Publications

One of the emerging and environmentally friendly technologies is the photoelectrochemical generation of green hydrogen; however the cheap cost of production and the need for customizing photoelectrode properties are thought to be the main obstacles to the widespread adoption of this technology. The primary players in hydrogen production by photoelectrochemical (PEC) water splitting which is becoming more common on a worldwide basis are solar renewable energy and widely available metal oxide based PEC electrodes. This study attempts to prepare nanoparticulate and nanorod-arrayed films to better understand how nanomorphology can impact structural optical and PEC hydrogen production efficiency as well as electrode stability. Chemical bath deposition (CBD) and spray pyrolysis are used to create ZnO nanostructured photoelectrodes. Various characterization methods are used to investigate morphologies structures elemental analysis and optical characteristics. The crystallite size of the wurtzite hexagonal nanorod arrayed film was 100.8 nm for the (002) orientation while the crystallite size of nanoparticulate ZnO was 42.1 nm for the favored (101) orientation. The lowest dislocation values for (101) nanoparticulate orientation and (002) nanorod orientation are 5.6 × 10−4 and 1.0 × 10−4 dislocation/nm2 respectively. By changing the surface morphology from nanoparticulate to hexagonal nanorod arrangement the band gap is decreased to 2.99 eV. Under white and monochromatic light irradiation the PEC generation of H2 is investigated using the proposed photoelectrodes. The solar-to-hydrogen conversion rate of ZnO nanorod-arrayed electrodes was 3.72% and 3.12% respectively under 390 and 405 nm monochromatic light which is higher than previously reported values for other ZnO nanostructures. The output H2 generation rates for white light and 390 nm monochromatic illuminations were 28.43 and 26.11 mmol.h−1 cm−2 respectively. The nanorod-arrayed photoelectrode retains 96.6% of its original photocurrent after 10 reusability cycles compared to 87.4% for the nanoparticulate ZnO photoelectrode. The computation of conversion efficiencies H2 output rates Tafel slope and corrosion current as well as the application of low-cost design methods for the photoelectrodes show how the nanorod-arrayed morphology offers low-cost high-quality PEC performance and durability.

This study investigates the techno-economic feasibility of an off-grid integrated solar/wind/hydrokinetic plant to co-generate electricity and hydrogen for a remote micro-community. In addition to the techno-economic viability assessment of the proposed system via HOMER (hybrid optimization of multiple energy resources) a sensitivity analysis is conducted to ascertain the impact of ±10% fluctuations in wind speed solar radiation temperature and water velocity on annual electric production unmet electricity load LCOE (levelized cost of electricity) and NPC (net present cost). For this a far-off village with 15 households is selected as the case study. The results reveal that the NPC LCOE and LCOH (levelized cost of hydrogen) of the system are equal to $333074 0.1155 $/kWh and 4.59 $/kg respectively. Technical analysis indicates that the PV system with the rated capacity of 40 kW accounts for 43.7% of total electricity generation. This portion for the wind turbine and the hydrokinetic turbine with nominal capacities of 10 kW and 20 kW equates to 23.6% and 32.6% respectively. Finally the results of sensitivity assessment show that among the four variables only a +10% fluctuation in water velocity causes a 20% decline in NPC and LCOE.

In this study a techno-economic analysis tool for conducting detailed feasibility studies on the deployment of green hydrogen hubs for fuel cell bus fleets is developed. The study evaluates and compares five green hydrogen hub configurations’ operational and economic performance under a typical metropolitan bus fleet refuelling schedule. Each configuration differs based on its electricity sourcing characteristics such as the mix of energy sources capacity sizing financial structure and grid interaction. A detailed comparative analysis of distinct green hydrogen hub configurations for decarbonising a fleet of fuel-cell buses is conducted. Among the key findings is that a hybrid renewable electricity source and hydrogen storage are essential for cost-optimal operation across all configurations. Furthermore bi-directional grid-interactive configurations are the most costefficient and can benefit the electricity grid by flattening the duck curve. Lastly the paper highlights the potential for cost reduction when the fleet refuelling schedule is co-optimized with the green hydrogen hub electricity supply configuration.

Underground hydrogen storage (UHS) in salt caverns is a sustainable energy solution to reduce global warming. Salt rocks provide an exceptional insulator to store natural hydrogen as they have low porosity and permeability. Nevertheless the salt creeping nature and hydrogeninduced impact on the operational infrastructure threaten the integrity of the injection/production wells. Furthermore the scarcity of global UHS initiatives indicates that investigations on well integrity remain insufficient. This study strives to profoundly detect the research gap and imperative considerations for well integrity preservation in UHS projects. The research integrates the salt critical characteristics the geomechanical and geochemical risks and the necessary measurements to maintain well integrity. The casing mechanical failure was found as the most challenging threat. Furthermore the corrosive and erosive effects of hydrogen atoms on cement and casing may critically put the well integrity at risk. The research also indicated that the simultaneous impact of temperature on the salt creep behavior and hydrogen-induced corrosion is an unexplored area that has scope for further research. This inclusive research is an up-to-date source for analysis of the previous advancements current shortcomings and future requirements to preserve well integrity in UHS initiatives implemented within salt caverns.

To meet environmental goals while maintaining economic competitiveness worldwide ports have increased the amount of renewable energy production and have focused in optimizing performances and energy efficiency. However carbon-neutral operation of industrial port areas (IPA) is challenging and requires the decarbonization of industrial processes and heavy transport systems. This study proposes a comprehensive review of decarbon ization strategies for IPA with a particular focus on the role that green hydrogen could play when used as renewable energy carrier. Much information on existing and future technologies was also derived from the analysis of 74 projects (existing and planned) in 36 IPAs 80 % of which are in Europe concerning hydrogenbased decarbonization strategies. The overall review shows that engine operation of ships at berth are respon sible of more than 70 % of emissions in ports. Therefore onshore power supply (OPS) seems to be one of the main strategies to reduce port pollution. Nevertheless OPS powered by hydrogen is not today easily achievable. By overcoming the current cost-related and regulation barriers hydrogen can also be used for the import/export of green energy and the decarbonization of hard-to-abate sectors. The technical and economic data regarding hydrogen-based technologies and strategies highlighted in this paper are useful for further research in the field of definition and development of decarbonization strategies in the IPA.

During the last two decades Gulf Cooperation Council (GCC) countries have seen their population economies and energy production growing steeply with a substantial increase in Gross Domestic Product. As a result of this growth GCC consumption-based carbon dioxide (CO2) emissions increased from 540.79 Metric tons of CO2 equivalent (MtCO2) in 2003 to 1090.93 MtCO2 in 2020. The assumptions and strategies that have driven energy production in the past are now being recast to achieve a more sustainable economic development. The aim of this study is to review and analyze ongoing energy transition strategies that characterize this change to identify challenges and opportunities for bolstering the effectiveness of current strategic orientations. The ensuing analysis shows that since COP26 GCC countries have been pursuing a transition away from carbon-based energy policies largely characterized by the adoption of solar PV with other emerging technologies including energy storage carbon capture and hydrogen generation and storage. While as of 2022 renewable energy adoption in the GCC only represented 0.15 % of global installed capacity GCC countries are making strong efforts to achieve their declared 2030 energy targets that average about 26 % with peaks of 50 % in Saudi Arabia and 30 % in the UAE and Oman. With reference to solar energy plans are afoot to add 42.1 GW of solar photovoltaics and concentrated solar power which will increase 8-fold the current installed renewable capacity (5.1 GW). At the same time oil and gas production rates remain stable and fossil fuel subsidies have grown in the last few years. Also there is a marked preference for the deployment of CCUS and utility-scale solar energy technology vs. distributed solar energy energy efficiency and nature-based solutions. The pursuit of energy transition in the GCC will require increased efforts in the latter and other overlooked strategic endeavors to achieve a more balanced portfolio of sustainable energy solutions with stronger emphasis on energy efficiency (as long as rebound effects are mitigated) and nature-based solutions. Increased efforts are also needed in promoting governance practices aimed to institutionalize regulatory frameworks incentives and cooperation activities that promote the reduction of fossil fuel subsidies and the transition away from fossil fuels.

Hydrogen Refueling Stations (HRS) are a key infrastructure to the successful deployment of hydrogen mobility. Their cost-effectiveness will represent an increasingly crucial issue considering the foreseen growth of vehicle fleets from few captive fleets to large-scale penetration of hydrogen vehicles. In this context a detailed component-oriented cost model is important to assess HRS costs for different design concepts layout schemes and possible customizations respect to aggregate tools which are mostly available in literature. In this work an improved version of a previously developed component-oriented scale-sensitive HRS cost model is applied to 5 different European HRS developed within the 3Emotion project with different refueling capacities (kgH2/day) hydrogen supply schemes (in-situ production or delivery) storage volumes and pressures and operational strategies. The model output allows to assess the upfront investment cost (CAPEX) the annual operational cost (OPEX) and the Levelized Cost of Hydrogen (LCOH) at the dispenser and identify the most crucial cost components. The results for the five analyzed HRS sites show an LCOH at the nozzle of around 8-9 €/kg for delivery based HRSs which are mainly dominated by the H2 retail price and transport service price and around 11-12 €/kg for on-site producing HRS for which the electrolyzer CAPEX and electricity price plays a key role in the cost structure. The compression storage and dispensing sections account for between 1-3 €/kg according to the specific design & performance requirements of the HRS. The total LCOH values are comparable with literature standard market prices for similar scale HRSs and with the 3Emotion project targets.

At scale biomass-based fuels are seen as long-term alternatives to conventional shipping fuels to reduce greenhouse gas emissions in the maritime sector. While the operational benefits of renewable methanol as a marine fuel are well-known its cost and environmental performance depend largely on production method and geographic context. In this study a techno-economic and environmental assessment of renewable methanol produced by gasification of forestry residues is performed. Two biorefinery systems are modeled thermody namically for the first time integrating several design changes to extend past work: (1) methanol synthesized by gasification of torrefied biomass while removing and storing underground a fraction of the carbon initially contained in it and (2) integration of a polymer electrolyte membrane (PEM) electrolyzer for increased carbon efficiency via hydrogen injection into the methanol synthesis process. The chosen use case is set in California with forest residue biomass as the feedstock and the ports of Los Angeles and Long Beach as the shipping fuel demand point. Methanol produced by both systems achieves substantial lifecycle greenhouse gas emissions savings compared to traditional shipping fuels ranging from 38 to 165% from biomass roadside to methanol combustion. Renewable methanol can be carbon-negative if the CO2 captured during the biomass conversion process is sequestered underground with net greenhouse gas emissions along the lifecycle amounting to − 57 gCO2eq/MJ. While the produced methanol in both pathways is still more expensive than conventional fossil fuels the introduction of CO2eq abatement incentives available in the U.S. and California could bring down minimum fuel selling prices substantially. The produced methanol can be competitive with fossil shipping fuels at credit amounts ranging from $150 to $300/tCO2eq depending on the eligible credits.

The use of green hydrogen as a high-energy fuel of the future may be an opportunity to balance the unstable energy system which still relies on renewable energy sources. This work is a comprehensive review of recent advancements in green hydrogen production. This review outlines the current energy consumption trends. It presents the tasks and challenges of the hydrogen economy towards green hydrogen including production purification transportation storage and conversion into electricity. This work presents the main types of water electrolyzers: alkaline electrolyzers proton exchange membrane electrolyzers solid oxide electrolyzers and anion exchange membrane electrolyzers. Despite the higher production costs of green hydrogen compared to grey hydrogen this review suggests that as renewable energy technologies become cheaper and more efficient the cost of green hydrogen is expected to decrease. The review highlights the need for cost-effective and efficient electrode materials for large-scale applications. It concludes by comparing the operating parameters and cost considerations of the different electrolyzer technologies. It sets targets for 2050 to improve the efficiency durability and scalability of electrolyzers. The review underscores the importance of ongoing research and development to address the limitations of current electrolyzer technology and to make green hydrogen production more competitive with fossil fuels.

Green hydrogen (GH2) is expected to play an important role in future energy systems in their fight against climate change. This study after briefly recalling how GH2 is produced and the main steps throughout its life cycle analyses its current development environmental and social impacts and a series of case studies from selected literature showing its main applications as fuel in transportation and electricity sectors as a heat producer in high energy intensive industries and residential and commercial buildings and as an industrial feedstock for the production of other chemical products. The results show that the use of GH2 in the three main areas of application has the potential of contributing to the decarbonization goals although its generation of non-negligible impacts in other environmental categories requires attention. However the integration of circular economy (CE) principles is important for the mitigation of these impacts. In social terms the complexity of the value chain of GH2 generates social impacts well beyond countries where GH2 is produced and used. This aspect makes the GH2 value chain complex and difficult to trace somewhat undermining its renewability claims as well as its expected localness that the CE model is centred around.

Electrolytic hydrogen from renewable sources is central to many nations' net-zero emission strategies serving as a low-carbon alternative for traditional uses and enabling decarbonisation across multiple sectors. Current stringent policies in the EU and US are set to soon require hourly time-matching of renewable electricity generation used by electrolysers aimed at ensuring that hydrogen production does not cause significant direct or indirect emissions. Whilst such requirements enhance the “green credentials” of hydrogen they also increase its production costs. A modest relaxation of these requirements offers a practicable route for scaling up low-carbon hydrogen production optimising both costs and emission reductions. Moreover in jurisdictions with credible and near-to-medium-term decarbonisation targets immediate production of electrolytic hydrogen utilising grid electricity would have a lifetime carbon intensity comparable to or even below blue hydrogen and very significantly less than that of diesel emphasising the need to prioritise rapid grid decarbonisation of the broader grid.

This paper examines the changes in the performance level and pollutant emissions of a combustion chamber for turbofan engines. Two different fuels are compared: a conventional liquid fuel of the JET-A (kerosene) class and a hydrogen-based gaseous fuel. A turbofan engine delivering a 70 kN thrust at cruise conditions and 375 kN thrust at takeoff is considered. The comparison is carried out by investigating the combustion pattern with different boundary conditions the latter assigned along a typical flight mission. The calculations rely on a combined approach with a preliminary lumped parameter estimation of the engine performance and thermodynamic properties under different flight conditions (i.e. take-off climbing and cruise) and a CFD-based combustion simulation employing as boundary conditions the outputs obtained from the 0-D computations. The results are discussed in terms of performance thermal properties distributions throughout the combustor and of pollutant concentration at the combustor outflow. The results demonstrate that replacing the JET-A fuel with hydrogen does not affect the overall engine performance significantly and stable and efficient combustion takes place inside the burner although a different temperature regime is observable causing a relevant increase in thermal NO emissions.

Biohydrogen a low-carbon footprint technology can play a significant role in decarbonizing the energy system. It uses existing infrastructure is easily transportable and produces no greenhouse gas emissions. Four technologies can be used to produce biohydrogen: photosynthetic biohydrogen dark fermentation (DF) photo-fermentation and microbial electrolysis cells (MECs). DF produces more biohydrogen and is flexible with organic substrates making it a sustainable method of waste repurposing. However low achievable biohydrogen yields are a common issue. To overcome this catalytic mechanisms including enzymatic systems such as [Fe-Fe]- and [Ni-Fe]-hydrogenases in DF and electroactive microbial consortia in MECs alongside advanced electrode catalysts which collectively surmount thermodynamic and kinetic constraints and the two stage system such as DF connection to photo-fermentation and anaerobic digestion (AD) to microbial electrolysis cells (MECs) have been investigated. MECs can generate biohydrogen at better yields by using sugars or organic acids and combining DF and MEC technologies could improve biohydrogen production. As such this review highlights the challenges and possible solutions for coupling DF–MEC while also offering knowledge regarding the technical and microbiological aspects.

The article discusses a regenerative heat exchange system for a solid oxide electrolyzer cell (SOEC) used in the production of green hydrogen. The heating system comprises four heat exchangers one condenser heat exchanger and a mixer evaporator. A pump and two throttle valves have been added to separate the hydrogen at an elevated steam condensation temperature. Assuming steady flow a thermodynamic analysis was performed to validate the design and to predict the main parameters of the heating system. Numerical optimization was then used to determine the optimal temperature distribution ensuring the lowest possible additional external energy requirement for the regenerative system. The proportions of energy gained through heat exchange were determined and their distribution analyzed. The calculated thermal efficiency of the regenerative system is 75% while its exergy efficiency is 73%. These results can be applied to optimize the design of heat exchangers for hydrogen production systems using SOECs.

Plastic waste continues to increasingly pollute the environment. Currently a significant portion of this waste is either landfilled or incinerated to generate energy which leads to substantial CO2 emissions. However thermochemical processing is a potential solution to create a circular economy with pyrolysis combined with the subsequent high-temperature treatment of the vapour-gas mixture being a method preferable to incineration. This study investigated the optimal conditions for the two-stage pyrolysis of non-recyclable plastic waste. The process involved a low-temperature treatment of feedstock followed by high-temperature exposure of the vapour-gas mixture in the presence of a carbon matrix. The final products of the two-stage pyrolysis were: synthesis gas mainly consisting of hydrogen and carbon monoxide; solid pyrolysis residue obtained in the first stage and high-carbon material during the second stage was obtained. The first stage of the two-stage pyrolysis was carried out at various temperatures ranging from 460 to 540 ◦C followed by cracking at 600 to 1000 ◦C with different ratios of packaging waste to wood charcoal (1:2 1:4 1:6). The conditions for obtaining more than 70 vol% hydrogen in the synthesis gas from packaging waste were determined the effect of changing the process parameters was studied. The decomposition kinetics of packaging waste showed activation energies of the first and second steps: 165 and 255 kJ/mol (Ozawa–Flynn–Wall method) 164 and 259 kJ/mol (Kissinger–Akahira–Sunose method) respectively. This work contributes to the study of efficient recycling methods for non-recyclable packaging waste and promotes advancements in sustainable waste management practices.

The successful commercialisation of underground hydrogen storage (UHS) is contingent upon technological readiness and social acceptance. A lack of social acceptance inadequate policies/regulations an unreliable business case and environmental uncertainty have the potential to delay or prevent UHS commercialisation even in cases where it is ready. The technologies utilised for underground hydrogen and carbon dioxide storage are analogous. The differences lie in the types of gases stored and the purpose of their storage. It is anticipated that the challenges related to public acceptance will be analogous in both cases. An assessment was made of the possibility of transferring experiences related to the social acceptance of CO2 sequestration to UHS based on an analysis of relevant articles from indexed journals. The analysis enabled the identification of elements that can be used and incorporated into the social acceptance of UHS. A framework was identified that supports the assessment and implementation of factors determining social acceptance ranging from conception to demonstration to implementation. These factors include education communication stakeholder involvement risk assessment policy and regulation public trust benefits research and demonstration programmes and social embedding. Implementing these measures has the potential to increase acceptance and facilitate faster implementation of this technology.

Harnessing surplus wind and solar energy for water electrolysis boosts the efficiency of renewable energy utilization and supports the development of a low-carbon energy framework. However the intermittent and unpredictable nature of wind and solar power generation poses significant challenges to the dynamic stability and hydrogen production efficiency of electrolyzers. This study introduces a multi-state rotational control strategy for a hybrid electrolyzer system designed to produce hydrogen. Through a detailed examination of the interplay between electrolyzer power and efficiency—along with operational factors such as load range and startup/shutdown times—six distinct operational states are categorized under three modes. Taking into account the differing dynamic response characteristics of proton exchange membrane electrolyzers (PEMEL) and alkaline electrolyzers (AEL) a power-matching mechanism is developed to optimize the performance of these two electrolyzer types under varied and complex conditions. This mechanism facilitates coordinated scheduling and seamless transitions between operational states within the hybrid system. Simulation results demonstrate that compared to the traditional sequential startup and shutdown approach the proposed strategy increases hydrogen production by 10.73% for the same input power. Moreover it reduces the standard deviation and coefficient of variation in operating duration under rated conditions by 27.71 min and 47.04 respectively thereby enhancing both hydrogen production efficiency and the dynamic operational stability of the electrolyzer cluster.

To address the challenges in wind power fluctuation smoothing using electrochemical-hydrogen hybrid energy storage a SOC self-recovery-based capacity optimization is proposed. The key issues include extreme high/low SOC states of electrochemical storage due to large charge-discharge disparities and the degradation of hydrogen storage tank SOH caused by its efficiency characteristics which lead to high configuration costs. First considering grid-connection lag time and algorithm adaptability an adaptive weighted filter is designed to suppress wind power fluctuations to obtain precise active power reference values for hybrid energy storage. The active power is then allocated between electrochemical and hydrogen storage using EMD and HT. Subsequently a complementary operation strategy for electrochemical-hydrogen systems is proposed which incorporates equivalent SOC metrics to assess the overall SOC level of electrochemical storage. By defining trigger thresholds for different operational modes abnormal SOC and SOH states are eliminated. Finally a full lifecycle economic cost assessment model based on the rainflow counting method is established to evaluate the impact of different threshold settings on the operational lifespan of energy storage and the overall configuration cost. The proposed method is validated through real-data simulations demonstrating its effectiveness in optimizing hybrid storage configurations and reducing costs compared to conventional strategies.

Solar energy is important for the future as it provides a clean renewable source of electricity that can help combat climate change by reducing reliance on fossil fuels via implementing various solar-based energy systems. In this study a unique configuration for a parabolic-trough-based solar system is presented that allows energy storage for periods of time with insufficient solar radiation. This model based on extensive analysis in MATLAB utilizing real-time weather data demonstrates promising results with strong practical applicability. An organic Rankine cycle with a regenerative configuration is applied to produce electricity which is further utilized for hydrogen generation. A proton exchange membrane electrolysis (PEME) unit converts electricity to hydrogen a clean and versatile energy carrier since the electricity is solar based. To harness the maximum value from this system additional energy during peak times is used to produce clean water utilizing a reverse osmosis (RO) desalination unit. The system’s performance is examined by conducting a case study for the city of Antalya Turkey to attest to the unit’s credibility and performance. This system is also optimized via the Grey Wolf multi-objective algorithm from energy exergy and techno-economic perspectives. For the optimization scenario performed the energy and exergy efficiencies of the system and the levelized cost of products are found to be approximately 26.5% 28.5% and 0.106 $/kWh respectively.

Hydrogen is a key energy carrier playing a vital role in sustainable energy systems. This review provides a comparative analysis of physical chemical and innovative hydrogen storage methods from technical environmental and economic perspectives. It has been identified that compressed and liquefied hydrogen are predominantly utilized in transportation applications while chemical transport is mainly supported by liquid organic hydrogen carriers (LOHC) and ammonia-based systems. Although metal hydrides and nanomaterials offer high hydrogen storage capacities they face limitations related to cost and thermal management. Furthermore artificial intelligence (AI)- and machine learning (ML)-based optimization techniques are highlighted for their potential to enhance energy efficiency and improve system performance. In conclusion for hydrogen storage systems to achieve broader applicability it is recommended that integrated approaches be adopted—focusing on innovative material development economic feasibility and environmental sustainability

The shipping industry faces the dual challenge of reducing emissions to meet net-zero targets by 2050 and transporting green energy sources like hydrogen and its derivatives. Green shipping corridors provide experimental routes for lowcarbon solutions with the Suez Canal uniquely positioned to lead. This paper examines the canal’s evolving role as a dynamic energy space where diverse actors and networks intersect shaping spatial power relations and aligning with green capitalism interests. It explores the Suez Canal’s potential to serve as a model for hydrogen initiatives and its capacity to influence global energy governance and geopolitical dynamics in the transition to a sustainable shipping future. The canal also represents a microcosm of broader global shifts toward a future hydrogen economy where numerous stakeholders vie for power and influence.

This study focuses on arguably the most contentious choice of energy supply option available for decarbonizing general-purpose long-haul road freight: hydrogen. For operators infrastructure providers energy providers and vehicle manufacturers to make the investments necessary to enable this transition it is essential to evaluate the feasibility of individual energy supply choices. A literature review is conducted identifying ten requirements for an energy supply choice to be feasible which are then translated into “what would need to be true” conditions for hydrogen to meet these requirements. Considering these evidence from literature is used to assess the likelihood of each condition becoming true within the lifespan of a vehicle bought today. It is concluded that it is unlikely that hydrogen will become feasible in this time frame meaning it can be disregarded as a current vehicle purchase consideration as it will not undermine the competitiveness or resale value of a vehicle using a different energy source bought today. There are two principal innovations in the study approach: the consideration of socio-technical and political as well as techno-economic factors; and the application of realist retroductive option assessment. While not necessary to address the research question regarding hydrogen a realist retroductive assessment is also presented for other prominent low carbon energy source options: battery electric electric road systems (ERS) and biofuels; and the conditions under which these options could be feasible are considered.

Cruise ship decarbonisation was studied on a Mediterranean cruise profile. The analysis focused on ship energy flows fuel consumption carbon emissions ship CII and EEDI. A combination of technologies for reducing ship fuel consumption was simulated before introducing hydrogen fueled machinery for the ship. The studied technologies included ultrasound antifouling shore power battery hybrid machinery waste heat recovery and air lubrication. Their application on the selected operational profile led to combined fuel savings of 187%. When the same technologies were combined to a hydrogen machinery the ship total energy consumption compared to baseline was reduced by 25%. The cause of this was the synergies in the ship energy system such as ship auxiliary powers heat consumption and machinery efficiency. The proposed methodology of ship energy analysis is important step in starting to evaluate new fuels for ships and in preliminary technology screening prior to integrating them in the ship design.

The world is experiencing the effects of climate change at an increasing rate including rising average global temperature caused primarily by greenhouse gas (GHG) emissions. Energy-intensive industries (EIIs) are major contributors to greenhouse gas emissions. The pulp and paper industry (PPI) is among the top five most energyintensive industries and it accounts for approximately 6 % of global industrial energy use and 2 % of direct industrial CO2 emissions. Therefore it is important to decarbonize this industrial sector to achieve the climate policy goal of achieving net-zero emissions as per the Paris Agreement. This paper presents a comprehensive review of the decarbonization options also known as decarbonization pathways for the pulp and paper industrial sector. These pathways are selected from available literature and they mainly include energy efficiency measures (EEMs) paper recycling switching to carbon-neutral fuels such as biomass and hydrogen electrification of heat supply and carbon capture & storage (CCS) among other emerging technologies. After identifying each decarbonization pathway is discussed in detail with its drivers and barriers to implementation. The Analytical Hierarchy Process AHP a multi-criteria decision-making MCDM technique is carried out to rank the decarbonization pathways on five distinct criteria: cost emission reduction potential technological readiness level (TRL) implementation time and scalability. The ranking is carried out in four distinct criteria weight regimes to present clear choices on different criterion weights. This review paper aims to add to the existing literature to provide clear indications in choosing the pathways toward the decarbonization effort in the pulp & paper industry under various strategic priorities.

We combine state-of-the-art thermo-metallurgical welding process modeling with coupled diffusion-elastic– plastic phase field fracture simulations to predict the failure states of hydrogen transport pipelines. This enables quantitatively resolving residual stress states and the role of brittle hard regions of the weld such as the heat affected zone (HAZ). Failure pressures can be efficiently quantified as a function of asset state (existing defects) materials and weld procedures adopted and hydrogen purity. Importantly simulations spanning numerous relevant conditions (defect size and orientations) are used to build Virtual Failure Assessment Diagrams (FADs) enabling a straightforward uptake of this mechanistic approach in fitness-for-service assessment. Model predictions are in very good agreement with FAD approaches from the standards but show that the latter are not conservative when resolving the heterogeneous nature of the weld microstructure. Appropriate mechanistic FAD safety factors are established that account for the role of residual stresses and hard brittle weld regions.