*3.4. Preliminary Estimation of P2H Plants Size*

Based on the preliminary assessment of the hydrogen blending threshold, an estimation of the P2H size and distribution can be performed: a total installed P2H plant output capacity of 77.5 MW can be considered for the Italian framework in the first green hydrogen development phase. To produce such amount of energy, in accordance to Section 2.3, P2H plants should be designed with (i) an electrolysis section and (ii) a compression section and (iii) other auxiliaries. By using Equations (19)–(22) the total electrical power supply for electrolyzers and compressors is calculated equal to 127.2 MW. Assuming the safety factor equal to 5% to take into account other auxiliaries' consumption a total power supply of 133.6 MW can be assumed. From an energy point of view, this would result in an annual electrical consumption of 467.6 GWh/year. Results are summarized in Table 9.

**Table 9.** Preliminary estimation of Italian P2H plants' total size.


#### *3.5. Preliminary Estimation of P2H Plants Distribution*

The total installed capacity of Italian P2H plants was distributed in the Italian territory based on the following consideration. Particularly, it was assumed that natural gas flowrate at the import points is the minimum when the total Italian gas flowrate is the minimum. Therefore, it is assumed in this preliminary evaluation that the control of the gas flowrate at each import point is proportional to the total gas flowrate in the network. A detailed analysis of natural gas flowrates for each import points will be performed in a following paper.

Then, P2H plants capacity was divided per each location as reported in Table 10 are calculated. In Table 10 the natural gas flowrate from national fields is not shown. In Figure 6 the size and the location of the P2H plants are shown in the Italian territory in comparison with already installed PV and wind turbine power plants capacity.


**Table 10.** Preliminary estimation of Italian P2H plants' total size.

**Figure 6.** Location and size of the P2H plants in Italy and relation with regional renewable power availability.

### *3.6. Preliminary Economic Assessment for Italian P2H Plants*

Based on Equations (23)–(26) and values introduced by Table 11, a CAPEX equal to 487.5 M€ can be estimated. As shown in Table 10, the physical storage volume is responsible for the highest voice of cost. In fact, ATEX certified components, instrumentation and high-pressure stainless steel storage tank are required for safety reason.


**Table 11.** Capital expenditure (CAPEX) parameters.

#### *3.7. Discussion and Next Steps*

Figure 6 defines the optimum location of the first kind of P2H plants for low percentage green hydrogen blending in Italy. The final results have been achieved by considering only (i) the definition of hydrogen blending threshold to be not overcome, and (ii) the hydrogen injection close to the principal connections of the natural gas network. It is interesting to note how the final result is coherent with energy consumption. In fact, 71% of hydrogen produced by the P2H plants would be blended in the north area of the natural gas network, wherein energy demand is the highest. Therefore, hydrogen generation and blending are optimized in relation with energy demand. Nevertheless, a relevant component of the P2H plants location strategy should consider not only consumers' location, but also renewable power availability and/or potential. Figure 6 shows that, due to the conservative hypothesis related to the maximum hydrogen blending threshold identified in the paper, the installed power required for each P2H plant related with a principal connection of the natural gas network is much lower than the installed renewable power (PV plus wind) already available in the Regions potentially involved.

Further steps are needed to identify in detail if and which existing renewable power plants can be directly connected to the new P2H plants in each region. An economic evaluation will be performed starting from the available GIS database about natural gas network and renewable power plants. Nevertheless, Apulia region will be taken into consideration as a relevant case study too: in fact, while Apulia currently has no relevant natural gas network connection, it has the highest power production from renewables. Therefore, Apulia is the most interesting Italian region to be studied as a reference for the second step of the national hydrogen strategy, i.e., hydrogen blending over the threshold as defined in the paper.

#### **4. Conclusions**

The paper aims to assess the actual green hydrogen potential in Italy based on natural gas network characteristics. The estimation has been performed by considering some relevant hypothesis and limitations to minimize the impact on natural gas infrastructure and end-users, thus allowing a short-term implementation at local level of P2H installations for green hydrogen blending. The paper shows how up to 8100 ton/year of green hydrogen blending, i.e., 715,000 Sm3/year could be injected right now in the existing natural gas network with a proper location and sizing of P2H plants. This green hydrogen potential corresponds to an installed capacity of about 78 MW of electrolyzers and

about 488 M€ of investment. Further analysis is needed to better evaluate the geographical positioning of P2H plants, including also integration with existing renewable power plants.

The objective of the EU hydrogen strategy is to install in the first phase of its development, from 2020 up to 2024, at least 6 GW of renewable hydrogen electrolyzers and the production of up to 1 million ton of renewable hydrogen. Therefore, Italy could give at least a 1% contribution to this strategy by immediately implementing the realization of P2H plants for green hydrogen blending as described in the paper. Nevertheless, the results of the preliminary assessment show how the design and development of more complex strategies, including natural gas network revamping and end-users adaptation, are necessary if the ambitious goals of the European strategy want to be reached by Italy and also by the Member States. That is why the Italian government is urgently called to agree on a national hydrogen strategy to boost energy transition and stimulate the technological innovation of the Italian hydrogen industry.

**Author Contributions:** M.P. conducted the conceptualization and was in charge for the revision of the document; A.G. prepared the methodology and elaborated data; C.S. provided comments and supported designing the study. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Italian Minister of University and Research (MUR) in the framework of the "*SuperP2G: Synergies Utilizing Renewable Power Regionally by Means of Power To Gas*" project under the joint programming initiative "*ERA-Net Smart Energy Systems—Focus initiative integrated, Regional Energy Systems*".

**Conflicts of Interest:** The authors declare no conflict of interest.
