Potential of Renewable Energy in Jamaica’s Power Sector: Feasibility Analysis of Biogas Production for Electricity Generation
Round 1
Reviewer 1 Report
The comments on this paper are attached.
Comments for author File: 
Comments.pdf
Author Response
Thank you very much for taking the time to revise our manuscript. Please find the response to your comments/suggestions in the attached file.
Author Response File: Author Response.pdf
Reviewer 2 Report
This paper gives an interesting insight in the Jamaican energy system transition and the potential for biogas production from agricultural residues. The topic as such is highly relevant, however I have a few concerns regarding the execution and presentation. I will list some of the major things here and provide a more comprehensive list of comments in the attached manuscript.
First of all, the main conclusion that biogas could cover up to 13% of the domestic electricity demand is not convincingly supported by the results. There seems to be some confusion regarding energy and power, which goes back to calculations in the results section (Table 5). Perhaps this is just a case of using the wrong units, but it needs to be sorted out.
The structure could be improved. Part of the problem description doesn't show up until 1.4 (high dependence on solid fuels --> negative effects on public health). The introduction should give a full problem description, leading up to the objective of the study. Moreover, there are several parts of the manuscript which seem to be in the wrong section.
Energy production potential is probably not the best angle to motivate anaerobic digestion of animal manure, as it has a relatively low ratio of total solids and low methane yield compared to e.g. food waste. The potential for solar electricity should be much higher and cheaper to realize. A better reason for fermenting manure is to reduce methane emissions, while also getting renewable energy and enhanced biofertilizer as a bonus.
The calculations behind Table 5 are not very easy to comprehend (partly because of the units, as mentioned earlier). How come the potential in CASE 5 (bagasse + pig manure) is only half as high as single-digestion of pig manure?
The list of references include a link to a local file on someone’s computer, as well as an unpublished master’s thesis.
Comments for author File: Comments.pdf
Author Response
Thank you very much for taking the time to revise our manuscript. Please find the response to your comments/suggestions in the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
The article deals with a very current issue - the use of renewable energy sources. The authors have demonstrated good research skills. However, in order to raise the merit of the study, the reviewer recommends: (1) definition of the main purpose and research hypothesis in the abstract as well as in the introduction; (2) presentation in the 'results and discussion' section the limitations of the research carried out (in addition, it is suggested that the word findings be used instead of reults); (3) the literature review should include articles that have appeared in 'Energies' (the literature review is the weakest part of the study); (4) to describe in the 'discussion and findings' section future research directions based on the limitations presented; (5) shorten the introduction, it is too long compared to the rest of the article.
Author Response
Thank you very much for taking the time to revise our manuscript. Please find the response to your comments/suggestions in the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
This paper in its current form is acceptable.
Author Response
Thank you very much for taking the time to revise our paper. Please find the response to your comments/suggestions in the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors have made some improvements and corrections following the previous comments from reviewers. However, the central calculations contain a number of major errors, due to lack of diligence and criticality when it comes to input data, computation and units. This makes it very hard to evaluate the discussion and conclusions, as they build upon inaccurate results and nonsensical comparisons of numbers with different units.
Comments for author File: Comments.pdf
Author Response
Thank you very much for taking the time to revise our manuscript. Please find the response to your comments/suggestions in the attachment.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Delete 'Correspondence' - repeated twice.
Pg2, suddenly the paragraph format is double spaced?
Redraw Fig 3, all the fonts overlap with each other.
For all Figures, I would recommend to make sure the font size in the Figure is not too big as compared to the Font size of the Figure's caption.
Equations 1-7, do you have the references to where you get this? Also, the format of Equations does not follow MDPI template.
Table 6, only 1 ref? What about Cattle and chicken?
Remove List of Figures and Tables from the last page.
It would be nice if you can produce a costing analysis for a biogas plant - to see the value, IRR, payback for a simple case study perhaps?
Reviewer 2 Report
Although the topic of the paper is quite interesting, there are many inaccuracies due mainly to lack of attention during writing. The authors should better read the instructions for authors. In the current format the paper must be rejected, but with due attention during the revision, it can be reconsidered.
A list of more specific suggestions follows.
Introduction
A reference should be added on the National Development Plan, and the sentence "Thus, shifting resources...." should be joined to the previous one using semicolon instead of a point.
The text should be better formatted according to the template of the journal. See, for instance the three lines preceding Figure 1 and other points in the text.
Just after Figure 1, the authors mention "Figure 3". Numbering is wrong, because Figure 3 can only be mentioned after Figure 2.
It would be preferable to cite the authors before citations [5,6] in the text. Similarly, in other citations along the text.
Subsection 1.2. Why 1.2? Where the 1.1. subsection is?
Title of Subsection 1.4 must be written in italic, not in bold.
Subsection 1.5. Please add references to the National Energy Policy 2009-2030 (NEP) and Biofuels Policy (2010-2030)
Subsection 1.6. Please close the quotation marks at the end of the definition of anaerobic digestion
Figure 3. "Crop %" in the legend of the abscissae axis overlaps with the word "Condiments".
Methodology
Do not use a comma after the number of equations.
The authors should mention in some point of the text the importance of choosing co-products to be co-digested so as to reach a suitable C/N ratio for anaerobic digestion.
Please, add a reference at the end of the sentence before Eq. (4). "successful research".
Use low case "kg" to indicate "kilogram" in Table 2 instead of "Kg".
Results and Discussion
Section 3.1. 2nd line. (Figure 5) should be between brackets. The same 5 lines after Figure 5 legend.
Section 3.2. Add a reference after citation of the Food and Agriculture Organization of the United Nations (FAO)
Figure 6. Add the units of the numbers on the abscissae axis: 5,000,000 etc.
References to the works of Grant & Marshalleck, 2008; and Salam, 2009 must be numbered in the text, between [...].
Numbering of the figure in the penultimate line of section 3.2 (Figure 4) is likely to be wrong. Please, check numbering of all Figures and Tables throughout the text. There is a great confusion.
Meaning of the unusual unit "MWhel" should be specified the firt time it is used on the text.
Section 3.3. Table 5 should be put close to its first mentioning on the manuscript. Also, all units in Table 5 should be between brackets. Please check the right number of decimal digits of figures in this table. For instance: decimal digits are unnecessary in 106,886.78, etc.
Section 3.4. References are needed after the sentence “Developing countries such as Brazil, India, and Mauritius have found ways to stabilize sugar-cane production in the local market while being internationally competitiv”.
Table 6. If ref. [6] applies to all Pig, Cattle and Chicken, there is no need to include a column for this reference. it can be cited in the legend.
Appendix A. The content of this appendix must be written according to the Instructions.
Appendix B. I cannot understand why this table is called Table 10. Where Tables 7 to 9 are? In addition, Appendixes must be cited in the text.
Reviewer 3 Report
Find attached is the comments for authors
Comments for author File: Comments.pdf
Reviewer 4 Report
Please see attached file
Comments for author File: Comments.pdf
Reviewer 5 Report
First of all, I have to mention that although the topic is not in my area of expertise, it was so interesting for me. In fact, not only was it interesting, but it's an essential study for our society with many applicable results. The paper uses information from the available government database to calculate the amount of biogas production. The theoretical assessment uses the number of animals available, the collection factor, the residue generation, and the amount of biogas production per cubic meter per kilogram. The results of the study show that sugarcane bagasse in combination with animal manure enriches the potential for generating biogas through anaerobic fermentation and co-fermentation. Overall, this paper is well written and well structured and I recommend acceptance.
