Production & Supply Chain

Current climate crisis makes the need for reducing carbon emissions more than evident. For this reason renewable energy sources are expected to play a fundamental role. However these sources are not controllable but depend on the weather conditions. Therefore green hydrogen (hydrogen produced from water electrolysis using renewable energies) is emerging as the key energy carrier to solve this problem. Although different properties of hydrogen have been widely studied some key aspects such as the water and energy footprint as well as the technological development and the regulatory framework of green hydrogen in different parts of the world have not been analysed in depth. This work performs a data-driven analysis of these three pillars: water and energy footprint technological maturity and regulatory framework of green hydrogen technology. Results will allow the evaluation of green hydrogen deployment both the current situation and expectations. Regarding the water footprint this is lower than that of other fossil fuels and competitive with other types of hydrogen while the energy footprint is higher than that of other fuels. Additionally results show that technological and regulatory framework for hydrogen is not fully developed and there is a great inequality in green hydrogen legislation in different regions of the world.

Plastics have become integral to modern life playing crucial roles in diverse industries such as agriculture electronics automotive packaging and construction. However their excessive use and inadequate management have had adverse environmental impacts posing threats to terrestrial and marine ecosystems. Consequently researchers are increasingly searching for more sustainable ways of managing plastic wastes. Pyrolysis a chemical recycling method holds promise for producing valuable fuel sustainably. This study explores the process of the pyrolysis of plastic and incorporates recent advancements. Additionally the study investigates the integration of reforming into the pyrolysis process to improve hydrogen production. Hydrogen a clean and eco-friendly fuel holds significance in transport engines power generation fuel cells and as a major commodity chemical. Key process parameters influencing the final products for pyrolysis and in-line reforming are evaluated. In light of fossil fuel depletion and climate change the pyrolysis and in-line reforming strategy for hydrogen production is anticipated to gain prominence in the future. Amongst the various strategies studied the pyrolysis and in-line steam reforming process is identified as the most effective method for optimising hydrogen production from plastic wastes.

The present study investigates the feasibility of coupling the intermittent electric power generation from a wind farm with alkaline electrolyzers to produce green hydrogen. A physically accurate model of commercial elec trolytic modules has been first developed accounting for conversion efficiency drop due to modules’ cool down effects of shutdowns due to the intermittence of wind power and voltage degradation over the working time frame. The model has been calibrated on real modules for which industrial data were available. Three com mercial module sizes have been considered i.e. 1 2 and 4 MW. As a second step the model has been coupled with historical power datasets coming from a real wind farm characterized by a nominal installed power of 13.8 MW. Finally the model was implemented within a sizing algorithm to find the best combination between the actual wind farm power output and the electrolyzer capacity to reach the lowest Levelized Cost Of Hydrogen (LCOH) possible. To this end realistic data for the capital cost of the whole system (wind farm and electrolyzers) have been considered based on industrial data and market reports as well as maintenance costs including both periodic replacements of degraded components and periodic maintenance. Simulations showed that if the right sizing of the two systems is made competitive hydrogen production costs can be achieved even with current technologies. Bigger modules are less flexible but by now considerably cheaper than smaller ones. A future economy of scale in alkaline electrolyzers is then needed to foster the diffusion of the technology.

The increase in industrial production and energy consumption has led to excessive exploitation of non-renewable resources resulting in serious environmental problems such as greenhouse gas emissions. In response there’s a growing investment in renewable energies such as hydroelectric wind and solar power. However these sources are unable to fully meet demand leading to imbalances between consumption and production. An emerging solution to this challenge is green hydrogen produced from clean sources reducing dependence on fossil fuels and mitigating greenhouse gas emissions. The S-LCA methodology presented in the UNEP/SETAC Guidelines for the Social Life Cycle Assessment is applied to the production of green hydrogen via the electrolytic separation of water using a proton exchange electrolyser. The process involves the extraction and processing of raw materials from the electrolyser BOP and reverse osmosis system the manufacture of the systems and the production of green hydrogen. The data from each stage is inventoried and entered into the PSILCA v.3.1 and SHDB 2022FV5 databases integrated into the SimaPro software version 9.3.0.2 enabling a complete analysis of the social im pacts associated with the production of green hydrogen. The data was evaluated considering 4 stakeholder categories: workers value chain actors society and local community. The results indicate that the extraction and processing of raw materials for the electrolyser was the primary stage responsible for the social impacts in both databases. However the electrolyser manufacturing stage was the main contributor to the indicators “weekly working hours per employee” and “union density” in the PSILCA database. Nafion® and Iridium were identified as the major contributors among components in both databases. The study highlights the significant role played by countries like China and South Africa in social impacts particularly in the extraction and processing of raw materials. Despite this Portugal emerged as the largest contributor to five out of fourteen indicators in the PSILCA database while its contributions in the SHDB database were less than 7 %. Moreover a comparison between the two databases revealed that PSILCA exhibited a greater distribution of results across various stages components and countries assessed whereas SHDB showed more centralized results. The observed discrepancies between the results obtained from different databases can be attributed to three main factors: the input-output database utilized in each S-LCA tool the assumed risk levels for each indicator and the equivalence between indicators and subcategories. This exploratory study offers valuable insights for guiding strategic decisions regarding the social component of sustainability providing a detailed understanding of the social impacts associated with the specific case of green hydrogen production in a planned hub in Portugal.

Low-cost green hydrogen production will be key in reaching net zero carbon emissions by 2050. Green hydrogen can be produced by electrolysis using renewable energy including wind energy. However the configuration of offshore wind-to-hydrogen systems is not yet standardised. For example electrolysis can take place onshore or offshore. This work presents a framework to assess and quantify which configuration is more resilient so that security of hydrogen supply is incorporated in strategic decisions with the following key findings. First resilience should be assessed according to hydrogen supply rather than hydrogen production. This allows the framework to be applicable for all identified system configurations. Second resilience can be quantified according to the quantity ratio and lost revenue of the unsupplied hydrogen.

An energy source transition is necessary to realize carbon neutrality emphasizing the importance of a hydrogen economy. The transportation sector accounted for 27% of annual carbon emissions in 2019 highlighting the increasing importance of transitioning to hydrogen vehicles and establishing hydrogen refueling stations (HRSs). In particular HRSs need to be prioritized for deploying hydrogen vehicles and developing hydrogen supply chains. Thus research on HRS is important for achieving carbon neutrality in the transportation sector. In this study we improved the efficiency and scaled up the capacity of an on-site HRS (based on steam methane reforming with a hydrogen production rate of 30 Nm3/h) in Seoul Korea. This HRS was a prototype with low efficiency and capacity. Its efficiency was increased through thermodynamic analysis and heat exchanger network synthesis. Furthermore the process was scaled up from 30 Nm3/h to 150 Nm3/h to meet future hydrogen demand. The results of exergy analysis indicated that the exergy destruction in the reforming reactor and heat exchanger accounted for 58.1% and 19.8% respectively of the total exergy destruction. Thus the process was improved by modifying the heat exchanger network to reduce the exergy losses in these units. Consequently the thermal and exergy efficiencies were increased from 75.7% to 78.6% and from 68.1% to 70.4% respectively. The improved process was constructed and operated to demonstrate its performance. The operational and simulation data were similar within the acceptable error ranges. This study provides guidelines for the design and installation of low-carbon on-site HRSs.

As new sources of energy and advanced technologies are used there is a continuous evolution in energy supply demand and distribution. Advanced nuclear reactors and clean hydrogen have the opportunity to scale together and diversify the hydrogen production market away from fossil fuel-based production. Nevertheless the technical uncertainties surrounding nuclear hydrogen processes necessitate thorough research and a solid development effort. This paper aims to position pink hydrogen for nuclear hydrogen production at the forefront of sustainable energy-related solutions by offering a comprehensive review of recent advancements in nuclear hydrogen production covering both research endeavors and industrial applications. It delves into various pink hydrogen generation methodologies elucidating their respective merits and challenges. Furthermore this paper analyzes the evolving landscape of pink hydrogen in terms of its levelized cost by comparatively assessing different production pathways. By synthesizing insights from academic research and industrial practices this paper provides valuable perspectives for stakeholders involved in shaping the future of nuclear hydrogen production.

With a limited global carbon budget it is imperative that decarbonisation decisions are based on accurate holistic accounts of all greenhouse gas (GHG) emissions produced to assess their validity. Here the upstream GHG emissions of potential UK offshore Green and Blue hydrogen production are compared to GHG emissions from hydrogen produced through electrolysis using UK national grid electricity and the ‘business-as-usual’ case of continuing to combust methane. Based on an operational life of 25 years and producing 0.5MtH2 per year for each hydrogen process the results show that Blue hydrogen will emit between 200-262MtCO2e of GHG emissions depending on the carbon capture rates achieved (39%–90%) Green hydrogen produced via electrolysis using 100% renewable electricity from offshore wind will emit 20MtCO2e and hydrogen produced via electrolysis powered by the National Grid will emit between 103-168MtCO2e depending of the success of its NetZero strategy. The ‘business-as-usual’ case of continuing to combust methane releases 250MtCO2e over the same lifetime. This study finds that Blue hydrogen at scale is not compatible with the Paris Agreement reduces energy security and will require a substantial GHG emissions investment which excludes it from being a ‘low carbon technology’ and should not be considered for any decarbonisation strategies going forward.

Blue hydrogen is gaining attention as an intermediate step toward achieving eco-friendly green hydrogen production. However the general blue hydrogen production requires an energy-intensive process for carbon capture and storage resulting in low process efficiency. Additionally the hydrogen production processes steam methane reforming (SMR) and electrolysis emits waste heat and byproduct oxygen respectively. To solve these problems this study proposes an oxy-fuel combustion-based blue hydrogen production process that integrates fossil fuel-based hydrogen production and electrolysis processes. The proposed processes are SMR + SOEC and SMR + PEMEC whereas SMR solid oxide electrolysis cell (SOEC) and proton exchange membrane electrolysis cell (PEMEC) are also examined for comparison. In the proposed processes the oxygen produced by the electrolyzer is utilized for oxy-fuel combustion in the SMR process and the resulting flue gas containing CO2 and H2O is condensed to easily separate CO2. Additionally the waste heat from the SMR process is recovered to heat the feed water for the electrolyzer thereby maximizing the process efficiency. Techno-economic sensitivity and greenhouse gas (GHG) analyses were conducted to evaluate the efficiency and feasibility of the proposed processes. The results show that SMR + SOEC demonstrated the highest thermal efficiency (85.2%) and exergy efficiency (80.5%) exceeding the efficiency of the SMR process (78.4% and 70.4% for thermal and exergy efficiencies respectively). Furthermore the SMR + SOEC process showed the lowest levelized cost of hydrogen of 6.21 USD/kgH2. Lastly the SMR + SOEC demonstrated the lowest life cycle GHG emissions. In conclusion the proposed SMR + SOEC process is expected to be a suitable technology for the transition from gray to green hydrogen.

Hydrogen production from sunlight using innovative photocatalytic and photoelectrochemical systems offers decentralized sustainable energy solutions with potential applications in remote off-grid locations.<br/>Photocatalytic hydrogen production has the potential to transform clean cooking by reducing dependency on wood and charcoal in low-resource settings addressing significant health and environmental challenges.<br/>Photocatalytic reactors could also be used to capture atmospheric carbon dioxide and perform artificial photosynthesis mimicking processes found in nature producing green energy molecules.