-carbon hydrogen possible solutions for a speedy transition and a potential course of action for nations.

Dynamically-operated water electrolyzers enable the production of green hydrogen for cross-sector applications while simultaneously stabilizing power grids. In this study the start-up phase of polymer electrolyte membrane (PEM) water electrolyzers is investigated in the context of intermittent renewable energy sources. During the start-up of the electrolysis system the temperature increases which directly influences hydrogen production efficiency. Experiments on a 100 kWel electrolyzer combined with simulations of electrolyzers with up to 1 MWel were used to analyze the start-up phase and assess its implications for operators and system designers. It is shown that part-load start-up at intermediate cell voltages of 1.80 V yields the highest efficiencies of 74.0 %LHV compared to heat-up using resistive electrical heating elements which reaches maximum efficiencies of 60.9 %LHV. The results further indicate that large-scale electrolyzers with electrical heaters may serve as flexible sinks in electrical grids for durations of up to 15 min.

Hydrogen is emerging as one of the most promising energy carriers for a decarbonised global energy system. Transportation and storage of hydrogen are critical to its large-scale adoption and to these ends liquid hydrogen is being widely considered. The liquefaction and storage processes must however be both safe and efficient for liquid hydrogen to be viable as an energy carrier. Identifying the most promising liquefaction processes and associated transport and storage technologies is therefore crucial; these need to be considered in terms of a range of interconnected parameters ranging from energy consumption and appropriate materials usage to considerations of unique liquid-hydrogen physics (in the form of ortho–para hydrogen conversion) and boil-off gas handling. This study presents the current state of liquid hydrogen technology across the entire value chain whilst detailing both the relevant underpinning science (e.g. the quantum behaviour of hydrogen at cryogenic temperatures) and current liquefaction process routes including relevant unit operation design and efficiency. Cognisant of the challenges associated with a projected hydrogen liquefaction plant capacity scale-up from the current 32 tonnes per day to greater than 100 tonnes per day to meet projected hydrogen demand this study also reflects on the next-generation of liquid-hydrogen technologies and the scientific research and development priorities needed to enable them.