Spain

Given the urgent need to decarbonize the global energy system green hydrogen has emerged as a key alternative in the transition to renewables. However its production via electrolysis demands high water quality and raises environmental concerns particularly regarding reject water discharge. This study employs an experimental and analytical approach to define optimal water characteristics for electrolysis focusing on conductivity as a key parameter. A pilot water treatment plant with reverse osmosis and electrodeionization (EDI) was designed to simulate industrial-scale pretreatment. Twenty water samples from diverse natural sources (surface and groundwater) were tested selected for geographical and geological variability. A predictive algorithm was developed and validated to estimate useful versus reject water based on input quality. Three conductivity-based categories were defined: optimal (0–410 µS/cm) moderate (411–900 µS/cm) and restricted (>900 µS/cm). Results show that water quality significantly affects process efficiency energy use waste generation and operating costs. This work offers a technical and regulatory framework for assessing potential sites for green hydrogen plants recommending avoidance of high-conductivity sources. It also underscores the current regulatory gap regarding reject water treatment stressing the need for clear environmental guidelines to ensure project sustainability.

In this paper we aim to analyse the impact of hydrogen production decarbonisation and electrification scenarios on the infrastructure development generation mix CO2 emissions and system costs of the European power system considering the retrofit of the natural gas infrastructure. We define a reference scenario for the European power system in 2050 and use scenario variants to obtain additional insights by breaking down the effects of different assumptions. The scenarios were analysed using the European electricity market model COMPETES including a proposed formulation to consider retrofitting existing natural gas networks to transport hydrogen instead of methane. According to the results 60% of the EU’s hydrogen demand is electrified and approximately 30% of the total electricity demand will be to cover that hydrogen demand. The primary source of this electricity would be non-polluting technologies. Moreover hydrogen flexibility significantly increases variable renewable energy investment and production and reduces CO2 emissions. In contrast relying on only electricity transmission increases costs and CO2 emissions emphasising the importance of investing in an H2 network through retrofitting or new pipelines. In conclusion this paper shows that electrifying hydrogen is necessary and cost-effective to achieve the EU’s objective of reducing long-term emissions.

A viable green energy source for heavy industries and transportation is hydrogen. The internal combustion engine (ICE) when powered by hydrogen offers an economical and adaptable way to quickly decarbonize the transportation industry. In general two techniques are used to inject hydrogen into the ICE combustion chamber: port injection and direct injection. The present work examined direct injection technology highlighting the need to understand and manage hydrogen mixing within an ICE’s combustion chamber. Before combusting hydrogen it is critical to study its propagation and mixture behavior just immediately before burning. For this purpose the DI-CHG.2 direct injector model by BorgWarner was used. This injector operated at 35 barG and 20 barG as maximum and minimum upstream pressures respectively; a 5.8 g/s flow rate; and a maximum tip nozzle temperature of 250 ◦C. Experiments were performed using a high-pressure and hightemperature visualization vessel available at our facility. The combustion mixture prior to burning (spray) was visually controlled by the single-pass high-speed Schlieren technique. Images were used to study the spray penetration (S) and spray volume (V). Several parameters were considered to perform the experiments such as the injection pressure (Pinj) chamber temperature (Tch) and the injection energizing time (Tinj). With pressure ratio and injection time being the parameters commonly used in jet characterization the addition of temperature formed a more comprehensive group of parameters that should generally aid in the characterization of this type of gas jets as well as the understanding of the combined effect of the rate of injection on the overall outcome. It was observed that the increase in injection pressure (Pinj) increased the spray penetration depth and its calculated volume as well as the amount of mass injected inside the chamber according to the ROI results; furthermore it was also observed that with a pressure difference of 20 bar (the minimum required for the proper functioning of the injector used) cyclic variability increased. The variation in temperature inside the chamber had less of an impact on the spray shape and its penetration; instead it determined the velocity at which the spray reached its maximum length. In addition the injection energizing time had no effect on the spray penetration.

The current need to reduce carbon emissions makes hydrogen use essential for selfconsumption in microgrids. To make a profitability analysis of a microgrid the influence of equipment costs and the electricity price must be known. This paper studies the cost-effective electricity price (EUR/kWh) for a microgrid located at ‘’La Rábida Campus” (University of Huelva south of Spain) for two different energy-management systems (EMSs): hydrogen-priority strategy and batterypriority strategy. The profitability analysis is based on one hand on the hydrogen-systems’ cost reduction (%) and on the other hand considering renewable energy sources (RESs) and energy storage systems (ESSs) on cost reduction (%). Due to technological advances microgrid-element costs are expected to decrease over time; therefore future profitable electricity prices will be even lower. Results show a cost-effective electricity price ranging from 0.61 EUR/kWh to 0.16 EUR/kWh for hydrogen-priority EMSs and from 0.4 EUR/kWh to 0.17 EUR/kWh for battery-priority EMSs (0 and 100% hydrogen-system cost reduction respectively). These figures still decrease sharply if RES and ESS cost reductions are considered. In the current scenario of uncertainty in electricity prices the microgrid studied may become economically competitive in the near future

With renewable energy sources projected to become the dominant source of electricity hydrogen has emerged as a crucial energy carrier to mitigate their intermittency issues. Water electrolysis is the most developed alternative to generate green hydrogen so far. However in the past two decades steam electrolysis has attracted increasing interest and aims to become a key player in the portfolio of electrolytic hydrogen. In practice steam electrolysis follows two distinct operational approaches: Solid Oxide Electrolysis Cell (SOEC) and Proton Exchange Membrane (PEM) at high temperature. For both technologies this work analyses critical cell components outlining material characteristics and degradation issues. The influence of operational conditions on the performance and cell durability of both technologies is thoroughly reviewed. The analytical comparison of the two electrolysis alternatives underscores their distinct advantages and drawbacks highlighting their niche of applications: SOECs thrive in high temperature industries like steel production and nuclear power plants whereas PEM steam electrolysis suits lower temperature applications such as textile and paper. Being PEM steam electrolysis less explored this work ends up by suggesting research lines in the domain of i) cell components (membranes catalysts and gas diffusion layers) to optimize and scale the technology ii) integration strategies with renewable energies and iii) use of seawater as feedstock for green hydrogen production.

The member countries of the European Union (EU) have prioritized the incorporation of hydrogen as a key component of their energy objectives. As the world moves towards reducing its dependence on fossil fuels alternative sources of energy have gained prominence. With the growing development of Fuel Cell Electric Vehicles (FCEVs) the establishment of an infrastructure for hydrogen production and the creation of a network of service stations have become essential. This article’s purpose is to conduct a methodical review of literature regarding the use of green hydrogen for transportation and the planning of imperative infrastructure in the territory of the EU specifically Hydrogen Refueling Stations (HRS). In order to increase the acceptance of fuel cell vehicles a comprehensive network of hydrogen refueling stations (HRS) must be built that enable drivers to refuel their vehicles quickly and easily similar to gasoline or diesel vehicles. The literature review on this topic was conducted using the Web of Science database (WOS) with a variety of search terms proposed to cover all the key components of green hydrogen production and refueling infrastructure. The implementation of HRS powered by renewable energy sources is an important step in the adoption of fuel cell vehicles and overcoming the obstacles that come with their implementation will require cooperation and innovation from governments private businesses and other stakeholders.

During a severe accident in a nuclear power plant one of the potential threats to the containment is the occurrence of energetic combustion events. In modern plants Severe Accident Management Guidelines (SAMG) as well as dedicated mitigation hardware are in place to minimize/mitigate this combustion risk and thus avoid the release of radioactive material into the environment. Advancements in SAMGs are in the focus of AMHYCO an EU-funded Horizon 2020 project officially launched on October 1st 2020. The project consortium consists of 12 organizations (from six European countries and one from Canada) and is coordinated by the Universidad Politécnica de Madrid (UPM). The progress made in the first two years of the AMHYCO project is here presented. A comprehensive bibliographic review has been conducted providing a common foundation to build the knowledge gained during the project. After an extensive set of accident transients simulated both for phases occurring inside and outside the reactor pressure vessel a set of challenging sequences from the combustion risk perspective for different power plant types were identified. At the same time three generic containment models for the three considered reactor designs have been created to provide the full containment analysis simulations with lumped parameter models 3-dimensional containment codes and CFD codes. In order to further consolidate the model base combustion experiments and performance tests on passive auto-catalytic recombiners under explosion prone H2/CO atmospheres were performed at CNRS (France) and FZJ (Germany). Finally it is worth saying that the experimental data and engineering models generated from the AMHYCO project are useful for other industries outside the nuclear one.

Methane reforming is an interesting resource for obtaining hydrogen. DBD plasma-catalysis allows a direct use of electricity for methane reforming reactions such as direct methane reforming (MR) dry methane reforming (DMR) and steam methane reforming (SMR). In this work the first comprehensive comparison of these three routes for hydrogen production is experimentally and systematically investigated using dielectric barrier discharge (DBD) plasma and various catalyst formulations. Among the three routes SMR is the most effective achieving significantly higher methane conversion rates (24 %) and hydrogen content (80 %). DMR produces predominantly syngas mixture whereas MR yields hydrogen along with other light carbon compounds. In SMR route the favorable textural properties of Ni/Al2O3 are responsible for its high methane conversion rates while Ni/CeO2 increases hydrogen content since it favors the water-gas shift reaction especially at high power inputs. Therefore SMR using a suitable catalyst stands out as the most feasible reforming route for hydrogen production.

In recent years there has been a significant increase in the adoption of autonomous vehicles for marine and submarine missions. The advancement of emerging imaging navigation and communication technologies has greatly expanded the range of operational capabilities and opportunities available. The ENDURUNS project is a European research endeavor focused on identifying strategies for achieving minimal environmental impact. To measure these facts this article evaluates the product impacts employing the Life Cycle Assessment methodology for the first time following the ISO 14040 standard. In this analysis the quantitative values of Damage and Environmental Impact using the Eco-Indicator 99 methodology in SimaPro software are presented. The results report that the main contributors in environmental impact terms have been placed during the manufacturing phase. Thus one of the challenges is accomplished avoiding the use phase emissions that are the focus to reduce nowadays in the marine industry.

The transport sector is difficult to decarbonize due to its high reliance on fossil fuels accounting for 37% of global end-use sectors emissions in 2021. Therefore this work proposes an energy model to replace the Spanish vehicle fleet by hydrogen-fueled vehicles by 2050. Thus six regions are defined according to their proximity to regasification plants where hydrogen generation hubs are implemented. Likewise renewables deployment is subject to their land availability. Hydrogen is transported through an overhauled primary natural gas transport network while two distribution methods are compared for levelized cost of hydrogen minimization: gaseous pipeline vs liquid hydrogen supply in trucks. Hence a capacity of 443.1 GW of renewables 214 GW of electrolyzers and 3.45 TWh of hydrogen storage is required nationwide. Additionally gaseous hydrogen distribution is on average 17% cheaper than liquid hydrogen delivery. Finally all the regions present lower prices per km traveled than gasoline or diesel.