Cyprus

This review paper examines the key barriers to using green ammonia as an alternative fuel in maritime industry. A literature survey is performed based on research articles and grey literature with the aim of discussing the technoeconomic problems with and benefits of ammonia and the relevant technologies. The limitations of ammonia as a maritime fuel and its supply chain the expected percentage demand by 2030 and 2050 its economic performance compared to other shipping fuels such as hydrogen and the current regulations that may impact ammonia as a maritime fuel are discussed. There are several key barriers to ammonia’s wide adoption: (1) High production costs due to the high capital costs associated with ammonia’s supply chain; (2) availability specifically the limited geographical locations available for ammonia bunkering; (3) the challenge of ramping up current ammonia production; and (4) the development of ammonia-specific regulations addressing issues such as toxicity safety and storage. The general challenges involved with blue ammonia are the large energy penalty and associated operational costs and a lack of technical expertise on its use. Regardless of the origin for ammonia to be truly zero-carbon its whole lifecycle must be considered—a key challenge that will aid in the debate about whether ammonia holds promise as a zero-carbon maritime fuel.

Hydrogen constitutes the only carbon-free fuel that can be used for energy conversion producing water as the only by-product. With water being one of the most abundant and inexhaustible raw materials in the world and the required electricity input being provided by renewable resources the produced hydrogen via water electrolysis constitutes a green pathway towards sustainability. In this work a hybrid PV power-to-hydrogen storage and fuel cell system is proposed to satisfy the domestic load of a residential building. Identifying alkaline as a mandatory electrolysis technology the performance of alkaline electrolysis cells is assessed considering the inclusion of a two-switch buck-boost converter. Following a comprehensive formulation with respect to each distinguished system component the balance condition at DC and AC buses is determined. The proposed configuration is evaluated taking into account PV systems of different ratings namely 3 kW 5 kW and 7 kW. Based on actual data relating to both PV generation and domestic load for the year 2020 the obtained results from the annual simulations are compared with feed-in tariff and net-metering schemes. According to the results PV capacity firming is achieved creating great opportunities for autonomy enhancement not only for electricity but also in other energy sectors.

Global efforts towards de-carbonization give rise to remarkable energy challenges which include renewable energy penetration increase and intermediate energy carriers for a sustainable transition. In order to reduce the dependence on fossil fuels alternative sources are considered by commodities to satisfy their increasing electricity demand as a consequence of a rise in population and the quantity of residential appliances in forthcoming years. The near-term trends appear to be in fuel and emission reduction techniques through the integration of carbon capture and storage and more efficient energy carriers exploiting alternative energy sources such as natural gas and hydrogen. Formulating both the fuel consumption and emission released the obtained experimental results showed that the total production cost can be reduced by making use of natural gas for the transition towards 2035’s targets. Maximum profits will be achieved with hydrogen as the only fuel in modern power plants by 2050. In this way the lowest electricity production can be achieved as well as the elimination of carbon dioxide emissions. Since the integration of renewable energy resources in the sectors of electricity heating/cooling and transportation will continuously be increased alternative feedstocks can serve as primary inputs and contribute to production cost profits improved utilization factors and further environmental achievements.

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.

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.

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 decreasing costs of the clean technologies the balanced scales of the Sustainable Development Goal 7 targets e.g. energy equity (EE) energy security (ES) and environmental sustainability (EVS) are quickly changing. This fundamental balancing process is a key requirement for a net-zero future. Accordingly this research analyzes the regime-switching effect of Hydrogen economy as the green transition sharing economy and economic complexity as the complexity-based and geopolitical risks and energy prices as the geostrategy policies on the Goal 7 targets. To this end a Markov-switching panel vector autoregressive method with regime-heteroskedasticity is applied to study advancing the Goal 7 in the world's twenty-five large energy consumers during 2004–2020. Concerning the parameters and statistics of the model the results refer to the existence of two regimes associated with the Goal 7 corners called “upward and downward” regimes for EE and “slightly upward and sharply upward” regimes for ES and EVS. It is revealed that the vulnerability of EE and ES targets is considerably reduced when the regime switches to the dominant regime that is “downward” and “slightly upward” regimes respectively and that of the EVS target remains unaffected. Through the impulse-response analysis the findings denote that the first hypothesis of the efficiency of the Hydrogen economy in promoting the Goal 7 targets is insignificant. However the significant short-term and dynamic shock effects of the complexity-based and geostrategy policies on the Hydrogen economy are detected which will be a feasible alternative assessment in advancing the Goal 7. Further the complexity-based policies support the Goal 7 targets under different regimes especially in the short- and medium-term. Hence the second hypothesis regarding the effectiveness of the complexity-based policies in promoting Goal 7 targets is confirmed. The third hypothesis concerning the complexity of the impact of geostrategy policies on the Goal 7 targets is verified. Particularly the switching process towards the Goal 7 may not necessarily be restricted by the geopolitical risks. Moreover EE is supported through energy prices in the short-term under both regimes while they are non-conductive to promote ES and EVS through time. Accordingly the decision-makers should acknowledge adopting a regime-switching path forward for ensuring the time-varying balanced growth of the Goal 7 targets as the impact of the suggested policy instruments is asymmetric.