Hybrid Energy Network Management: Simulation and Optimisation of Large Scale PV Coupled with Hydrogen Generation

Round 1

Reviewer 1 Report

Congratulations on the work presented.

1 - Regarding the mathematical model:
a) I think that the mathematical model is well structured, although my suggestion is to consider more than an objective function in the future. This theme is very complex and deserved a multi-objective approach. It is not just the economic issue at stake.
b) I would like to see environmental issues in the objectives, for example, as well as minimizing the use of storage (battery - Figure 1). These issues matter more than economic ones.
c) The lack of water in some places may be a constraint to be taken into account in this type of study.
2- Regarding the results:
a) Regarding the case studies and presentation of results, comparisons are lacking.
b) There is no justification for choosing the case studies used.
c) The graphical presentation of the results is good, but some tables are missing to allow access to more information.

Author Response

First we would like to thank Reviewers for their prompt and accurate reading of the manuscript, in the following (in italics) our answer to reviewers

1 - Regarding the mathematical model:
a) I think that the mathematical model is well structured, although my suggestion is to consider more than an objective function in the future. This theme is very complex and deserved a multi-objective approach. It is not just the economic issue at stake.
It is true and some sentences have been added to the Introduction section to highlight this important issue

b) I would like to see environmental issues in the objectives, for example, as well as minimizing the use of storage (battery - Figure 1). These issues matter more than economic ones.
This issue has been added by a new statement in the introduction and by stating its importance in possible developments of the procedure

c) The lack of water in some places may be a constraint to be taken into account in this type of study.
Also this constraint has been added to the possible developments

2- Regarding the results:
a) Regarding the case studies and presentation of results, comparisons are lacking.
New sentences explaining the results obtained in the case studies have been added. A more detailed comment on results has been added together with a new table summarising some of the data.

b) There is no justification for choosing the case studies used.
Some sentences have been added in the introductory part of the case study to explain why the test case was chosen.

c) The graphical presentation of the results is good, but some tables are missing to allow access to more information.
A trade-off table with values of data shown in figure 7 has been added

Reviewer 2 Report

In the manuscript titled “Hybrid Energy Network Management: simulation and optimisation of large scale PV coupled with Hydrogen Generation”, the authors used a mathematical optimization procedure  to minimize the running cost of a system made up by PV plant with hydrogen production, storage and conversion to electricity, and this work provides the optimization tool within loops of parametric analysis to find out variations of the HES performance with respect to operation data and parameters. I recommend the publication of this paper to Electronics after minor revision. Detailed comments and questions are as following,

1. Line 66 on Page 2, is there some words missing in the statement of “under the for of hydrogen”?
2. Equation (9) on Page 6, is P_fc supposed to be multiplied by η_fc, instead divided by η_fc, compared to Equation (6)?
3. Equation (13) on Page 7, similar question as mentioned in Comment 2, is P_bd supposed to be multiplied by η_bd,instead divided by η_bd?
4. Line 249 on Page 11, the symbol “÷” should be replaced by “-”.
5. What are the key points and information derived from Figure 5 and 6? No discussion or highlights is provided in the main text of manuscript.
6. In the line below Line 262 on Page 12, “The elctrolyser, tank and grid data are the same as used in Case 1”, first, there is a typo for electrolyser. Second, as I understand, there is no tank considered in Case 1, why the statement of “tank and grid data are the same as used in Case 1” is given?
7. Equation (44) on Page 12, I think it is c_fc, not c_el.
8. In Figure 9 on Page 13, the “Sold”, represented by blue box, is given in legend, but no appearance in the figure, does that mean there is no “Sold” data? If so, why the “Sold” is included in legend?
9. In Figure 10 on Page 14, same issue as mentioned in Comment 8, no “Load” or “Purchase” data in the figure, but included in legend.

Author Response

First we would like to thank Reviewers for their prompt and accurate reading of the manuscript, in the following (in italics) our answer to reviewers.

Line 66 on Page 2, is there some words missing in the statement of “under the for of hydrogen”?
we acknowledge the mistake, the statement has been rephrased and the error removed

Equation (9) on Page 6, is Pfc supposed to be multiplied by ηfc, instead divided by ηfc, compared to Equation (6)?
The optimiser uses the electrical variables as decision ones. In this way, in the electrolyser the produced hydrogen mass flow (output variable) is given by the electrical power in input (P_el) multiplied by the efficiency. On the contrary, in the fuel cell the hydrogen mass flow required in output (q_fc) is given by the output electrical power (P_fc) divided by the efficiency.

Equation (13) on Page 7, similar question as mentioned in Comment 2, is Pbd supposed to be multiplied by ηbd,instead divided by ηbd?
Again, as in the previous case, the misunderstanding is created by the different roles of input/output quantities.

Line 249 on Page 11, the symbol “÷” should be replaced by “-”.
The symbol has been replaced

What are the key points and information derived from Figure 5 and 6? No discussion or highlights is provided in the main text of manuscript.
A statement describing the test case and commenting the figures data has been added to the main text.

In the line below Line 262 on Page 12, “The elctrolyser, tank and grid data are the same as used in Case 1”, first, there is a typo for electrolyser. Second, as I understand, there is no tank considered in Case 1, why the statement of “tank and grid data are the same as used in Case 1” is given?
It is true, the tank data now have been added.

Equation (44) on Page 12, I think it is cfc, not cel.
It is true, the mistake has been corrected

In Figure 9 on Page 13, the “Sold”, represented by blue box, is given in legend, but no appearance in the figure, does that mean there is no “Sold” data? If so, why the “Sold” is included in legend?
It is true that the "Sold" contribute is not active in the Case 2, the contribute has been removed from the legend

In Figure 10 on Page 14, same issue as mentioned in Comment 8, no “Load” or “Purchase” data in the figure, but included in legend.
It is true but they have been included as they are options of the optimiser. Their null value has been anyway pointed out in the text.