Greece

The global need for energy has risen sharply recently. A global shift to clean energy is urgently needed to avoid catastrophic climate impacts. Hydrogen (H2) has emerged as a potential alternative energy source with near-net-zero emissions. In the African continent for sustainable access to clean energy and the transition away from fossil fuels this paper presents a new approach through which waste energy can produce green hydrogen from biomass. Bio-based hydrogen employing organic waste and biomass is recommended using biological (anaerobic digestion and fermentation) processes for scalable cheaper and low-carbon hydrogen. By reviewing all methods for producing green hydrogen dark fermentation can be applied in developed and developing countries without putting pressure on natural resources such as freshwater and rare metals the primary feedstocks used in producing green hydrogen by electrolysis. It can be expanded to produce medium- and long-term green hydrogen without relying heavily on energy sources or building expensive infrastructure. Implementing the dark fermentation process can support poor communities in producing green hydrogen as an energy source regardless of political and tribal conflicts unlike other methods that require political stability. In addition this approach does not require the approval of new legislation. Such processes can ensure the minimization of waste and greenhouse gases. To achieve cost reduction in hydrogen production by 2030 governments should develop a strategy to expand the use of dark fermentation reactors and utilize hot water from various industrial processes (waste energy recovery from hot wastewater).

In terms of energy generation and consumption ships are autonomous isolated systems with power demands varying according to the type of ship: passenger or commercial. The power supply in modern ships is based on thermal engines-generators which use fossil fuels marine diesel oil (MDO) and liquefied natural gas (LNG). The continuous operation of thermal engines on ships during cruises results in increased emissions of polluting gases mainly CO/CO2 . The combination of renewable energy sources (REs) and triple-fuel diesel engines (TFDEs) can reduce CO/CO2 emissions resulting in a “greener” interaction between ships and the ecosystem. This work presents a new control method for balancing the power generation and the load demands of a ship equipped with TFDEs fuel cells (FCs) and REs based on a real and accurate model of a super-tanker and simulation of its operation in real cruise conditions. The new TFDE technology engines are capable of using different fuels (marine diesel oil heavy fuel oil and liquified natural gas) producing the power required for ship operation as well as using compositions of other fuels based on diesel aiming to reduce the polluting gases produced. The energy management system (EMS) of a ship is designed and implemented in the structure of a finite state machine (FSM) using the logical design of transitions from state to state. The results demonstrate that further reductions in fossil fuel consumption as well as CO2 emissions are possible if ship power generation is combined with FC units that consume hydrogen as fuel. The hydrogen is produced locally on the ship through electrolysis using the electric power generated by the on-board renewable energy sources (REs) using photovoltaic systems (PVs) and wind energy conversion turbines (WECs).

In the quest for a sustainable future energy-intensive industries (EIIs) stand at the forefront of Europe’s decarbonisation mission. Despite their significant emissions footprint the path to comprehensive decarbonisation remains elusive at EU and national levels. This study scrutinises key sectors such as non-ferrous metals steel cement lime chemicals fertilisers ceramics and glass. It maps out their current environmental impact and potential for mitigation through innovative strategies. The analysis spans across Spain Greece Germany and the Netherlands highlighting sector-specific ecosystems and the technological breakthroughs shaping them. It addresses the urgency for the industry-wide adoption of electrification the utilisation of green hydrogen biomass bio-based or synthetic fuels and the deployment of carbon capture utilisation and storage to ensure a smooth transition. Investment decisions in EIIs will depend on predictable economic and regulatory landscapes. This analysis discusses the risks associated with continued investment in high-emission technologies which may lead to premature decommissioning and significant economic repercussions. It presents a dichotomy: invest in climate-neutral technologies now or face the closure and offshoring of operations later with consequences for employment. This open discussion concludes that while the technology for near-complete climate neutrality in EIIs exists and is rapidly advancing the higher costs compared to conventional methods pose a significant barrier. Without the ability to pass these costs to consumers the adoption of such technologies is stifled. Therefore it calls for decisive political commitment to support the industry’s transition ensuring a greener more resilient future for Europe’s industrial backbone.

Nowadays with the need for clean and sustainable energy at its historical peak new equipment strategies and methods have to be developed to reduce environmental pollution. Drastic steps and measures have already been taken on a global scale. Renewable energy sources (RESs) are being installed with a growing rhythm in the power grids. Such installations and operations in power systems must also be economically viable over time to attract more investors thus creating a cycle where green energy e.g. green hydrogen production will be both environmentally friendly and economically beneficial. This work presents a management method for assessing wind–solar– hydrogen (H2 ) energy systems. To optimize component sizing and calculate the cost of the produced H2 the basic procedure of the whole management method includes chronological simulations and economic calculations. The proposed system consists of a wind turbine (WT) a photovoltaic (PV) unit an electrolyzer a compressor a storage tank a fuel cell (FC) and various power converters. The paper presents a case study of green hydrogen production on Sifnos Island in Greece through RES together with a scenario where hydrogen vehicle consumption and RES production are higher during the summer months. Hydrogen stations represent H2 demand. The proposed system is connected to the main power grid of the island to cover the load demand if the RES cannot do this. This study also includes a cost analysis due to the high investment costs. The levelized cost of energy (LCOE) and the cost of the produced H2 are calculated and some future simulations correlated with the main costs of the components of the proposed system are pointed out. The MATLAB language is used for all simulations.

Renewable hydrogen is a flexible and versatile energy vector that can facilitate the decarbonization of several sectors and simultaneously ease the stress on the electricity grids that are currently being saturated with intermittent renewable power. But hydrogen technologies are currently facing limitations related to existing infrastructure limitations available markets as well as production storage and distribution costs. These challenges will be gradually addressed through the establishment operation and scaling-up of hydrogen valleys. Hydrogen valleys are an important stepping stone towards the full-scale implementation of the hydrogen economy with the target to foster sustainability lower carbon emissions and derisk the associated hydrogen technologies. These hydrogen ecosystems integrate renewable energy sources efficient hydrogen production storage transportation technologies as well as diverse end-users within a defined geographical region. This study offers an overview of the hydrogen valleys concept analyzing the critical aspects of their design and the key segments that constitute the framework of a hydrogen valley. А holistic overview of the key characteristics of a hydrogen valley is provided whereas an overview of key on-going hydrogen valley projects is presented. This work underscores the importance of addressing challenges related to the integration of renewable energy sources into electricity grids as well as scale-up challenges associated with economic and market conditions society awareness and political decision-making.

Eco-design is an innovative design methodology that focuses on minimizing the environmental footprint of industries including aviation right from the conceptual and development stages. However rising industrial demand calls for a more comprehensive strategy wherein beyond environmental considerations competitiveness becomes a critical factor supported by additional pillars of sustainability such as economic viability circularity and social impact. By incorporating sustainability as a primary design driver at the initial design stages this study suggests a shift from eco-driven to sustainability-driven design approaches for aircraft components. This expanded strategy considers performance and safety goals environmental impact costs social factors and circular economy considerations. To provide the most sustainable design that balances all objectives these aspects are rigorously quantified and optimized during the design process. To efficiently prioritize different variables methods such as multi-criteria decision-making (MCDM) are employed and a sustainability index is developed in this framework to assess the overall sustainability of each design alternative. The most sustainable design configurations are then identified through an optimization process. A typical aircraft component namely a hat-stiffened panel is selected to demonstrate the proposed approach. The study highlights how effectively sustainability considerations can be integrated from the early stages of the design process by exploring diverse material combinations and geometric configurations. The findings indicate that the type of fuel used and the importance given to the sustainability pillars—which are ultimately determined by the particular requirements and goals of the user—have a significant impact on the sustainability outcome. When equal prioritization is given across the diverse dimensions of sustainability the most sustainable option appears to be the full thermoplastic component when kerosene is used. Conversely when hydrogen is considered the full aluminum component emerges as the most sustainable choice. This trend also holds when environmental impact is prioritized over the other aspects of sustainability. However when costs are prioritized the full thermoplastic component is the most sustainable option whether hydrogen or kerosene is used as the fuel in the use phase. This innovative approach enhances the overall sustainability of aircraft components emphasizing the importance and benefits of incorporating a broader range of sustainability factors at the conceptual and initial design phases.

Hydrogen as a zero-emission fuel produces only water when used in fuel cells making it a vital contributor to reducing greenhouse gas emissions across industries like transportation energy and manufacturing. Efficient hydrogen storage requires lightweight high-strength vessels capable of withstanding high pressures to ensure the safe and reliable delivery of clean energy for various applications. Type V composite pressure vessels (CPVs) have emerged as a preferred solution due to their superior properties thus this study aims to predict the performance of a Type V CPV by developing its numerical model and calculating numerical burst pressure (NBP). For the validation of the numerical model a Hydraulic Burst Pressure test is conducted to determine the experimental burst pressure (EBP). The comparative study between NBP and EBP shows that the numerical model provides an accurate prediction of the vessel’s performance under pressure including the identification of failure locations. These findings highlight the potential of the numerical model to streamline the development process reduce costs and accelerate the production of CPVs that are manufactured by prepreg hand layup process (PHLP) using carbon fiber/epoxy resin prepreg material.

Hydrogen is gaining attention due to its potential to address key challenges in the sectors of energy transportation and industry since it is a much cleaner energy source when compared to fossil fuels. The transportation of hydrogen from the point of its production to the point of use can be performed by road rail sea pipeline networks or a combination of the abovementioned. Being in the preliminary stage of hydrogen use the utilization of the already existing natural gas pipeline networks for hydrogen mixtures transportation has been suggested as an efficient means of expanding hydrogen infrastructure. Yet exploring this alternative major challenges such as the pre-existence of cracks in the pipelines and the effect of hydrogen embrittlement on the material of the pipelines exist. In this paper the macroscopic numerical modeling of pipeline segments with the use of the finite element method is performed. In more details the structural integrity of intact and damaged pipeline segments of different geometry and mechanical properties was estimated. The effect of the pipeline geometry and material has been investigated in terms of stress contours with and without the influence of hydrogen. The results suggest that the structural integrity of the pipeline segments is more compromised by pre-existing longitudinal cracks which might lead to an increase in the maximum value of equivalent Von Mises stress by up to four times depending on their length-tothickness ratio. This effect becomes more pronounced with the existence of hydrogen in the pipeline network.

This paper presents TwinP2G a software application for optimal planning of investments in power-to-gas (PtG) systems. TwinP2G provides simulation and optimization services for the techno-economic analysis of user-customized energy networks. The core of TwinP2G is based on power flow simulation; however it supports energy sector coupling including electricity green hydrogen natural gas and synthetic methane. The framework provides a user-friendly user interface (UI) suitable for various user roles including data scientists and energy experts using visualizations and metrics on the assessed investments. An identity and access management mechanism also serves the security and authorization needs of the framework. Finally TwinP2G revolutionizes the concept of data availability and data sharing by granting its users access to distributed energy datasets available in the EnerShare Data Space. These data are available to TwinP2G users for conducting their experiments and extracting useful insights on optimal PtG investments for the energy grid.