A Location Model for the Agro-Biomethane Plants in Supporting the REPowerEU Energy Policy Program

Reviewer’s comments

Authors’ answers

Page 1, Line 11. You can replace "Russian natural gas" with "imported natural gas”.

Thanks reviewer for this suggestion. The authors have revised Line 11 replacing “Russian with imported”.

Figure 1 is not clear, the font size of sub-headings is small as well as the wording around the figure is not clear.

Thanks reviewer for this suggestion. The authors have improved the figure quality, increasing the font-size of sub-headings and lightening the box colours.

Page 9, line 341, the equation and the description below of the parameters must be the same. Also authors have to add (1) to this equation.

Thanks reviewer for this suggestion. The authors have added (1) to this equation and checked and correct the parameters’ styling.

Page 10, the equations need to start from (2). 

Thanks reviewer for this suggestion. The first equation and the following have changed numbers.

The conclusion is lacking future recommendation for this research work. Please add a part related to this at the end of the conclusion. Also, please focus on how to generalize the study universally.

Thanks reviewer for this suggestion. The authors have revised in this way:

The model is unique in that as it combines methodologies from different scientific disciplines, each of which is not particularly complex to develop, which is the real added value of this analysis. Given the relative simplicity of the basic methodologies used, there are no particular obstacles to replicate this model in different territorial contexts. Nevertheless, as a great deal of data specific to the area under analysis is required, the limits to its application may stem from the difficulty of finding precise data on electricity production at provincial level, on the exact location of the natural gas network, and on the production of agro-food by-products. Often, as in this case, different sources have to be joined to obtain this data, with all the methodological limitations that this entails. Future developments of the model could consider extending the analysis to the logistical management of the raw material, both from an economic and geographical point of view, as well as the possibility of examining alternative uses of the biomethane produced with respect to feeding it into the grid, and whether these alternatives have an impact on the choice of location.

Reviewer’s comments

Authors’ answers

English should be polished.

Thanks reviewer for this suggestion. The authors have checked again the text with an English proof reader.

All the tables should be revised, try to make them concise in the manuscript.

Thanks reviewer for this suggestion. The authors have deleted the Table 1, 5 and 6, incorporating them in the text.

Do you have the undated data of Electricity production in the target province? And also other statistic data to support your idea? I do not think the data are sufficient at present.

Did you mean updated data? There is no official updated data for the target province. The authors have used the last publication released by TERNA in 2022. This latter is the Italy’s primary transmission and dispatching operator: the most important and reliable reference at national level.

Some minor mistakes should be revised about the language.

As said before, the authors have checked again the text with an English proof reader.

All the equations should be treated with serial number

Thanks, the authors have corrected the equations’ number.

And there are some typing mistakes as well.

Thanks, the authors have corrected them.

Reviewer’s comments

Authors’ answers

1) Line 40: please correct “20250”

Thanks reviewer for this suggestion. The authors have corrected.

2) Line 112: “tasted” should read “tested”;

Thanks reviewer for this suggestion. The authors have corrected.

3) Line 222: “Based the” should read “Based on the”;

Thanks reviewer for this suggestion. The authors have corrected.

4) Line 239: I wonder if the authors need 13 references to support the development of location theory. I would suggest citing seminal works and the latest insights on the subject.

Thanks reviewer for this suggestion. The authors have reduced the references.

5) Line 269 and Table 2: “... and losing weight”: I did not understand this expression.

Thanks reviewer for this suggestion. The authors have explained what they wanted to say, as follows:

“(located in specific places and “losing weight” that is, when the weight of the raw material is only partially found in the finished product unit)

6) Table 3: I would suggest changing the unit “q” (which I suppose denotes quintal) to a more common unit (kg or tonne).

Thanks reviewer for this suggestion. The authors have converted quintals in tonnes.

7) Line 322: What type of geoprocessing operations are the authors referring to? and how were the different attributes accounted for (any kind of weighting?). Please clarify .

Thanks reviewer for this suggestion. The authors have explained better the geoprocessing operations, as follows:

 The main geoprocessing operations were: geolocalization, overlaps and spatial relationships between different information layers, centroid calculation, merge vector layer, buffer analysis, etc.

8)Line 327 and Figure 5: pre-existing biogas/biomethane facilities were also considered in the assessment?

Currently, the agro-biomethane plants are not present in the target province: one is in the phase of realization. The pre-existing biogas plants are, instead, nine and they have not been considered in the analysis. They are mainly of small size ones.

9) Line 344: please add “(in euros per tonne)”

Thanks reviewer for this suggestion. The authors have added in euros per tonne.

10) Line 372: I wonder if 7 references are required to make the point (especially when 6 are for PV systems)

Thanks reviewer for this suggestion. The authors have reduced the references.

11) Line 379: If equation numbering is required, I would suggest also including the equation of line 342

Thanks reviewer for this suggestion. The authors have added for all equation the correct serial number.

12) Line 394: starting year (ys) and ending year (ye) are missing in the legend.

Thanks reviewer for this suggestion. The authors have added starting year (ys) and ending year (ye) in the text, as follows:

“y_s is starting year and y_e is ending year”.

13) Line 400: I wonder how the “Other conditions” of Table 2 were taken into account for the calculation of the biomethane potential of Figure 5. Lines 474-476 do not provide any additional insights in this respect.

Thanks reviewer for this suggestion. The authors have added, in line with the recommendations number 15, this sentence as follows:

“Consequently, the most interesting geographical areas are mainly concentrated in the northern-central part of the province due to the presence of the higher amount of feedstock and the existing methane pipeline system, which represents a technical-economic constraint, together with other environmental conditions, including the presence of economic incentives and landscape constraints (as indicated in Table 2).”.

14) Table 4: please provide the source for industrial data (e.g. maintenance costs)

Thanks reviewer for this suggestion. The authors have added the source in Table 4, now Table 3, as follows:

“Legend: The risk-free interest rate is calculated as the average return of 20 Year BTP in January 2023 [42]. Technical data on biomethane plants were provided by Società Italiana Gasdotti.”

15) Figure 5: According to the approach, the southern part of Foggia province (despite its production potential) rests unutilized just because there is no pipeline nearby; please clarify.

Thanks reviewer for this suggestion. The authors have added, in line with the recommendations number 13, this sentence, as follows:

“Consequently, the most interesting geographical areas are mainly concentrated in the northern-central part of the province due to the presence of the higher amount of feedstock and the existing methane pipeline system, which represents a technical-economic constraint, together with other environmental conditions, including the presence of economic incentives and landscape constraints (as indicated in Table 2). Indeed, this last element is a type of infrastructural and economic constraint on the first delimitation of the geographical areas, which therefore had to fall within this boundary.”

16) Table 6: please include references for the data provided.

Thanks reviewer for this suggestion. The authors have deleted the Table 6 and inserted the content in the text, adding the lacking reference.

Minor editing of English language required. For instance, in line 87 "The first has carried" should read "The first has been carried".

Thanks reviewer for this suggestion. The authors have checked again the text with an English proof reader.

Reviewer’s comments

Authors’ answers

1. Check grammatical and punctuation errors throughout the manuscript.

Thanks reviewer for this suggestion. The authors have checked again the text with an English proof reader.

2. Line 41  "By 20250" incorrect year.

Thanks reviewer for this suggestion. The authors have corrected it.

3. I encourage you to re-analyze the introduction and remove repetitions as well as include examples of selected biomethane facilities.

Thanks reviewer for this suggestion. The authors removed the part that was just reported in the discussion section and included number of the current existing biomethane facilities in Italy, as follows:

“On the base of the best author’s knowledge, only a couple of studies have been published about the agro-biomethane plants’ location model, as discussed in details in the section 3, but they present some limits as not considering the different feedstock typologies for the biomethane production as well as its integration with other RES to design an energy diffuse system”.

“Currently in Italy there are over 2,000 biogas plants and around 85 biomethane production plants, located mainly in the northern regions [11]”.

4. Figure 2 could be clearer.

Thanks reviewer for this suggestion. The authors have made clearer the figure 2.

5. Please present the data collected in table 1 schematically and delete the table.

Thanks reviewer for this suggestion. The authors have deleted the Table 1.

To sum up, the issues discussed in the article are current and important in the context of becoming independent from Russian natural gas. However, when reading the article, you may get the impression that a lot of information is duplicated, so I encourage you to re-analyze the article and shorten it.

The authors have shortened the manuscript mainly reducing the introduction section and deleting 3 out of 6 Tables.

Minor editing of English language required.

Thanks reviewer for this suggestion. The authors have checked again the text with an English proof reader.

Reviewer’s comments

Authors’ answers

Since the analysis is provided for Foggia, the title should be slightly changed in order to provide that this is the case study done for Foggia. 

Thanks reviewer for this suggestion. The authors prefer to leave the title as it is because the research aims mainly to propose a replicable predictive model for a generic rural area. The eventual specification could limit the diffusion in the international indexed database.  

Also, it is not quite clear what is the scientific novelty of this manuscript.

Even if the authors have underlined the scientific novelty of this manuscript in the final part of the Introduction, they have added some words as follows:

“Thus, research’s novelty, besides standing on an interdisciplinary approach to assess the territorial complexity under the geolocalization framework, lays on filling the following gaps: i) proposing a new and more complete location model; ii) applying a territorialisation approach to the EU energy planning and policy; iii) focusing on the agro-biomethane production for its integration in the EU bioenergy policy”.

Why did you use 45 km distance range limit, instead of some other values shown in literature? Provide either reference using this value or some kind of proof for this.

The 45 km limit is a result of the economic analysis carried out. The aim of the economic analysis is to verify the conditions necessary for the biogas plants analysed to achieve a return similar to that of other renewable energy plants, estimated in the literature to be around 20% (IRR=20%).

The economic analysis uses the constraints resulting from the analysis of the territory, i.e. the composition of the diet, imposed as a target IRR=20%, and the result is the definition of the optimal distance between the plant and the raw material production sites. The result, as shown in Table 5, is that the materials needed to feed the plant, in the specific case analysed of the province of Foggia, should not be transported more than 45 km.

For the references in Italian language, provide also translation in English.

Thanks reviewer for this suggestion. The authors have translated.

Reviewer’s comments

Authors’ answers

Explain in more detail how the raw materials and their proportions, quantities, and BMP for the anaerobic digester were selected.

The authors stress that the specific quantities/proportions of feedstock diet derive from both the size of the anaerobic digester, that indicates the total amount per day necessary, the Annex IX of the Renewable Energy Directive (EU) 2018/2001, concerning the list of feedstock suitable for biomethane production present in the case–study area, and the best environmental performer raw material. Finally, the BMP is calculated considering the values reported in technical literature (CIB, 2016).

This was just reported in the manuscript:

 […] Then, the best performance regarding environmental (significant reduction of GHGs’ emissions [≥80%] and mainly use of residual feedstock) [….]

Accordingly, it was considered worthwhile the size of 2 MW, that is, 500 m³/h or 12,000 m³/day of biomethane production. Figure 4 shows the feedstock typologies and share necessary to feed the proposed plant, while Table 2 indicates the corresponding yearly amounts and their biochemical methane potentials (BMP), expressed in m³ per tonnes of total weight [35].

Please perform an English revision of the manuscript, and look for typos.

Thanks reviewer for this suggestion. The authors have checked the text with an English proof reader.