A Spatial Analysis of the Wind and Hydrogen Production in the Black Sea Basin

Abstract

The aim of the present work is to assess the wind and hydrogen production capacity of the Black Sea basin from a spatial point of view, by using reanalysis data that covers a 10-year interval (2015–2024). Based on the ERA5 data it was possible to highlight the general distribution of the wind resources at 100 m height, with more consistent resources being noticed in the region of the Azov Sea or in the north-western sector of the Black Sea, where average values of 8.3 m/s are expected. Taking into account that at this moment in the Black Sea area there are no operational offshore wind farms, several generators ranging from 3 to 15 MW were considered for assessment. In this case, from a single turbine, we can expect values in the range of 11.04 GWh (3 MW system) and 89 GWh (15 MW system), respectively. As a next step, the electricity generated from each wind turbine was used to highlight the hydrogen production of several electrolysers systems (or PEMs). The equivalent number of PEMs was identified, and in some cases it was noticed that some devices will not reach their full capacity, while for smaller PEMs a single 10 MW wind turbine could support the operation of almost four modules. Regarding hydrogen output, a maximum of 1560 tons/year can be expected from the PEMs connected to a 15 MW wind turbine.

1. Introduction

Alternative heat and power sources should proliferate as the average global temperature increases, and climate change becomes a more urgent concern. One of the main causes of the greenhouse effect is carbon emissions from the energy industry. Emissions of CO₂ were found to have increased by 0.8% in 2024, setting a new high of 37.8 Gt CO₂. Therefore, substituting renewable energy sources for fossil fuels might aid in keeping the global average temperature rise within the 1.5–2 °C range specified in the Paris Agreement [1].

Many nations now prioritize sustainable development, which calls for the rapid implementation of green energy alternatives. Different forms of renewable energy, including geothermal, biomass, wind, solar, and others, may be used as viable substitutes to manage and lower carbon emissions from fossil fuel-based energy systems. From a technological standpoint, renewable energy has grown significantly. For example, wind turbines have grown in size to produce significantly more power. Geothermal energy has also grown significantly through the development of enhanced geothermal systems (EGS) technology, which involves injecting water into rock formations to produce steam [2,3]. The utilization of renewable solar energy on water has gained popularity for freeing soils for agricultural purposes [4,5]. Consequently, just 32% (or 10 TWh) of the world’s energy output comes from renewable sources, this value being compared with 31.15 TWh of total energy generated in 2024.

However, since these sources are intermittent, the rate at which electricity is produced varies greatly based on a number of factors, including composition, location, and time of day [6]. Consequently, many approaches are being contemplated to address this challenge. For instance, power systems’ stability and dependability may be enhanced via hybrid energy systems that combine two or more energy sources [7]. On the other hand, demand-side response strategies, such as adjusting consumption patterns and enabling the direct use of renewable powecan help balance supply and demand. In order to make up for the mismatch between the system and the service, as well as between the source and the system, energy storage may also be very helpful. When it comes to air pollution and carbon emissions, wind energy is proven to be much more efficient than traditional fossil fuel-based energy sources. With onshore wind energy costing about $0.033/kWh and offshore wind energy costing about $0.075/kWh, wind energy has become economically competitive with fossil fuel energy, which has a weighted average cost of $0.100/kWh. This is undoubtedly less expensive than many other renewable sources [8]. The viability of wind resources in various parts of the globe has been the subject of several studies throughout the years [9,10,11,12,13,14,15,16]. Similar to other sources, studies have shown problems with the instability of the power provided by wind turbines (as it depends on wind flows) [17,18]. A subject of interest in this sector is how to store extra energy, such as in batteries or by creating hydrogen [19,20,21,22].

A clean secondary energy source, hydrogen has several benefits, including large supply, high calorific value, high energy density, storage, renewable energy, electricity and fuel, and zero pollution and carbon emissions [23]. For 2023, global hydrogen demand was 97 Mt [24]. The most common division of hydrogen is into three large categories, each of which is assigned a color. Thus, gray, blue and green are the basic colours [25]. There is also another division that also contains turquoise. Gray hydrogen is hydrogen derived from non-renewable sources. The production of ammonia and the refining of oil consume the majority of this hydrogen [26]. Similar to gray hydrogen, blue hydrogen is created by combining it with a process known as “Carbon Capture and Storage” (CCS) [27]. Since there are no greenhouse gas emissions, it is more ecologically benign and sustainable than gray hydrogen. “Green hydrogen”—the electrolysis of water using renewable energy sources like solar or wind. The majority of this hydrogen is produced using fossil fuels, with coal accounting for 23% and natural gas for 73%, the rest being obtained from other sources [28,29].

Because of its special qualities, hydrogen has the potential to power our society’s future energy model—known as the hydrogen economy—in conjunction with electricity [30]. It may really be a fully renewable fuel when derived from water or biomass. It can also be stored in a number of different forms, including gas, liquid, metal hydrides, or adsorbed under high pressure on appropriate porous substances [31]. It is readily transportable, effectively generated from, and transformed into power, and its usage as fuel has few adverse environmental consequences. Hydrogen can be obtained from wind energy through several electrolysis methods. These processes include Alkaline Water Electrolysis (AWE), anion exchange membrane electrolysis (AEM), proton exchange membrane electrolysis (PEM), high-temperature steam electrolysis (HTSE), solid oxide electrolysis (SOE) [32]. Of these, the most attractive is PEM, being capable of producing high-purity hydrogen in a rapid manner, but it also has a higher cost due to the catalysts made of precious materials.

As the idea of producing hydrogen from renewable sources becomes increasingly attractive, numerous studies in the literature evaluate this aspect. For instance, several studies have examined the feasibility of producing hydrogen using onshore wind energy. One such study is the one elaborated by Rezaei-Shouroki et al. [33] which employed a rectifier with a 95% efficiency rate to manufacture 21.9 tons of hydrogen annually in Iran using a 54–900 kW AWE wind turbine. Another research that employs onshore wind as a source of energy is the one made by Kien et al. [34] for a study in Vietnam. This time, a 1 MW Mitsubishi turbine is employed, and the optimal position yields 45.29 tons of hydrogen annually. Analogous research has been conducted for Saudi Arabia [35], yielding a maximum annual output of 367 tons of hydrogen. The study by Paulino de Azevedo et al. [36], which examined hydrogen production for Brazil, found that production of 100–700 tons/km²/year was possible due to the offshore field’s appeal for hydrogen production.

Research on PEM technology has focused on the integration of offshore energy for hydrogen production in regions like South China for a 400 MW farm [37], where productions of 23,800 tons of hydrogen annually have been documented, as well as on the coast of Ireland [38], where 510 MW farms have been shown to produce between 5000 and 14,000 tons of hydrogen annually. The Edirne-Enez coastline (Turkey) was also the subject of a similar investigation [39], although this time it only looked at a smaller farm with a capacity of around 16.5 MW, whose hydrogen production was measured at 131.81 kg/h. Studies on the generation of hydrogen and ammonia have also been conducted for the North Sea and the Baltic Sea [40]. In the case of hydrogen production utilizing a PEM type system, a production of 6880 tons was reported, using a 96 MW farm as a baseline. These studies reveal a growing interest and focused research effort in transforming offshore wind into hydrogen as a viable energy solution. Further research is needed to overcome existing technical and economic obstacles and unlock the full potential of this technology for a sustainable energy transition.

In the Black Sea, a large number of studies on marine renewable resources have been conducted. These examine wind speeds and wind power densities using historical data and reanalysis databases like ERA-Interim and ERA5 from the European Centre for Medium-Range Weather Forecasts (ECMWF) [41,42,43]. These simulations are conducted for the entire Black Sea region as well as for specific locations deemed to be of interest. Many studies are also concentrate on future investigations applying Regional Climate Models (RCM) [44,45,46]. Furthermore under evaluation are several kinds of renewable energy including wave and wind [47]. According to the reviewed literature, the Black Sea geographic characteristics make it a feasible location for a number of offshore wind projects, particularly in the northwest.

The novelty of this work lies in the fact that, for the first time, the Black Sea region is considered when estimating the amount of hydrogen that can be produced using electricity from offshore wind turbines as an input. The current work will be guided by the following research questions: (a) How much energy do offshore wind turbines in the Black Sea basin as a whole produce? (b) How many electrolysis systems are needed to convert all of the energy generated by wind turbines into hydrogen? (c) How much hydrogen can be produced by the electrolysis systems?

2. Materials and Methods

The European Centre for Medium-Range Weather Forecasts (ECMWF) is a non-governmental organization that has the support of 35 nations [48,49]. For the public as well as its members and partner nations, it generates global numerical weather forecasts and other data. An enhanced version of the ERA-Interim project, which was discontinued at the end of 2019, is the ERA5 dataset [50]. A new Integrated Forecast System model cycle (IFS Cycle 47r3) has been added to the reanalysis operations to significantly increase forecast accuracy and computational efficiency following years of advancements in modeling and data assimilation [51]. The ERA5 dataset offers estimates of many atmospheric, land surface, and sea state parameters on 0.25° × 0.25° latitude-longitude grids for every hour of the day [52]. Significant discrepancies may also arise when comparing data for specific in situ locations because the variables generated in this manner are linked to mean values that are influenced by the grid box and time step of a particular model [53].

The ERA5 data covers the interval from 1940 to present, being continuously updated and checked for errors in order to obtain a consistent source of historical data. The ERA5 is one reanalysis database that is frequently used by the researchers. This selection is made based on the fact that multiple meteorological parameters are available, being defined by extensive spatial and temporal coverage [54]. We need to keep in mind that these gridded data are defined by a spatial resolution of 0.25° (or 31 km), which means that the local effects cannot be captured precisely since there will be some uncertainties. Moreover, the accuracy of the ERA5 is limited in the case of the coastal areas that are defined by complex environmental conditions. It is considered that ERA5 is a suitable dataset for the assessment of long term patterns, with the mention that the absolute values may be biased [55,56].

ERA5 data were processed for hourly intervals (24 values per day) covering a 10-year period, from 2015 to 2024 considering the entire Black Sea area for which wind characteristics at an altitude of 100 m were obtained (U100).

For the present work, four different wind turbines will be considered for the wind energy evaluation, as shown in

Table 1. Technical parameters of the selected offshore wind turbines.

ID	Turbine	Hub Height (m)	Power Rating (MW)	Wind Speed (m/s)			Reference
				Cut-In	Rated	Cut-Out
T3	3 MW	100	3	3.00	14.00	25.00	[57]
T5	NREL 5 MW	90	5	3.00	11.40	25.00	[58]
T10	DTU-10 MW	119	10	4.00	11.40	25.00	[59]
T15	IEA 15 MW	150	15	3.00	10.59	25.00	[60]

and Figure 1. The four selected turbines cover a full spectrum of nominal capacity, starting from 3 MW and ending with the highest nominal power of 15 MW. All of these turbines are reference wind turbines, which provide an entry and educational point for understanding the fundamentals of design. Offshore wind energy has received more attention in recent years due to its increasingly advanced technologies. Since 2022–2023, offshore wind farms with turbines larger than 10 MW have been in operation.

The Seagreen Offshore Wind Farm, which uses 114 MHI Vestas V164-10 MW turbines, is an example of a farm that uses 10 MW turbines [61]. The EolMed Floating Wind Farm, another pilot offshore wind farm, is now under construction and is expected to be commissioned in 2025 [62]. The installation of 15 MW turbines began in 2024 when Vestas successfully installed the first V236-15.0 MW turbine. This was the first step toward the production phase for the installation of the first offshore wind turbine farm with such a potent model [63].

In the case of the electrolysis systems, four systems were selected based on their individual manufacturers and features which are presented in

Table 2. Details regarding the electrolysers systems according to [36].

ID	System	Production Capacity (kg/h)	Energy Consumption (kWh/kgH2)
PEM1	HyLYZER®—4.000-30	330.8	51.0
PEM2	HyLYZER®—1.000-30	82.7	52.0
PEM3	HyLYZER®—500-30	41.4	61.7
PEM4	SiLYZER 300	18.6	62.0

. We can see that the PEM1 system exhibits superior characteristics than the others, with a production capacity that is four times greater than that of PEM2 and roughly eighteen times greater than that of PEM4.

As can be noticed from Figure 2, the Black Sea is the area of interest of the study, for which 14 port cities were chosen as references. This is due to the fact that wind farm projects that transform their energy into hydrogen can be implemented in their immediate vicinity and within a coastal limit of 50 km, which creates the perfect setting for such projects.

The power curve for each wind turbine is unique and contains a number of important values, including cut-in, nominal, and cut-out wind speeds, for which the turbine performs differently, all of which are shown in Figure 1. According to Table 1, each turbine has a specific hub height ranging from 90 to 150 m, whereas the data extracted from the ERA5 database were at an altitude of 100 m. In order to adjust the initial wind speed for each hub height, a logarithmic wind profile formula will be utilized, as follows [64]:

$$U_{ref}=U_{ERA5}·{\displaystyle \frac{\mathrm{l}\mathrm{n}\left(z_{ref}\right)}{\mathrm{l}\mathrm{n}\left(z_0\right)}}/{\displaystyle \frac{\mathrm{l}\mathrm{n}\left(z_{ERA5}\right)}{\mathrm{l}\mathrm{n}\left(z_0\right)}}$$

(1)

where: $U_{ref}$ is the wind speed adjusted for each hub height, $U_{ERA5}$ represents the initial wind speed at 100 m ($z_{ERA5}$), while $z_0$—is the roughness factor (calm sea surface—0.0002 m) [65]. At this point, we can mention that the roughness length can increase to 0.001 m, corresponding to a rough sea [66]. Nevertheless, a calm sea surface value can be used for renewable analysis, this is the case of Balaguru et al. [67] for the evaluation of the wind resources related to the coastal area of India. Baki et al. [68] were focused on the Portuguese nearshore, highlighting at the same time that this value may not be appropriate for areas located close to the coastline. This work aims to provide an overall evaluation of the Black Sea wind potential and not to perform a sensitive analysis for a particular coastal environment or sea state.

A specific wind turbine’s Annual Electricity Production (AEP) can be calculated as follows [69]:

$$AEP=T\times {\int }_{cut-in}^{cut-out}f\left(U\right)P\left(U\right)dU$$

(2)

where: $T$ is the average number of hours per year, which is 8760 h/year, $cut-in$ and $cut-out$ refers to the turbine’s characteristics, $f\left(U\right)$ is the Weibull probability density function and $P\left(U\right)$ is a turbine’s power curve.

The amount of hydrogen produced by wind energy will be calculated using the following formula [35,70]:

$$M_H={\displaystyle \frac{AEP}{{ec}_{el}}}{\eta }_{el}$$

(3)

where $M_H$ is the amount of hydrogen generated in one year in $\mathrm{k}\mathrm{g}{\mathrm{H}}_2/\mathrm{y}\mathrm{e}\mathrm{a}\mathrm{r}$, $AEP$ is the Annual Electricity Production from the offshore wind, ${ec}_{el}$ is the electrolysis energy consumption, ${\eta }_{el}$ is the electrolysis efficiency and it ranges between 80 and 90%, for this study the adopted values is 90%.

In terms of the limitations of this work, we can mention: (a) concerning the precision of the results in determining the AEP due to the utilization of the ERA5 database with a resolution of 31 km; (b) the application of simplified equations for estimating hydrogen production; (c) hydrogen production is assessed statically, without consideration of storage alternatives.

3. Results and Discussions

The spatial distribution of the U100 parameter (average values) is provided in Figure 3. In this case, the wind speed varies between 1.19 and 8.32 m/s, much higher conditions being noticed in the vicinity of the Azov Sea or in the north-western part of the Black Sea. Much lower resources are accounted by the regions from the south-western part, especially the ones located near Batumi (Georgia). By looking at the 50 km isoline, we can notice that higher resources occur between this line and the coastline near Odessa, compared to the Romanian side where such values are visible from this line to the offshore areas. However, it is expected that in some cases the wind speed will increase with the distance from the shore, by looking at the central part of the Black Sea we may notice that these resources do not exceed 7 m/s.

Previous researche highlighted the fact that during the winter time (December-January-February), the wind conditions from the Black Sea present a peak in terms of energy level [71]. Figure 4 is focused on these conditions (average values), where compared to the full-time distribution the maximum values can go up to 9.44 m/s (+11.86%). For this season, the higher wind conditions from the Azov Sea are similar to the ones from the Black Sea, being expected some changes in terms of the spatial distribution. For example, the influence of the Azov Sea conditions is also visible in the Black Sea area, near the Kerci area being expected a hot spot that fill the space between land and the 50 km isoline. This can be beneficial for the development of a wind project, but on the other hand can provide some limitations for the maritime navigation operating in this sector. In the western part, there is an elongated area of high wind resources that mainly cover the offshore area of Romania (>50 km), the presence of these resources being also visible in the north (Ukraine) and south (Bulgaria). Much lower resources of 1.18 m/s are expected near the coastal regions from the south-east, this being the case of the coastline defined by the sites Sochi-Batumi-Samsun. On the south-western part of Istanbul, we find the Sea of Marmara, where during the winter season it is possible to expect average conditions that are close to 7 m/s.

A first perspective of the annual energy production (or AEP) is provided in Figure 5, by considering all the wind turbines from Table 1. The performance of each turbine is related to the specific hub height of each generator, namely: turbine T3—100 m; T5—90 m; T10—119 m; T15—150 m. The spatial distribution follows the pattern of the wind resources, the performance of each turbine being closely related to the power curve and rated power of each system. From this region, the Azov Sea represents the best option for the development of a wind project being closely followed by the north-western part of the Black Sea. For example, a single unit of turbine T3 (3 MW) can produce up to 11.04 GWh in the Azov Sea and close to 10 GWh, while as we go to the south-eastern sector the values gradually decrease to 5 GWh.

As expected, the output of turbine T5 (5 MW) is much higher, the AEP output being 2× higher than in the case of turbine T3. A similar pattern is noticed when we go from turbine T5 to T10, or from turbine T10 to T15, respectively. For the turbine T5 (Figure 5b), the spatial pattern remains relatively similar as in the case of T3, with the mention that turbine T5 seems to perform much better in the offshore areas from the north-western part where constant values of 22 GWh are obtained. For the turbines T10 (10 MW) and T15 (15 MW) the values go up to 46.38 and 89 GWh, respectively. In the case of turbine T15, a hot spot of energy comparable to the one from the Azov Sea, occurs near the Odessa area.

The performance of turbine T3 is highlighted in Figure 6, considering only some representative months of the year, that can be associated with the spring, summer, autumn and winter season. It is expected that the spatial distribution of the remaining wind turbines (T5, T10 and T15) will be relatively close to these ones, the expected values being easily deduced based on the information provided in Figure 5.

During June we can expect much lower performance, the best results being related to the Azov Sea and the western coastal area of the Black Sea (Odessa-Sulina), where a maximum of 0.68 GWh is generated. The production gradually increases as we go to September, with a maximum of 0.92 GWh accounted for the northern part of the Azov Sea and some hot spots in the south-western area of the Black Sea that cover the Sea of Marmara and the regions from Istanbul (nearshore) or Zonguldak (offshore), respectively. The values expected for March and December are on the same level, being noticed some spatial variations of the wind fields from the center and north-western part of the Black Sea.

Besides the spatial evaluation of the wind resources and the performance of some state-of-the-art wind turbines, another objective of the present work is to identify the expected hydrogen production related to the electrolyser systems mentioned in Table 1. A first analysis is provided in Figure 7, where the equivalent number of PEM1 units were identified based on the AEP values generated by a single unit of wind turbine (T3, T5, T10 and T15). According to these results, the expected values do not exceed one unit, which means that more wind turbines will be required in order to cover the full performance of a single PEM. For example, if we express these values in percentages the output of turbine T3 will be enough to cover a maximum of 6.7%, values that gradually increase to 14% for T5, 28% for T10 and 54% in the case of T15, respectively. In terms of spatial distribution, there are some regional hot-spots located near the Azov Sea and the north-western part of the Black Sea, with the mention that for the Black Sea these fields tend to expand to the southern area as we go from turbine T3 to turbine T15.

A comprehensive overview of this indicator is presented in

Table 3. Equivalent numbers of PEMs powered by a single unit of wind turbine (T3, T5, T10 and T15).

	Turbine 3 MW	Turbine 5 MW	Turbine 10 MW	Turbine 15 MW
PEM1	0.067	0.14	0.28	0.54
PEM2	0.26	0.55	1.11	2.13
PEM3	0.44	0.93	1.87	3.59
PEM4	0.98	2.07	4.16	7.95

, which also incorporates the remaining PEMs. A different pattern is noticed in the case of the PEM2, PEM3 and PEM4, where a single wind turbine can power multiple arrays of electrolysers. For example, in the case of PEM2 these values go from 0.26 to 2.13 units, values that increase to 0.44 to 3.59 units in the case of PEM3. For the PEM4, a single turbine of 3 MW is enough to power one unit of this type. Significant growth is expected as we consider turbines defined by higher capacity, this being the case of T5 (2.07 units), T10 (4.16 units) or T15 (7.95 units), respectively.

The hydrogen production of all four PEMs is indicated in Figure 8, where only the electricity output of turbine T3 was taken into account. According to this, the hydrogen production is much higher in the case of the PEM1 and PEM2, reaching maximum values of 195.6 and 191.8 tons/year, respectively. The spatial distribution of the PEM3 and PEM 4 is relatively similar, while the maximum values oscillates between 160.9 and 161.7 tons/year. As can be noticed from Table 3, this production can be obtained by using a single unit of PEM, the difference being related to the capacity use of each system (ex: 6.7%, 98%). For the sites located in the south-eastern sector, hydrogen production can be expected to go up to 50 tons/year in the offshore areas.

As we go to a wind turbine of a much higher capacity (Figure 9), we can notice an increase in the hydrogen production. These values can be obtained by using a single unit of electrolyser, except for PEM4 where two units will be required. In terms of hydrogen production, the PEM1 and PEM2 systems exceed 400 tons/year in the Azov Sea and north-western part of the Black Sea, presenting a spatial distribution that is relatively similar. The performance of the PEM3 and PEM4 is relatively in the same range, with maximum hydrogen outputs of 338 tons/year. The coastal area defined by Sochi-Batumi-Samsun sites (south-east) is defined by much lower performance, reaching minimum hydrogen productions of 0.3 tons/year.

Figure 10 highlights the hydrogen production related to the turbine T10 (10 MW), where only one unit of PEM1 will be required compared to the other PEMs, where the number of systems start to increase. Best performance are noticed in the same spots as in the case of turbine T3 and T5, being expected from the PEM1 with a maximum output of 824.20 tons/year, being followed by PEM2 with 800 tons/year. In the case of PEM3 a maximum of 681 tons/year can be reached if two devices are being considered, while in the case of PEM4 an output of 678 tons/year is expected from five electrolysers. With 0.08 tons/year, the south-eastern sector presents a much lower performance than in the case of T3 and T5.

Figure 11 is related to the turbine T15 (15 MW), where we can notice that compared to the previous turbines the hot-spots area that occur in the western part of the Black Sea is gradually expanding to the central part of this basin. The PEM1 and PEM 2 can be grouped in terms of hydrogen production with a maximum of 1575 and 1545 tons/years, but with the mention that the PEM1 will run only on a 54% capacity compared to PEM2 where 2.13 electrolysers will need to be installed. For the PEM3 and PEM4, the hydrogen production is rated at a maximum of 1300 tons/year, with the mention that the number of PEM4 electrolysers will be almost double than in the case of PEM3.

The performance of the PEM systems were evaluated by considering a 90% value. Nevertheless, the specific electrolysis efficiency of a particular system can be estimated as follows [72]:

$${\eta }_{el}={\displaystyle \frac{E_{H_2}}{{ec}_{el}}}·100$$

(4)

where $E_{H_2}$ is the energy contained in the produced hydrogen in $\mathrm{k}\mathrm{W}\mathrm{h}/\mathrm{k}\mathrm{g}{\mathrm{H}}_2$, ${ec}_{el}$ is the electrolysis energy consumption. According to this equation, we may expect a PEMs efficiency close to: PEM1 = 65.4%; PEM2 = 64.1%; PEM3 = 54.0%; PEM4 = 53.8%.

Table 4. The expected hydrogen production (in tons/year) by considering the base scenario (η_el = 90%) and the adjusted efficiency of each PEM. The values are indicated in terms of the lowest-highest values of each spatial map (Figure 8, Figure 9, Figure 10 and Figure 11).

PEM →	PEM1	PEM2	PEM3	PEM4
Turbine ↓
$\left(\mathrm{a}\right) {\eta }_{el}$	90%
T3	0.23–196	0.23–192	0.20–162	0.20–161
T5	0.37–410	0.37–402	0.31–339	0.31–337
T10	0.1–824	0.1–808	0.08–681	0.08–678
T15	2.18–1575	2.14–1545	1.81–1302	1.80–1296
$\left(\mathrm{b}\right) {\eta }_{el}$	65.4%	64.1%	54%	53.8%
T3	0.17–142	0.16–137	0.11–97	0.11–96
T5	0.27–298	0.26–286	0.18–203	0.18–202
T10	0.07–599	0.07–576	0.04–409	0.04–405
T15	1.6–1145	1.5–1100	1.08–781	1.07–774

presents the expected hydrogen production of the PEMs, by considering the base scenario (90%) and the adjusted efficiency. Figure 8, Figure 9, Figure 10 and Figure 11 illustrate the minimum and maximum values for all evaluated PEMs, while the table displays the corresponding hydrogen generation for each PEM. A notable variation is observed in the values computed with Equation (4), particularly for PEM3 and PEM4. For the PEM1, the maximum hydrogen output varies between 142 and 1145 tons/year, according to the selected wind turbine, these values gradually decrease to: 137–1100 tons/year (PEM2); 97–781 tons/year (PEM3); 96–774 tons/year (PEM4).

4. Conclusions

The marine areas are suitable for the implementation of power-to-X philosophy, where the surplus of renewable energy can be converted into other forms of power such as fuel, gas or heat, respectively. The offshore wind sector is currently regarded as a mature industry, as evidenced by the recommissioning of old wind turbines throughout the repowering process. The marine wind power and the hydrogen production can go hand in hand, since they meet some basic requirements, such as: (a) access to important natural water resource; (b) connection to a power system; (c) use of remote location that limits the occurrence of hazardous events; (d) possibility to add additional energy sources (ex: solar or wave) to boost the hydrogen production. From the European area, most of the offshore wind projects are developed in the northern part, but gradually some projects are starting to be implemented in new areas, such as the Mediterranean Sea (Beleolico project, Italy). The Black Sea area, represents another hot-spot area in terms of wind energy, especially in the case of Romania’s Exclusive Economic Zone where wind projects located in the range of 3 to 7 GW are expected to be developed [73].

In this context, the aim of the present work was to develop several scenarios where some state-of-the-art offshore wind turbines were coupled to several electrolysers (or PEMs) that are available on the market. From this perspective, the novelty of the work lies in the fact that it sought to establish a potential link between the Black Sea wind potential and hydrogen production for the first time. The results are being provided in terms of spatial maps, where a contour line marks a 50 km distance from the shore was highlighted. This can be considered a realistic boundary for the development of a marine project, although at this moment there are indicators that a 70 km threshold can be reached [74]. In addition, the wind conditions of some nearby seas are also visible, as in the case of Sea of Azov (north) or Sea of Marmara (south-east), respectively.

Several wind turbines rated between 3 and 15 MW were considered, their electricity output being estimated at their hub height and only for a single unit. By using it as an input, the ERA5 data (hourly values) covering the 10-year interval 2015–2024, was possible to identify their performance for the entire Black Sea basin. At this point, we need to highlight that the performance of different wind turbines were already performed for the Black Sea area by various researchers. Nevertheless, in this case, the performance of the turbines were made on a basin level, by also including some large systems (ex: 10 and 15 MW), which can be considered as an element of novelty.

From the considered PEMs, it was noticed that the PEM1 is the most performant one, and regardless of the wind turbine considered, this module will not reach its full capacity (ex: 54% for turbine T15). As we go from PEM2 to PEM4, the number of PEM modules increase reaching a maximum of 8 modules in the case of PEM4 (and turbine T15). The hydrogen production closely follows the spatial distribution of the wind resources, more promising results being expected in the north-western part of the Black Sea and near the Sea of Azov, respectively. Nevertheless, taking into account the volatile geo-political situation from the vicinity of Crimean Peninsula, it is hard to believe that a renewable project will represent a priority at this moment. As expected, the hydrogen output increases from turbine T3 to turbine T15, being noticed values in the range of 196 and 1575 tons/year. In this estimation, a 90% efficiency of PEMs was used as a reference.

This study’s hydrogen production model operates under the premise of static functionality, lacking mechanisms for storage or dynamic production adjustments. This methodology simplifies the analysis; however, it may result in an overestimation of system efficiency under actual conditions, where variations in renewable energy and fluctuating hydrogen demand require flexible mechanisms. In the future, expanding the model to incorporate hydrogen storage or adaptive operational strategies could yield more precise assessments of the system’s economic viability and sustainability.

The Black Sea region is a promising location for marine renewable energy projects. As of right now, offshore wind resources are the most promising expectation; they are anticipated to develop soon in certain pilot zone areas associated with the coastal environment of Romania. An offshore wind project that is linked to the Crimean Peninsula’s coastal regions can be put into function shortly and can have an impact on the production of hydrogen or electricity. Regarding wave power, the Black Sea, being an enclosed basin, exhibits considerably lower energy levels compared to oceanic shorelines. Prior studies indicated that a wave farm in this region could serve more effectively as a coastal defence mechanism than as an energy source. The lakes near the Black Sea were identified as a potential site for the establishment of floating solar projects. Perhaps the Black Sea basin should receive more attention in this case rather than ecological concerns like bird migrations, which some researchers may find to be sensitive subjects.

Finally, we need to mention that the present work is ongoing and since the hydrogen production seems to be a hot-topic we will try to identify some new applications for the Black Sea environment. This may include economic analysis, identifying the joint performance of a marine wind farm and PEMs modules and establishing the implications of the power-to-x concept in the decarbonization of the regional ports.