Publications

Considerable progress has been made recently in the use of nanoporous materials for hydrogen storage. In this article the current status of the field and future challenges are discussed ranging from important open fundamental questions such as the density and volume of the adsorbed phase and its relationship to overall storage capacity to the development of new functional materials and complete storage system design. With regard to fundamentals the use of neutron scattering to study adsorbed H2 suitable adsorption isotherm equations and the accurate computational modelling and simulation of H2 adsorption are discussed. The new materials covered include flexible metal–organic frameworks core–shell materials and porous organic cage compounds. The article concludes with a discussion of the experimental investigation of real adsorptive hydrogen storage tanks the improvement in the thermal conductivity of storage beds and new storage system concepts and designs.

Airlines are faced with the challenge of reducing their environmental footprint in an effort to push for climate-neutral initiatives that comply with international regulations. In the past the aviation industry has followed the approach of incremental improvement of fuel efficiency while simultaneously experiencing significant growth in annual air traffic. With the increase in air traffic negating any reduction in Greenhouse Gas (GHG) emissions more disruptive technologies such as hydrogen-based onboard power generation are required to reduce the environmental impact of airline operations. However despite initial euphoria and first conceptual studies for hydrogen-powered aircraft several decades ago there still has been no mass adoption to this day. Besides the challenges of a suitable ground infrastructure this can partly be attributed to uncertainties with the associated maintenance requirements and the expected operating costs to demonstrate the economic viability of this technology. With this study we address this knowledge gap by estimating changes towards scheduled maintenance activities for an airborne hydrogen storage and distribution system. In particular we develop a detailed system design for a hydrogen-powered fuel-cell-based auxiliary power generation and perform a comparative analysis with an Airbus A320 legacy system. That analysis allows us to (a) identify changes for the expected maintenance effort to enhance subsequent techno-economic assessments (b) identify implications of specific design assumptions with corresponding maintenance activities while ensuring regulatory compliance and (c) describe the impact on the resulting task execution. The thoroughly examined interactions between system design and subsequent maintenance requirements of this study can support practitioners in the development of prospective hydrogen-powered aircraft. In particular it allows the inclusion of maintenance implications in early design stages of corresponding system architectures. Furthermore since the presented methodology is transferable to different design solutions it provides a blueprint for alternative operating concepts such as the complete substitution of kerosene by hydrogen to power the main engines.

This study proposes a predictive equivalent consumption minimization strategy (P-ECMS) that utilizes velocity prediction and considers various dynamic constraints to mitigate fuel cell degradation assessed using a dedicated sub-model. The objective is to reduce fuel consumption in real-world conditions without prior knowledge of the driving mission. The P-ECMS incorporates a velocity prediction layer into the Energy Management System. Comparative evaluations with a conventional adaptive-ECMS (A-ECMS) a standard ECMS with a well-tuned constant equivalence factor and a rule-based strategy (RBS) are conducted across two driving cycles and three fuel cell dynamic restrictions (|∕| ≤ 0.1 0.01 and 0.001 A∕cm2 ). The proposed strategy achieves H2 consumption reductions ranging from 1.4% to 3.0% compared to A-ECMS and fuel consumption reductions of up to 6.1% when compared to RBS. Increasing dynamic limitations lead to increased H2 consumption and durability by up to 200% for all tested strategies.

There is an impetus to decarbonize transportation sector and mitigate climate change. This study examines the effect of adopting hydrogen (H2) as a fuel for Dubai Buses at different penetration scales on carbon dioxide (CO2) emissions reduction. A H2 supply-chain system dynamics model is developed to conduct life cycle cost and environmental analysis and evaluate the efficacy of different carbon prices and subsidies. Gray green and mixed H2 production scenarios were considered. The results show that gray hydrogen reduces 7.1 million tons of CO2 which is half of green hydrogen buses. Replacing diesel fleet at end of lifetime with mixed hydrogen bus fleet was the optimal approach to promote green hydrogen at pump reaching $4/kg in a decade. This gradual transition reduces 62% of the well-to-wheel CO2 emissions of the new bus fleet and creates mass for economies of scale as carbon prices and subsidies cannot promote green hydrogen alone.

Especially the electrification of the industry sector is highly complex and challenging mainly due to process-specific requirements. In this context there are several industrial processes where the direct and indirect use of electricity is subject to technical restrictions. In order to achieve the national climate goals the fossil energy consumption remaining after the implementation of efficiency and sufficiency measures as well as direct electrification has to be substituted through hydrogen and synthetic gaseous liquid and solid hydrocarbons. As the main research object the role of synthetic fuels in industrial transformation paths is investigated and analyzed by combining individual greenhouse gas abatement measures within the Sector Model Industry. Sector Model Industry is an energy consumption model that performs discrete deterministic energy and emission dynamic calculations with a time horizon up to 2050 at macroeconomic level. The results indicate that the use of synthetic fuels can be expected with a high level of climate protection. The industrial CO2 target in the model makes it necessary to replace CO2 -intensive fossil with renewable fuels. The model uses a total of 163 TWh of synthetic fuels in the climate protection scenario and thus achieves an 88% decrease in CO2 emissions in 2050 compared to 1990. This means that the GHG abatement achieved in industry is within the range of the targeted CO2 mitigation of the overall system in Germany of between 80 and 95% in 2050 compared to 1990. Due to technical restrictions the model mainly uses synthetic methane instead of hydrogen (134 TWh). The results show that despite high costs synthetic fuels are crucial for defossilization as a fall back option in the industrial scenario considering high climate ambition. The scenario does not include hydrogen technologies for heat supply. Accordingly the climate protection scenario uses hydrogen only in the steel industry for the direct reduction of iron (21 TWh). 8 TWh of synthetic oil substitute the same amount of fossil oil in the climate protection scenario. A further analysis conducted on the basis of the model results shows that transformation in the energy system and the use of smart ideas concepts and technologies are a basic prerequisite for enabling the holistic defossilisation of industry. The findings in the research can contribute to the cost-efficient use of synthetic fuels in industry and thus serve as a basis for political decision making. Moreover the results may have a practical relevance not only serving as a solid comparison base for the outcome of other studies but also as input data for further simulation of energy system transformation paths.

With the adoption of the EU Climate Law in 2021 the EU has set itself a binding target to achieve climate neutrality by 2050 and to reduce greenhouse gas emissions by 55 percent compared to 1990 levels by 2030. To support the increased ambition the EU Commission adopted proposals for revising the key directives and regulations addressing energy efficiency renewable energies and greenhouse gas emissions in the Fit for 55 package. The heating and cooling (H&C) sector plays a key role for reaching the EU energy and climate targets. H&C accounts for about 50 percent of the final energy consumption in the EU and the sector is largely based on fossil fuels. In 2021 the share of renewable energies in H&C reached 23%.

Hydrogen embrittlement (HE) is a critical concern for pipeline steels particularly as the energy sector explores the feasibility of blending hydrogen with natural gas to reduce carbon emissions. Various mechanical testing methods assess HE with fracture toughness testing offering a quantitative measure of defect impacts on structural safety particularly for cracks arising during manufacturing fabrication or in-service conditions. This study focuses on assessing the fracture toughness of two pipeline steels from an existing natural gas network under varying hydrogen concentrations using double cantilever beam (DCB) fracture tests. A vintage API X52 steel with a ferritic–pearlitic microstructure and a modern API X65 steel with polygonal ferrite and elongated pearlite colonies were selected to represent old and new pipeline materials. Electrochemical hydrogen charging was employed to simulate hydrogen exposure with the charging parameters derived from hydrogen permeation tests. The results highlight the differing impacts of hydrogen on the fracture toughness and crack growth in vintage and modern pipeline steels. These findings are essential for ensuring the safety and integrity of pipelines carrying hydrogen–natural gas blends.

This article challenges the view that zero carbon hydrogen from steam methane reforming (SMR) is prohibitively expensive and that the cost of CO2 capture increases exponentially as residual emissions approach zero; a flawed narrative often eliminating SMR produced hydrogen as a route to net zero. We show that the capture and geological storage of 100% of the fossil CO2 produced in a SMR is achievable with commercially available post-combustion capture technology and an open art solvent. The Levelised Cost of Hydrogen (LCOH) of 69£/MWhth HHV (2.7£/kg) for UK production remains competitive to other forms of low carbon hydrogen but retains a hydrogen lifecycle carbon intensity of 5 gCO2e/MJ (LHV) due to natural gas supply chain and embodied greenhouse gas (GHG) emissions. Compensating for the remaining lifecycle GHG emissions via Direct Air Capture with geological CO2 Storage (DACCS) increases the LCOH to 71–86 £/MWhth HHV (+3–25%) for a cost estimate of 100–1000 £/tCO2 for DACCS and the 2022 UK natural gas supply chain methane emission rates. Finally we put in perspective the cost of CO2 avoidance of fuel switching from natural gas to hydrogen with long term price estimates for natural gas use and DACCS and hydrogen produced from electrolysis.

Land-based gas turbines (GTs) are continuous-flow engines that run with permanent flames once started and at stationary pressure temperature and flows at stabilized load. Combustors operate without any moving parts and their substantial air excess enables complete combustion. These features provide significant space for designing efficient and versatile combustion systems. In particular as heavy-duty gas turbines have moderate compression ratios and ample stall margins they can burn not only high- and medium-BTU fuels but also low-BTU ones. As a result these machines have gained remarkable fuel flexibility. Dry Low Emissions combustors which were initially confined to burning standard natural gas have been gradually adapted to an increasing number of alternative gaseous fuels. The paper first delivers essential technical considerations that underlie this important fuel portfolio. It then reviews the spectrum of alternative GT fuels which currently extends from lean gases (coal bed coke oven blast furnace gases . . . ) to rich refinery streams (LPG olefins) and from volatile liquids (naphtha) to heavy hydrocarbons. This “fuel diet” also includes biogenic products (biogas biodiesel and ethanol) and especially blended and pure hydrogen the fuel of the future. The paper also outlines how historically land-based GTs have gradually gained new fuel territories thanks to continuous engineering work lab testing experience extrapolation and validation on the field.

Mitigation of carbon dioxide (CO2) emission has been a worldwide concern. Decreasing CO2 emission by converting it into higher value products such as methanol can be a promising way. However hydrogen (H2) cost and availability are one of key barriers to CO2 conversion. Ethanol can be a sustainable source for H2 due to its renewable nature and easy conversion to H2-rich gas mixtures through ethanol steam reforming process. Nevertheless steam reforming of ethanol generates CO2. Hence this research is focused on different methods of H2 productions about a 1665.47 t/y from ethanol for supplying to methanol plants was performed using Aspen PLUS V10. The ethanol steam reforming process required the lowest required ethanol feed for a certain amount of H2. In contrast the ethanol steam reforming process presented significant amount of CO2 emission from reaction and electricity consumption. But the ethanol dehydrogenation of ethanol not only generates H2 without CO2 emission from the reaction but also ethyl acetate or acetaldehyde which are value chemicals. However ethanol dehydrogenation processes in case II and III presented relatively higher cost because by-products (ethyl acetate or acetaldehyde) were rather difficult to be separated.