Greece
Expert Perceptions of Game-changing Innovations towards Net Zero
Dec 2022
Publication
Current technological improvements are yet to put the world on track to net-zero which will require the uptake of transformative low-carbon innovations to supplement mitigation efforts. However the role of such innovations is not yet fully understood; some of these ‘miracles’ are considered indispensable to Paris Agreement-compliant mitigation but their limitations availability and potential remain a source of debate. We evaluate such potentially game-changing innovations from the experts’ perspective aiming to support the design of realistic decarbonisation scenarios and better-informed net-zero policy strategies. In a worldwide survey 260 climate and energy experts assessed transformative innovations against their mitigation potential at-scale availability and/or widescale adoption and risk of delayed diffusion. Hierarchical clustering and multi-criteria decision-making revealed differences in perceptions of core technological innovations with next generation energy storage alternative building materials iron-ore electrolysis and hydrogen in steelmaking emerging as top priorities. Instead technologies highly represented in well-below-2◦C scenarios seemingly feature considerable and impactful delays hinting at the need to re-evaluate their role in future pathways. Experts’ assessments appear to converge more on the potential role of other disruptive innovations including lifestyle shifts and alternative economic models indicating the importance of scenarios including non-technological and demand-side innovations. To provide insights for expert elicitation processes we finally note caveats related to the level of representativeness among the 260 engaged experts the level of their expertise that may have varied across the examined innovations and the potential for subjective interpretation to which the employed linguistic scales may be prone to.
A Review on Experimental Studies Investigating the Effect of Hydrogen Supplementation in CI Diesel Engines—The Case of HYMAR
Aug 2022
Publication
Hydrogen supplementation in diesel Compression Ignition (CI) engines is gaining more attention since it is considered as a feasible solution to tackle the challenges that are related to the emission regulations that will be applied in the forthcoming years. Such a solution is very attractive because it requires only limited modifications to the existing technology of internal combustion CI engines. To this end numerous work on the investigation of an engine’s performance and the effects of emissions when hydrogen is supplied in the engine’s cylinders has been completed by researchers. However contradictory results were found among these studies regarding the efficiency of the engine and the emission characteristics achieved compared to the diesel-only operation. The different conclusions might be attributed to the different characteristics and technology level of the engines that were utilized as well as on the chosen operational parameters. This paper aims to present an overview of the experimental studies that have examined the effects of hydrogen addition in CI four-stroke diesel engines reporting the characteristics of the utilized engines the quantities of hydrogen tested the method of hydrogen induction used as well as the operational conditions tested in order to help interested researchers to easily identify relevant and appropriate studies to perform comparisons or validations by repeating certain cases. The presented data do not include any results or conclusions from these studies. Furthermore an experimental configuration along with the appropriate modifications on a heavy-duty auxiliary generator-set engine that was recently developed by the authors for the purposes of the HYMAR project is presented.
Hydrogen Role in the Valorization of Integrated Steelworks Process Off-gases through Methane and Methanol Syntheses
Jun 2021
Publication
The valorization of integrated steelworks process off-gases as feedstock for synthesizing methane and methanol is in line with European Green Deal challenges. However this target can be generally achieved only through process off-gases enrichment with hydrogen and use of cutting-edge syntheses reactors coupled to advanced control systems. These aspects are addressed in the RFCS project i3 upgrade and the central role of hydrogen was evident from the first stages of the project. First stationary scenario analyses showed that the required hydrogen amount is significant and existing renewable hydrogen production technologies are not ready to satisfy the demand in an economic perspective. The poor availability of low-cost green hydrogen as one of the main barriers for producing methane and methanol from process off-gases is further highlighted in the application of an ad-hoc developed dispatch controller for managing hydrogen intensified syntheses in integrated steelworks. The dispatch controller considers both economic and environmental impacts in the cost function and although significant environmental benefits are obtainable by exploiting process off-gases in the syntheses the current hydrogen costs highly affect the dispatch controller decisions. This underlines the need for big scale green hydrogen production processes and dedicated green markets for hydrogen-intensive industries which would ensure easy access to this fundamental gas paving the way for a C-lean and more sustainable steel production.
A Technology Review of Decarbonization: Efficient Techniques for Producing Hydrogen as Fuel
Aug 2023
Publication
Climate change is obvious in many ways. The weather changes rapidly from day to day reaching high temperatures such as 28 ◦C one day and heavy rain the next with temperatures below 18 ◦C. There are also very strong storms caused by this phenomenon. The way the environment acts is different than the current epoch would predict indicating a long-term shift in weather and temperature patterns. The mean temperature of earth is rising due to the greenhouse effect that is caused by human activity and mostly by the burning of fossil fuel emitting CO2 and other pollutant gasses. Nowadays every country is trying to lower CO2 emissions from everyday human activities a movement called “decarbonization”. Since the 18th century there has been a great deal of research carried out on possible alternatives to fossil fuels. Some of the work was just to discover ways to power heaters or automotive vehicle but there is a great deal of work remaining to complete regarding this issue after discovering the greenhouse effect and its impact on the planet’s climate in order to eliminate it by using fuel whose combustion emissions are more environmentally friendly. In the present work many discoveries will be presented that use hydrogen (H2 ) or hydroxy (H-OH) as fuel. The main reason for this is the emission of pure water after combustion but the most interesting part is the approach every scientist uses to create the fuel gas from water.
Discharge Modeling of Large Scale LH2 Experiments with an Engineering Tool
Sep 2021
Publication
Accurate estimation of mass flow rate and release conditions is important for the design of dispersion and combustion experiments for the subsequent validation of CFD codes/models for consequence assessment analysis within related risk assessment studies and for associated Regulation Codes and Standards development. This work focuses on the modelling of the discharge phase of the recent large scale LH2 release and dispersion experiments performed by HSE within the framework of PRESLHY project. The experimental conditions covered sub-cooled liquid stagnation conditions at two pressures (2 and 6 bara) and 3 release nozzle diameters (1 ½ and ¼ inches). The simulations were performed using a 1d engineering tool which accounts for discharge line effects due to friction extra resistance due to fittings and area change. The engineering tool uses the Possible Impossible Flow (PIF) algorithm for choked flow calculations and the Helmholtz Free Energy (HFE) EoS formulation. Three different phase distribution models were applied. The predictions are compared against measured and derived data from the experiments and recommendations are given both regarding engineering tool applicability and future experimental design.
Methanol, a Plugin Marine Fuel for Green House Gas Reduction—A Review
Jan 2024
Publication
The escalating global demand for goods transport via shipping has heightened energy consumption impacting worldwide health and the environment. To mitigate this international organizations aim to achieve complete fuel desulphurization and decarbonization by 50% by 2050. Investigating eco-friendly fuels is crucial particularly those with a reduced carbon and zero sulfur content. Methanol derived mainly from renewable sources and produced by carbon dioxide’s hydrogenation method stands out as an effective solution for GHG reduction. Leveraging its favorable properties global scalability and compatibility with the existing infrastructure especially LNGs methanol proves to be a cost-efficient and minimally disruptive alternative. This review explores methanol’s role as a hybrid maritime fuel emphasizing its ecological production methods advantages and challenges in the shipping industry’s green transition. It discusses the environmental impacts of methanol use and analyzes economic factors positioning methanol not only as an ecofriendly option but also as a financially prudent choice for global shipping. Methanol is efficient and cost-effective and excels over MGO especially in new ships. It is economically advantageous with decreasing investment costs compared to LNG while providing flexibility without specialized pressure tanks. Global marine fuel trends prioritize fuel traits accessibility and environmental considerations incorporating factors like policies emissions bunkering and engine adaptability during transitions.
Decarbonization of Former Lignite Regions with Renewable Hydrogen: The Western Macedonia Case
Oct 2023
Publication
For lignite intense regions such as the case of Western Macedonia (WM) the production and utilization of green hydrogen is one of the most viable ways to achieve near zero emissions in sectors like transport chemicals heat and energy production synthetic fuels etc. However the implementation of each technology that is available to a respective sector differs significantly in terms of readiness and the current installation scale of each technology. The goal of this study is the provision of a transition roadmap for a decarbonized future for the WM region through utilizing green hydrogen. The technologies which can take part in this transition are presented along with the implementation purpose of each technology and the reasonable extension that each technology could be adopted in the present context. The WM region’s limited capacity for green hydrogen production leads to certain integration scenarios with regards to the required hydrogen electrolyzer capacities and required power whereas an environmental assessment is also presented for each scenario.
A Detailed Parametric Analysis of a Solar-Powered Cogeneration System for Electricity and Hydrogen Production
Dec 2022
Publication
Hydrogen has received increased attention in the last decades as a green energy carrier and a promising future fuel. The integration of hydrogen as well as the development of cogeneration plants makes the energy sector more eco-friendly and sustainable. The aim of this paper is the investigation of a solar-fed cogeneration system that can produce power and compressed green hydrogen. The examined unit contains a parabolic trough collector solar field a thermal energy storage tank an organic Rankine cycle and a proton exchange membrane water electrolyzer. The installation also includes a hydrogen storage tank and a hydrogen compressor. The unit is analyzed parametrically in terms of thermodynamic performance and economic viability in steady-state conditions with a developed and accurate model. Taking into account the final results the overall energy efficiency is calculated at 14.03% the exergy efficiency at 14.94% and the hydrogen production rate at 0.205 kg/h. Finally the payback period and the net present value are determined at 9 years and 122 k€ respectively.
Integration of Different Storage Technologies towards Sustainable Development—A Case Study in a Greek Island
Mar 2024
Publication
The necessity for transitioning to renewable energy sources and the intermittent nature of the natural variables lead to the integration of storage units into these projects. In this research paper wind turbines and solar modules are combined with pumped hydro storage batteries and green hydrogen. Energy management strategies are described for five different scenarios of hybrid renewable energy systems based on single or hybrid storage technologies. The motivation is driven by grid stability issues and the limited access to fresh water in the Greek islands. A RES-based desalination unit is introduced into the hybrid system for access to low-cost fresh water. The comparison of single and hybrid storage methods the exploitation of seawater for the simultaneous fulfillment of water for domestic and agricultural purposes and the evaluation of different energy economic and environmental indices are the innovative aspects of this research work. The results show that pumped hydro storage systems can cover the energy and water demand at the minimum possible price 0.215 EUR/kWh and 1.257 EUR/m3 while hybrid storage technologies provide better results in the loss of load probability payback period and CO2 emissions. For the pumped hydro– hydrogen hybrid storage system these values are 21.40% 10.87 years and 2297 tn/year respectively.
A New Path towards Sustainable Energy Transition: Techno-Economic Feasibility of a Complete Hybrid Small Modular Reactor/Hydrogen (SMR/H2) Energy System
Oct 2023
Publication
Small modular reactors (SMRs) are nuclear reactors with a smaller capacity than traditional large-scale nuclear reactors offering advantages such as increased safety flexibility and cost-effectiveness. By producing zero carbon emissions SMRs represent an interesting alternative for the decarbonization of power grids. Additionally they present a promising solution for the production of hydrogen by providing large amounts of energy for the electrolysis of water (pink hydrogen). The above hint at the attractiveness of coupling SMRs with hydrogen production and consumption centers in order to form clusters of applications which use hydrogen as a fuel. This work showcases the techno-economic feasibility of the potential installation of an SMR system coupled with hydrogen production the case study being the island of Crete. The overall aim of this approach is the determination of the optimal technical characteristics of such a system as well as the estimation of the potential environmental benefits in terms of reduction of CO2 emissions. The aforementioned system which is also connected to the grid is designed to serve a portion of the electric load of the island while producing enough hydrogen to satisfy the needs of the nearby industries and hotels. The results of this work could provide an alternative sustainable approach on how a hydrogen economy which would interconnect and decarbonize several industrial sectors could be established on the island of Crete. The proposed systems achieve an LCOE between EUR 0.046/kWh and EUR 0.052/kWh while reducing carbon emissions by more than 5 million tons per year in certain cases.
Cost Projection of Global Green Hydrogen Production Scenarios
Nov 2023
Publication
A sustainable future hydrogen economy hinges on the development of green hydrogen and the shift away from grey hydrogen but this is highly reliant on reducing production costs which are currently too high for green hydrogen to be competitive. This study predicts the cost trajectory of alkaline and proton exchange membrane (PEM) electrolyzers based on ongoing research and development (R&D) scale effects and experiential learning consequently influencing the levelized cost of hydrogen (LCOH) projections. Electrolyzer capital costs are estimated to drop to 88 USD/kW for alkaline and 60 USD/kW for PEM under an optimistic scenario by 2050 or 388 USD/kW and 286 USD/kW respectively under a pessimistic scenario with PEM potentially dominating the market. Through a combination of declining electrolyzer costs and a levelized cost of electricity (LCOE) the global LCOH of green hydrogen is projected to fall below 5 USD/kgH2 for solar onshore and offshore wind energy sources under both scenarios by 2030. To facilitate a quicker transition the implementation of financial strategies such as additional revenue streams a hydrogen/carbon credit system and an oxygen one (a minimum retail price of 2 USD/kgO2 ) and regulations such as a carbon tax (minimum 100 USD/tonCO2 for 40 USD/MWh electricity) and a contract-for-difference scheme could be pivotal. These initiatives would act as financial catalysts accelerating the transition to a greener hydrogen economy.
Management of Hybrid Wind and Photovoltaic System Electrolyzer for Green Hydrogen Production and Storage in the Presence of a Small Fleet of Hydrogen Vehicles— An Economic Assessment
Dec 2023
Publication
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.
Multi-Physics Digital Model of an Aluminum 2219 Liquid Hydrogen Aircraft Tank
Feb 2024
Publication
Future liquid hydrogen-powered aircraft requires the design and optimization of a large number of systems and subsystems with cryogenic tanks being one of the largest and most critical. Considering previous space applications these tanks are usually stiffened by internal members such as stringers frames and stiffeners resulting in a complex geometry that leads to an eventual reduction in weight. Cryogenic tanks experience a variety of mechanical and thermal loading conditions and are usually constructed out of several different materials. The complexity of the geometry and the loads highlights the necessity for a computational tool in order to conduct analysis. In this direction the present work describes the development of a multi-physics finite element digital simulation conducting heat transfer and structural analysis in a fully parametric manner in order to be able to support the investigation of different design concepts materials geometries etc. The capabilities of the developed model are demonstrated by the design process of an independent-type aluminum 2219 cryogenic tank for commuter aircraft applications. The designed tank indicates a potential maximum take-off weight reduction of about 8% for the commuter category and demonstrates that aluminum alloys are serious candidate materials for future aircraft.
Literature Review of Hydrogen Energy Systems and Renewable Energy Sources
Nov 2023
Publication
The role of hydrogen as a clean energy source is a promising but also a contentious issue. The global energy production is currently characterized by an unprecedented shift to renewable energy sources (RES) and their technologies. However the local and environmental benefits of such RES-based technologies show a wide variety of technological maturity with a common mismatch to local RES stocks and actual utilization levels of RES exploitation. In this literature review the collected documents taken from the Scopus database using relevant keywords have been organized in homogeneous clusters and are accompanied by the registration of the relevant studies in the form of one figure and one table. In the second part of this review selected representations of typical hydrogen energy system (HES) installations in realistic in-field applications have been developed. Finally the main concerns challenges and future prospects of HES against a multi-parametric level of contributing determinants have been critically approached and creatively discussed. In addition key aspects and considerations of the HES-RES convergence are concluded.
The Interaction between Short- and Long-Term Energy Storage in an nZEB Office Building
Mar 2024
Publication
The establishment of near-autonomous micro-grids in commercial or public building complexes is gaining increasing popularity. Short-term storage capacity is provided by means of large battery installations or more often by the employees’ increasing use of electric vehicle batteries which are allowed to operate in bi-directional charging mode. In addition to the above short-term storage means a long-term storage medium is considered essential to the optimal operation of the building’s micro-grid. The most promising long-term energy storage carrier is hydrogen which is produced by standard electrolyzer units by exploiting the surplus electricity produced by photovoltaic installation due to the seasonal or weekly variation in a building’s electricity consumption. To this end a novel concept is studied in this paper. The details of the proposed concept are described in the context of a nearly Zero Energy Building (nZEB) and the associated micro-grid. The hydrogen produced is stored in a high-pressure tank to be used occasionally as fuel in an advanced technology hydrogen spark ignition engine which moves a synchronous generator. A size optimization study is carried out to determine the genset’s rating the electrolyzer units’ capacity and the tilt angle of the rooftop’s photovoltaic panels which minimize the building’s interaction with the external grid. The hydrogen-fueled genset engine is optimally sized to 40 kW (0.18 kW/kWp PV). The optimal tilt angle of the rooftop PV panels is 39◦ . The maximum capacity of the electrolyzer units is optimized to 72 kW (0.33 kWmax/kWp PV). The resulting system is tacitly assumed to integrate to an external hydrogen network to make up for the expected mismatches between hydrogen production and consumption. The significance of technology in addressing the current challenges in the field of energy storage and micro-grid optimization is discussed with an emphasis on its potential benefits. Moreover areas for further research are highlighted aiming to further advance sustainable energy solutions.
On Green Hydrogen Generation Technologies: A Bibliometric Review
Mar 2024
Publication
Green hydrogen produced by water electrolysis with renewable energy plays a crucial role in the revolution towards energy sustainability and it is considered a key source of clean energy and efficient storage. Its ability to address the intermittency of renewable sources and its potential to decarbonize sectors that are difficult to electrify make it a strategic component in climate change mitigation. By using a method based on a bibliometric review of scientific publications this paper represents a significant contribution to the emerging field of research on green hydrogen and provides a detailed review of electrolyzer technologies identifying key areas for future research and technology development. The results reflect the immaturity of a technology which advances with different technical advancements waiting to find the optimal technical solution that allows for its massive implementation as a source of green hydrogen generation. According to the results found in this article alkaline (ALK) and proton exchange membrane (PEM) electrolyzers seem to be the ones that interest the scientific community the most. Similarly in terms of regional analysis Europe is clearly committed to green hydrogen in view of the analysis of its scientific results on materials and electrolyzer capacity forecasts for 2030.
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