ASEAN’s Energy Transition towards Cleaner Energy System: Energy Modelling Scenarios and Policy Implications
Round 1
Reviewer 1 Report
The authors have produced an interesting analysis of potential energy mixes among ASEAN countries. With some major revisions, the manuscript can make a good contribution to the literature. As it is currently, though, the manuscript is long, difficult to parse, and requires more explanation of methods and policy implications. I hope the following comments are helpful.
1. The introduction feels too long. I'd advise the authors relocate lines 1-97 to their own dedicated "Background: Energy Transition Issues in ASEAN countries" section, at the very beginning of the literature review. The paper only really starts introducing the research questions, etc. after line 97.
2. I'd recommend the authors reinforce the framing of the research question, and refer back to that question throughout. Right now, it's not even explicitly stated. I think the question is, "1) What are the projected impacts on greenhouse gas emissions of different potential energy mixes for ASEAN countries, and 2) which energy mix should the region pursue?" Then, the authors should re-reference this in the literature review, the methods, etc.
3. For example, in line 237, the study just jumps right in, but it would be helpful for the reader to repeat the research question, state the method used to answer the question, and explain why it is being used.
4. This study uses a lot of acronyms (APS, POP, AMS, BAU), etc. It's difficult to parse. I would write out most of them and use acronyms only for a few key terms.
5. Why is the paper using underscores ("_"). It's not very standard and looks informal. Also, see previous bit about too many acronyms.
6. Line 266: Early in the Methods, the authors should explicitly define which variables and measures they are using to represent what concepts, including sources. A table of these might be nice. As it is now, it's very hard to follow, I'm afraid.
7. It is not clear to me at all what the LEAP software is doing here. What models is it doing, what input data is it using, etc, what studies have used it before and why should we consider it valid - all these need to be stated.
8. Line 275 or so: Needs clear explanation, like: "This study generates and compares 4 possible energy mixes and their effects on greenhouse gas emissions over time. We break these pathways into four types, each with their own assumptions, including the APS, APS_RE, APS_etc.... The APS refers to [blank], and assumes that states will..."
9. This paper has under 20 references, most of which are the authors' own work. A typical publication has 50+ references to scholarly literature, in my experience. I am concerned that the study does not closely engage with current scholarship in energy policy. For example, there is little discussion of which of these potential social, economic, or political implications of the different energy pathways compared in this study. Below are two formative works in the study of a just transition and socially equitable energy policy.
Heffron, McCauley, and Sovacool (2015)
https://www.sciencedirect.com/science/article/abs/pii/S030142151530077X
McCauley and Heffron's Just Transitions paper
https://research-repository.st-andrews.ac.uk/handle/10023/17583
10. This paper advocates for clean coal technology. The authors need to directly confront in the discussion the obvious problem: if states invest in new infrastructure for cleaner-burning fossil fuels, will they ever actually transition away from fossil fuels?
11. This paper ends with a bullet point summary of ~10 policy recommendations - which should probably be converted into main text. However, they're about all sorts of different things. Please focus the discussion and conclusion into just 2-3 of these findings, ideally by answering directly the central research question, written out explicitly in that section. And, clearly articulate how these findings contribute to the literature outside of your own work.
Author Response
Responses to Reviewer#1:
Dear Editor/Reviewer,
Thank you so much for taking time to comment on this paper. I am very pleased to respond to your comments and you will find my answers placed below each comment and how I have addressed your concerns. Again, thank you so much for taking time in commenting this paper. Please find my responses in the attached file.
Sincerely yours,
Han Phoumin
Fukunari Kimura
Jun Arima
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript discuss the energy modelling scenarios to seek plausible policy options for Association of Southeast Asian Nations (ASEAN) in order to achieve more emissions reductions as well as energy savings, and to assess the extent to which the composition of the energy mix will be changed under various energy policy scenarios.
Comments to the Author
The authors should clearly state the contributions of their work in view of existing state of the art literature.
The authors mentioned “phase 2" while the phase 1 is not clear or defined in line 149?
All evidence need reference such as “China, the United States (US), Europe, and India are the largest emitters, contributing 30%, 15%, 9%, and 84 6% of global GHG emissions, respectively”
What is mean (CCUS) in the line 143?
For these reasons, I think the paper has a great potential, but needs revisions before being acceptable for publication.
Author Response
Responses to Reviewer#2:
Dear Editor/Reviewer,
Thank you so much for taking time to comment on this paper. I am very pleased to respond to your comments and you will find my answers placed below each comment and how I have addressed your concerns. Again, thank you so much for taking time in commenting this paper. Please find my responses in the attached file.
Sincerely yours,
Han Phoumin
Fukunari Kimura
Jun Arima
Author Response File: Author Response.docx
Reviewer 3 Report
Suggestions:
- Section 2: Points to recent updates but there have been additional changes and preparations UNEP & UNEA5 - Policies changes and development. Would be good to tie in recent updates.
- Section 4, page 16: Have you found any pertaining information regarding the innovative nuclear advancements and implementation of SMR - Small Modular Reactors for ASEAN? Their ability to produce safe, clean energy for many decades, in addition, or conjunction, with other clean energy sources. The drawback is cost/funding.
- Section 2: What role plays the use of guidance offered by the ISO standards (ISO 50001 Energy Management, ISO 14065 Greenhouse gas validation, and verification or ISO 14001 – Environmental management and others) in the process of implementing changes within the ASEAN energy system transition? (in conjunction with Paris Agreement). Are they (if) applicable?
Comments / questions:
- Page 2, line 47, the sentence is unclear: Oil will be the largest energy source in the primary energy mix in 2050, at 39.6%, down from 36.9% in 2017.
- Line 99-114 seems like a citation, no source indicated
- There is the different font size used throughout the document – not sure if this is something that must be pointed out; it indicates copy-paste
- Lines 402-408: What is the source of the projected financial investment? If calculated by authors, what were the calculations based on?
- Introduction: Line 51-62, what is the source of the %?
Author Response
Responses to Reviewer#3:
Dear Editor/Reviewer,
Thank you so much for taking time to comment on this paper. I am very pleased to respond to your comments and you will find my answers placed below each comment and how I have addressed your concerns. Again, thank you so much for taking time in commenting this paper. Please find my responses in the attached file.
Sincerely yours,
Han Phoumin
Fukunari Kimura
Jun Arima
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
The authors have thoroughly revised the study, much improving the introduction and methods. It reads a lot more clearly now.
I personally disagree strongly with the authors that clean coal technologies, namely carbon capture and sequestration, is a useful tool going forward. After all, it has barely been tested at scale, and many energy scholars view it as a pipe dream and a deflection from the need to transition to renewables. This study's undertone, that clean coal is a necessary part of Asia's energy transition, is problematic in the same way that saying the nuclear fuel cycle is key to Japan's energy transition.
Neither are well tested or have ever really been used at scale, and both pose problems in gaining local consent from residents. (The bit about the nuclear fuel cycle is just a comparison.)
As a result, I recommend accept for this because the authors have completed the main revisions for the paper, but I personally disagree with the approach used here. I wish the authors well in their future research.
Reviewer 2 Report
The author address all my comments satisfactorily.
