Croatia
Systematic Overview of Newly Available Technologies in the Green Maritime Sector
Jan 2023
Publication
The application of newly available technologies in the green maritime sector is difficult due to conflicting requirements and the inter-relation of different ecological technological and economical parameters. The governments incentivize radical reductions in harmful emissions as an overall priority. If the politics do not change the continuous implementation of stricter government regulations for reducing emissions will eventually result in the mandatory use of what we currently consider alternative fuels. Immediate application of radically different strategies would significantly increase the economic costs of maritime transport thus jeopardizing its greatest benefit: the transport of massive quantities of freight at the lowest cost. Increased maritime transport costs would immediately disrupt the global economy as seen recently during the COVID-19 pandemic. For this reason the industry has shifted towards a gradual decrease in emissions through the implementation of “better” transitional solutions until alternative fuels eventually become low-cost fuels. Since this topic is very broad and interdisciplinary our systematic overview gives insight into the state-of-the-art available technologies in green maritime transport with a focus on the following subjects: (i) alternative fuels; (ii) hybrid propulsion systems and hydrogen technologies; (iii) the benefits of digitalization in the maritime sector aimed at increasing vessel efficiency; (iv) hull drag reduction technologies; and (v) carbon capture technologies. This paper outlines the challenges advantages and disadvantages of their implementation. The results of this analysis elucidate the current technologies’ readiness levels and their expected development over the coming years.
Tautomeric Equilibrium of an Asymmetric β-Diketone in Halogen-Bonded Cocrystals with Perfluorinated Iodobenzenes
Jun 2021
Publication
In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state we have prepared a series of cocrystals derived from an asymmetric β-diketone benzoyl-4-pyridoylmethane (b4pm) as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (ipfb) 12- 13- and 14-diiodotetraflorobenzene (12tfib 13tfib and 14tfib) and 135-triiodo-246-trifluorobenzene (135titfb). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of b4pm in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable in vacuo than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone benzoyl-3-pyridoylmethane (b3pm); however all attempts were unsuccessful which is attributed to more effective crystal packing of b3pm isomer compared to b4pm which reduced the probability of cocrystal formation.
Holistic Energy Efficiency and Environmental Friendliness Model for Short-Sea Vessels with Alternative Power Systems Considering Realistic Fuel Pathways and Workloads
Apr 2022
Publication
Energy requirements push the shipping industry towards more energy-efficient ships while environmental regulations influence the development of environmentally friendly ships by replacing fossil fuels with alternatives. Current mathematical models for ship energy efficiency which set the analysis boundaries at the level of the ship power system are not able to consider alternative fuels as a powering option. In this paper the energy efficiency and emissions index are formulated for ships with alternative power systems considering three different impacts on the environment (global warming acidification and eutrophication) and realistic fuel pathways and workloads. Besides diesel applications of alternative powering options such as electricity methanol liquefied natural gas hydrogen and ammonia are considered. By extending the analysis boundaries from the ship power system to the complete fuel cycle it is possible to compare different ships within the considered fleet or a whole shipping sector from the viewpoint of energy efficiency and environmental friendliness. The applicability of the model is illustrated on the Croatian ro-ro passenger fleet. A technical measure of implementation of alternative fuels in combination with an operational measure of speed reduction results in an even greater emissions reduction and an increase in energy efficiency. Analysis of the impact of voluntary speed reduction for ships with different power systems resulted in the identification of the optimal combination of alternative fuel and speed reduction by a specific percentage from the ship design speed.
The Use of Metal Hydrides in Fuel Cell Applications
Feb 2017
Publication
This paper reviews state-of-the-art developments in hydrogen energy systems which integrate fuel cells with metal hydride-based hydrogen storage. The 187 reference papers included in this review provide an overview of all major publications in the field as well as recent work by several of the authors of the review. The review contains four parts. The first part gives an overview of the existing types of fuel cells and outlines the potential of using metal hydride stores as a source of hydrogen fuel. The second part of the review considers the suitability and optimisation of different metal hydrides based on their energy efficient thermal integration with fuel cells. The performances of metal hydrides are considered from the viewpoint of the reversible heat driven interaction of the metal hydrides with gaseous H2. Efficiencies of hydrogen and heat exchange in hydrogen stores to control H2 charge/discharge flow rates are the focus of the third section of the review and are considered together with metal hydride – fuel cell system integration issues and the corresponding engineering solutions. Finally the last section of the review describes specific hydrogen-fuelled systems presented in the available reference data.
Hydrolysis-Based Hydrogen Generation Investigation of Aluminium System Adding Low-Melting Metals
Mar 2021
Publication
In this age of human civilization there is a need for more efficient cleaner and renewable energy as opposed to that provided by nonrenewable sources such as coal and oil. In this sense hydrogen energy has been proven to be a better choice. In this paper a portable graphite crucible metal smelting furnace was used to prepare ten multi-element aluminum alloy ingots with different components. The microstructure and phase composition of the ingots and reaction products were analyzed by X-ray diffraction (XRD) scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The reaction was carried out in a constant temperature water bath furnace at 60°C and the hydrogen production performance of the multi-element aluminum alloys in different proportions was compared by the drainage gas collection method. The experimental results show that the as-cast microstructure of Al–Ga–In–Sn aluminum alloy is composed of a solid solution of Al and part of Ga and a second phase of In3Sn. After the hydrolysis reaction the products were dried at 150°C and then analyzed by XRD. The products were mainly composed of AlOOH and In3Sn. Alloys with different compositions react at the same hydrolysis temperature and the hydrogen production performance is related to the ratio of low-melting-point metal elements. By comparing two different ratios of Ga–In–Sn (GIS) the hydrogen production capacity and production rate when the ratio is 6:3:1 are generally higher than those when the ratio is 7:2:1. The second phase content affects the hydrogen production performance.
HYDRIDE4MOBILITY: An EU HORIZON 2020 Project on Hydrogen Powered Fuel Cell Utility Vehicles Using Metal Hydrides in Hydrogen Storage and Refuelling Systems
Feb 2021
Publication
Volodymyr A. Yartys,
Mykhaylo V. Lototskyy,
Vladimir Linkov,
Sivakumar Pasupathi,
Moegamat Wafeeq Davids,
Gojmir Radica,
Roman V. Denys,
Jon Eriksen,
José Bellosta von Colbe,
Klaus Taube,
Giovanni Capurso,
Martin Dornheim,
Fahmida Smith,
Delisile Mathebula,
Dana Swanepoel,
Suwarno Suwarno and
Ivan Tolj
The goal of the EU Horizon 2020 RISE project 778307 “Hydrogen fuelled utility vehicles and their support systems utilising metal hydrides” (HYDRIDE4MOBILITY) is in addressing critical issues towards a commercial implementation of hydrogen powered forklifts using metal hydride (MH) based hydrogen storage and PEM fuel cells together with the systems for their refuelling at industrial customers facilities. For these applications high specific weight of the metallic hydrides has an added value as it allows counterbalancing of a vehicle with no extra cost. Improving the rates of H2 charge/discharge in MH on the materials and system level simplification of the design and reducing the system cost together with improvement of the efficiency of system “MH store-FC” is in the focus of this work as a joint effort of consortium uniting academic teams and industrial partners from two EU and associated countries Member States (Norway Germany Croatia) and two partner countries (South Africa and Indonesia).<br/>The work within the project is focused on the validation of various efficient and cost-competitive solutions including (i) advanced MH materials for hydrogen storage and compression (ii) advanced MH containers characterised by improved charge-discharge dynamic performance and ability to be mass produced (iii) integrated hydrogen storage and compression/refuelling systems which are developed and tested together with PEM fuel cells during the collaborative efforts of the consortium.<br/>This article gives an overview of HYDRIDE4MOBILITY project focused on the results generated during its first phase (2017–2019).
Planning and Operational Aspects of Individual and Clustered Multi-Energy Microgrid Options
Feb 2022
Publication
With the restructuring of the power system household-level end users are becoming more prominent participants by integrating renewable energy sources and smart devices and becoming flexible prosumers. The use of microgrids is a way of aggregating local end users into a single entity and catering for the consumption needs of shareholders. Various microgrid architectures are the result of the local energy community following different decarbonisation strategies and are frequently not optimised in terms of size technology or other influential factors for energy systems. This paper discusses the operational and planning aspects of three different microgrid setups looking at them as individual market participants within a local electricity market. This kind of implementation enables mutual trade between microgrids without additional charges where they can provide flexibility and balance for one another. The developed models take into account multiple uncertainties arising from photovoltaic production day-ahead electricity prices and electricity load. A total number of nine case studies and sensitivity analyses are presented from daily operation to the annual planning perspective. The systematic study of different microgrid setups operational principles/goals and cooperation mechanisms provides a clear understanding of operational and planning benefits: the electrification strategy of decarbonising microgrids outperforms gas and hydrogen technologies by a significant margin. The value of coupling different types of multi-energy microgrids with the goal of joint market participation was not proven to be better on a yearly level compared to the operation of same technology-type microgrids. Additional analyses focus on introducing distribution and transmission fees to an MG cooperation model and allow us to come to the conclusion of there being a minor impact on the overall operation.
CO2 Emissions Reduction Measures for RO-RO Vessels on Non-Profitable Coastal Liner Passenger Transport
Jun 2021
Publication
Reducing CO2 emissions from ships in unprofitable coastline transport using electricity and hydrogen has potential for island development to improve transport and protect biodiversity and nature. New technologies are a challenge for shipping companies and their introduction should be accompanied by a system of state aid for alternative energy sources. The energy requirements of an electric ferry for a route of up to 6 km were considered as well as the amount of hydrogen needed to generate the electricity required to charge the ferry batteries to enable a state aid scheme. For a daily ferry operation a specific fuel consumption of 60.6 g/kWh of liquid hydrogen is required in the system fuel cell with a total of 342.69 kg of hydrogen. Compared to marine diesel the use of electric ferries leads to a reduction of CO2 emissions by up to 90% including significantly lower NOx Sox and particulate matter (PM) emissions and operating costs by up to 80%.
Simulation-Assisted Determination of the Start-Up Time of a Polymer Electrolyte Fuel Cell
Nov 2021
Publication
Fuel starvation is a major cause of anode corrosion in low temperature polymer electrolyte fuel cells. The fuel cell start-up is a critical step as hydrogen may not yet be evenly distributed in the active area leading to local starvation. The present work investigates the hydrogen distribution and risk for starvation during start-up and after nitrogen purge by extending an existing computational fluid dynamic model to capture transient behavior. The results of the numerical model are compared with detailed experimental analysis on a 25 cm2 triple serpentine flow field with good agreement in all aspects and a required time step size of 1 s. This is two to three orders of magnitude larger than the time steps used by other works resulting in reasonably quick calculation times (e.g. 3 min calculation time for 1 s of experimental testing time using a 2 million element mesh).
Introduction of Hydrogen in the Kosovo Transportation Sector
Oct 2022
Publication
Based on the energy strategy of the Republic of Kosovo from 2017–2026 the increase in the integration of renewable energy sources (RES) in the national energy system was aimed at. However the hydrogen potential was not mentioned. In this work a roadmap toward the introduction of hydrogen in the energy system with the main focus on the transportation sector through three phases is proposed. In the first phase (until 2024) the integration of hydrogen in the transportation sector produced via water electrolysis from the grid electricity with the increase of up to a 0.5% share of fuel cell vehicles is intended. In the second phase (2025–2030) the hydrogen integration in the transportation sector is increased by including renewable hydrogen where the share of fuel cell electric vehicles (FCEVs) will be around 4% while in the third phase (2031–2050) around an 8% share of FCEVs in the transportation was planned. The technical and environmental analysis of hydrogen integration is focused on both the impact of hydrogen in the decarbonization of the transportation sector and the energy system. To model the Kosovo energy system the hourly deterministic EnergyPLAN model was used. This research describes the methodology based on EnergyPLAN modeling that can be used for any energy system to provide a clear path of RES and hydrogen implementation needed to achieve a zero-emission goal which was also set by various other countries. The predicted decrease in GHG emissions from 8 Mt in the referent year 2017 amounts to 7 Mt at the end of the first phase 2024 and 4.4 Mt at the end of the second phase 2030 to achieve 0 Mt by 2050. In order to achieve it the required amount of hydrogen by 2030 resulted in 31840 kg/year and by 2050 around 89731 kg/year. The results show the concrete impact of hydrogen on transport system stabilization and its influence on greenhouse gas (GHG) emissions reduction.
Three-Stage Modeling Framework for Analyzing Islanding Capabilities of Decarbonized Energy Communities
May 2023
Publication
Contrary to microgrids (MGs) for which grid code or legislative support are lacking in the majority of cases energy communities (ECs) are one of the cornerstones of the energy transition backed up by the EU’s regulatory framework. The main difference is that unlike MGs ECs grow and develop organically through citizen involvement and investments in the existing low-voltage (LV) distribution networks. They are not planned and built from scratch as closed distribution systems that are independent of distribution system operator plans as assumed in the existing literature. An additional benefit of ECs could be the ability to transition into island mode contributing to the resilience of power networks. To this end this paper proposes a three-stage framework for analyzing the islanding capabilities of ECs. The framework is utilized to comprehensively assess and compare the islanding capabilities of ECs whose organic development is based upon three potential energy vectors: electricity gas and hydrogen. Detailed dynamic simulations clearly show that only fully electrified ECs inherently have adequate islanding capabilities without the need for curtailment or additional investments.
Color-Coded Hydrogen: Production and Storage in Maritime Sector
Dec 2022
Publication
To reduce pollution from ships in coastal and international navigation shipping companies are turning to various technological solutions mostly based on electrification and the use of alternative fuels with a lower carbon footprint. One of the alternatives to traditional diesel fuel is the use of hydrogen as a fuel or hydrogen fuel cells as a power source. Their application on ships is still in the experimental phase and is limited to smaller ships which serve as a kind of platform for evaluating the applicability of different technological solutions. However the use of hydrogen on a large scale as a primary energy source on coastal and ocean-going vessels also requires an infrastructure for the production and safe storage of hydrogen. This paper provides an overview of color-based hydrogen classification as one of the main methods for describing hydrogen types based on currently available production technologies as well as the principles and safety aspects of hydrogen storage. The advantages and disadvantages of the production technologies with respect to their application in the maritime sector are discussed. Problems and obstacles that must be overcome for the successful use of hydrogen as a fuel on ships are also identified. The issues presented can be used to determine long-term indicators of the global warming potential of using hydrogen as a fuel in the shipping industry and to select an appropriate cost-effective and environmentally sustainable production and storage method in light of the technological capabilities and resources of a particular area.
Can Hydrogen Production Be Economically Viable on the Existing Gas-Fired Power Plant Location? New Empirical Evidence
Apr 2023
Publication
The paper provides an economic model for the assessment of hydrogen production at the site of an existing thermal power plant which is then integrated into the existing gas grid. The model uses projections of electricity prices natural gas prices and CO2 prices as well as estimates of the cost of building a power-to-gas system for a 25-year period. The objective of this research is to calculate the yellow hydrogen production price for each lifetime year of the Power-to-gas system to evaluate yellow hydrogen competitiveness compared to the fossil alternatives. We test if an incentive scheme is needed to make this technology economically viable. The research also provides several sensitivity scenarios of electricity natural gas and CO2 price changes. Our research results clearly prove that yellow hydrogen is not yet competitive with fossil alternatives and needs incentive mechanisms for the time being. At given natural gas and CO2 prices the incentive for hydrogen production needs to be 52.90 EUR/MWh in 2025 and 36.18 EUR/MWh in 2050. However the role of hydrogen in the green transition could be very important as it provides ancillary services and balances energy sources in the power system.
Alternative Power Options for Improvement of the Environmental Friendliness of Fishing Trawlers
Dec 2022
Publication
The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency environmental performance and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy i.e. by analyzing ship technical data and assuming its operative profile or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea including three phases of the Life-Cycle Assessment (manufacturing Well-to-Pump (WTP) and Pump-to-Wake (PTW)). Based on the data on fuel consumption the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy due to their high price and complex application in an obsolete fleet they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers.
Profitability Model of Green Hydrogen Production on an Existing Wind Power Plant Location
Feb 2024
Publication
This paper presents a new economic profitability model for a power-to-gas plant producing green hydrogen at the site of an existing wind power plant injected into the gas grid. The model is based on a 42 MW wind power plant for which an optimal electrolyzer of 10 MW was calculated based on the 2500 equivalent full load hours per year and the projection of electricity prices. The model is calculated on an hourly level for all variables of the 25 years of the model. With the calculated breakeven electricity price of 74.23 EUR/MWh and the price of green hydrogen production of 99.44 EUR/MWh in 2045 the wind power plant would produce 22410 MWh of green hydrogen from 31% of its total electricity production. Green hydrogen injected into the gas system would reduce the level of CO2 emissions by 4482 tons. However with the projected prices of natural gas and electricity the wind power plant would cover only 20% of the income generated by the electricity delivered to the grid by producing green hydrogen. By calculating different scenarios in the model the authors concluded that the introduction of a premium subsidy model is necessary to accelerate deployment of electrolyzers at the site of an existing wind power plant in order to increase the wind farm profitability.
Sustainable Energy Solutions: Utilising UGS for Hydrogen Production by Electrolysis
Jul 2024
Publication
Increasing the share of renewable energy sources (RESs) in the energy mix of countries is one of the main objectives of the energy transition in national economies which must be established on circular economy principles. In the natural gas storage in geological structures (UGSs) natural gas is stored in a gas reservoir at high reservoir pressure. During a withdrawal cycle the energy of the stored pressurised gas is irreversibly lost at the reduction station chokes. At the same time there is a huge amount of produced reservoir water which is waste and requires energy for underground disposal. The manuscript explores harnessing the exergy of the conventional UGS reduction process to generate electricity and produce hydrogen via electrolysis using reservoir-produced water. Such a model which utilises sustainable energy sources within a circular economy framework is the optimal approach to achieve a clean energy transition. Using an innovative integrated mathematical model based on real UGS production data the study evaluated the application of a turboexpander (TE) for electricity generation and hydrogen production during a single gas withdrawal cycle. The simulation results showed potential to produce 70 tonnes of hydrogen per UGS withdrawal cycle utilising 700 m3 of produced field water. The analysis showed that hydrogen production was sensitive to gas flow changes through the pressure reduction station underscoring the need for process optimisation to maximise hydrogen production. Furthermore the paper considered the categorisation of this hydrogen as “green” as it was produced from the energy of pressurised gas a carbon-free process.
Hydrogen Storage with Gravel and Pipes in Lakes and Reservoirs
Sep 2024
Publication
Climate change is projected to have substantial economic social and environmental impacts worldwide. Currently the leading solutions for hydrogen storage are in salt caverns and depleted natural gas reservoirs. However the required geological formations are limited to certain regions. To increase alternatives for hydrogen storage this paper proposes storing hydrogen in pipes filled with gravel in lakes hydropower and pumped hydro storage reservoirs. Hydrogen is insoluble in water non-toxic and does not threaten aquatic life. Results show the levelized cost of hydrogen storage to be 0.17 USD kg−1 at 200 m depth which is competitive with other large scale hydrogen storage options. Storing hydrogen in lakes hydropower and pumped hydro storage reservoirs increases the alternatives for storing hydrogen and might support the development of a hydrogen economy in the future. The global potential for hydrogen storage in reservoirs and lakes is 3 and 12 PWh respectively. Hydrogen storage in lakes and reservoirs can support the development of a hydrogen economy in the future by providing abundant and cheap hydrogen storage.
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