Economic, Environmental, and Sociopolitical Aspects of Waste Incineration: A Scoping Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article explores the economic, environmental, and socio political performance of waste incineration energy (WtE-I) in a systematic review manner, which has strong practical significance. However, the article has the following issues that need improvement:

1. Line 31-37：Only mentions the benefits of WtE-I and does not elaborate on why the focus is on "incineration" rather than other technologies，please add relevant information.
2. Line 95-100:Would using only Scopus database for literature search lead to incomplete retrieval? Have you considered adding a database for retrieval?
3. A description of research on waste incineration is missing from the Introduction, please refer to

https://doi.org/10.1080/09593330.2022.2152222；https://doi.org/10.1016/j.biombioe.2024.107245

4. Line 195-197:Is there any relevant data supporting this phenomenon? Please provide additional information.
5. Line 347-352:Is there any relevant solution strategy for the conflict of interest between Brazilian scavengers and the WtE industry? Please provide additional explanation
6. Lines 228-230:Indicate that the model did not compare renewable energy scenarios, and it is suggested to clearly explain how this deficiency affects the applicability of the conclusion in Australia.
7. Lines 374-380:The author only mentioned that the lack of samples in Australia may be due to the industry being in its infancy. It is suggested to add a discussion on whether this gap will weaken the feasibility of policy recommendations?

Author Response

This article explores the economic, environmental, and socio political performance of waste incineration energy (WtE-I) in a systematic review manner, which has strong practical significance. However, the article has the following issues that need improvement:

1. Line 31-37：Only mentions the benefits of WtE-I and does not elaborate on why the focus is on "incineration" rather than other technologies，please add relevant information.

Additional sentence added: The study focused on WtE-I for two reasons; firstly because pyrolysis and gasification are only emerging technologies in the Australian context and secondly to limit the scope of the study to resource capacity.

Additonal sentence at (old) lines 381-84 “Future word may explore this.,” and “widely” added to (old) line 382.

1. Line 95-100:Would using only Scopus database for literature search lead to incomplete retrieval? Have you considered adding a database for retrieval?

We explain the reason for using Scopus in the article: “Scopus was chosen for its advanced search functionality and depth of peer-reviewed literature.” Therefore, we did not consider using another database.

1. A description of research on waste incineration is missing from the Introduction, please refer to

https://doi.org/10.1080/09593330.2022.2152222；

https://doi.org/10.1016/j.biombioe.2024.107245

We do not consider a description of the overall research on waste incineration would be useful in this article. That would have required an additional complementary review process.

1. Line 195-197:Is there any relevant data supporting this phenomenon? Please provide additional information.

Reference 53: sentence added: In 2013, 18 per cent of municipalities employed 387,910 waste pickers, providing economic livelihood.

1. Line 347-352:Is there any relevant solution strategy for the conflict of interest between Brazilian scavengers and the WtE industry? Please provide additional explanation

The conflict in interests was ongoing and unresolved in reference 53. Added “unresolved” to (old) line 347.

1. Lines 228-230: Indicate that the model did not compare renewable energy scenarios, and it is suggested to clearly explain how this deficiency affects the applicability of the conclusion in Australia.

Added sentence: This lack of direct comparison precludes informed decisions by policy makers about the optimum waste management policy choice that considers the full range of options.

1. Lines 374-380:The author only mentioned that the lack of samples in Australia may be due to the industry being in its infancy. It is suggested to add a discussion on whether this gap will weaken the feasibility of policy recommendations?

Point taken. (Old) lines 379-80: “Nevertheless, we can reasonably expect patterns identified in other developed countries (e.g. Europe, USA) to apply to Australia” covers this but amended to say instead: “Nevertheless, we can reasonably expect patterns identified in other developed countries (e.g. Europe, USA) to be cautiously applied to Australia.”.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The article presents a comprehensive analysis of renewable energy systems in the context of the urban environment, focusing on aspects of sustainable development. The authors conducted a literature review on various types of renewable energy sources (RES), their integration in urban spaces, and their impact on the environment, society, and economy. The main discussions focus on photovoltaics, wind energy, geothermal energy, and hybrid systems, as well as sustainability assessment tools, such as LCA (Life Cycle Assessment) and energy efficiency indicators.

The following strengths of the reviewed article are worth emphasizing:

• Comprehensiveness of the review. The authors have gathered and organized an impressive amount of scientific literature—85 items. The reviewed literature allowed for a broad spectrum of technologies and contexts of their application in cities.
• Structure and clarity. The article’s text is well-organized. It is divided into logical thematic sections, which facilitates tracking arguments and conclusions.
• Consideration of environmental, economic, and social aspects. The authors rightly point out that sustainable development is not only about ecology but also economic efficiency and social acceptance.
• Interdisciplinary approach. The integration of engineering, environmental, and urban planning perspectives makes the work valuable for a wide audience.

The weaker points of the article are:

• The article is purely a review, without new empirical data or original analytical models. Although this approach is acceptable in reviews, in my opinion, such a valuable article could be strengthened by including a few case studies. Introducing examples would increase the practical value of the work. However, I would like to add that the current form is already very good.
• Although the article mentions the global nature of the analysis, most of the examples discussed come from developed countries. There is a lack of a broader perspective on cities in developing countries, which face different infrastructure and social challenges. It would be good to include a few sentences about the situation in developing countries.
• The final conclusions are somewhat too general. There is a lack of stronger practical recommendations or suggestions regarding urban policy and energy planning.

In conclusion, the article provides a valuable overview of the current state of knowledge about RES systems in the urban environment from a sustainable development perspective. It can certainly serve as a starting point for further research and as educational material. However, to increase its impact, I would recommend supplementing the final version with empirical data, including specific case studies, and considering a broader geographical context.

Author Response

• The article is purely a review, without new empirical data or original analytical models. Although this approach is acceptable in reviews, in my opinion, such a valuable article could be strengthened by including a few case studies. Introducing examples would increase the practical value of the work. However, I would like to add that the current form is already very good.

Point taken. However, at this stage it is not practicable to carry out further work of a substantial nature.

• Although the article mentions the global nature of the analysis, most of the examples discussed come from developed countries. There is a lack of a broader perspective on cities in developing countries, which face different infrastructure and social challenges. It would be good to include a few sentences about the situation in developing countries.

We included global south and developing countries when they came up in the search. Further, the review is focused into the Australian context. We agree that there are differences in a variety of socioeconomic factors between global south and Australia. Given the Australian context however we think adding a perspective relating to cities in the global south to be a side issue.

• The final conclusions are somewhat too general. There is a lack of stronger practical recommendations or suggestions regarding urban policy and energy planning.

Point taken.

Revised final paragraph to the conclusion:

We predict ever diminishing economic and environmental benefits of WtE-I as the electricity grid becomes more renewable and as recycling becomes the predominant waste management strategy.^63,71

In the light of poor economic viability, unclear environmental outcomes, public health concerns and social justice issues, we recommend that:

1. WtE-I not be relied upon as a significant and enduring component of the energy supply and waste management in the Australian context;
2. Governments more proactively involve communities in waste management planning across the spectrum from reducing to disposal;
3. more progressive waste management strategies be adopted to facilitate the move towards renewable energy and waste minimisation, which have proven to be effective in other settings;⁵³
4. In particular, governments much more proactively engage with communities where waste management facilities are to be sited and be much more responsive to the concerns these communities may have.

 

Reviewer 3 Report

Comments and Suggestions for Authors

This paper shows, environmental, and sociopolitical results regarding the suitability of WtE-I, and are contingent on variables such as subsidies, land availability, specifics of WtE-I plant technology, MSW composition, the policy environment, availability of alternatives (e.g. reducing and recycling), and the extent to which the electricity grid is renewable. From the literature we find that the negative impacts of WtE-I outweigh the benefits. Social injustices persist in the form of increased exposure to toxins detrimental to human and ecological health in areas near WtE-I plant. For policymakers, there has been ongoing tension between the economic and GHG benefits of WtE-I and the grassroots opposition against WtE-I. Environmentally, WtE-I appears generally superior to landfill. Nevertheless, there are substantial concerns regarding toxic chemicals in flue gas, heavy metals in bottom ash, and air quality around plants. From an economic perspective, WtE-I has benefits under certain conditions, including economic superiority compared with landfill, as well as GHG emissions savings under the assumption of a fossil-fuel driven electricity grid. The high capital, operational and maintenance costs of WtE-I present a high barrier to entry. Funds that are currently allocated towards the development of a new WtE-I facilities may generate greater net benefit if allocated towards developing a reduction and recycling management approach or renewable energy infrastructure. In the light of poor economic viability, unclear environmental outcomes, public health concerns, and social justice issues, authors recommend that WtE-I not be relied upon as a significant and enduring component of the energy supply and waste management in the Australian context. Finally, authors recommend more progressive waste management strategies be adopted to facilitate the move towards renewable energy  and waste minimization, which have proven to be effective in other settings.

The paper content valuable data but it could be published after minor revision as below.

 

General Remarks

 

Abstract

Please do not use abbreviation in abstract or provide the full name.

 

Conclusions are too long and could be shorter at about 40-50%

 

 

Detailed remarks

 

1. Point 4.1.3. Examples of MSW detailed composition could be presented
2. Figures 1 should be self-explaining. Please add proper information.

Author Response

Abstract

Please do not use abbreviation in abstract or provide the full name.

The two abbreviations used in the Abstract are WtE-I and PRISMA.

We used WtE-I to reduce the word count for each use from four to one, saving 24 words and enabling more information to be included.

Use of PRISMA similarly saves five words. PRISMA is recognised abbreviation and is explained in the text.

 

Conclusions are too long and could be shorter at about 40-50%

We agree that the conclusion is long but given the level of detail and complexity in the paper we think it important to lay out a summary of the content in enough detail to help the readers remember and understand the important points that lead to the final recommendations.

 

Detailed remarks

 

1. Point 4.1.3. Examples of MSW detailed composition could be presented

Details added to lines 53-54 where the concept of MSW is first introduced. Replace “MSW includes diverse household discards” with “MSW is a very heterogenous fuel source and comprises organics (food and garden waste), recyclables (paper, plastics, metals and glass) and other materials (rubber, textiles, construction debris),”

 

1. Figures 1 should be self-explaining. Please add proper information.

 

Replacing “highlighting results of the methodology as applied in this study” with “describing search results and consequences of exclusion criteria leading to final articles reviewed”.

 

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript is clear, well-structured, and the topic is highly relevant.

The multi-dimensional approach adds value, and the review is methodologically sound.

I suggest slightly strengthening the connection to the Australian context and distinguishing short- and long-term recommendations more clearly. 

Author Response

I suggest slightly strengthening the connection to the Australian context and distinguishing short- and long-term recommendations more clearly. 

We think this is adequately covered in the Introduction. We have emphasised Australian context further in the Conclusion (in addition to revision as per suggestions by Reviewer 2).

 

Reviewer 5 Report

Comments and Suggestions for Authors

This is a very well-prepared article; however, the article did not bring something new of what is already known about the WTE incinerators. I guess this scoping review should be recruited properly within the Australian context. For example, if you get the waste composition of some Australian cities where the WTEI is intended to be launched, you can conduct some forecasting on the energy that can be generated. also discussing your findings in terms of land value in the relevant cities will also add to the Australian context.

Your scoping review should include some gray literature, governmental reports, and any industrial studies. for example, on what basis the government planning to launch new incinerators?

The review is well done as a review but is missing the Australian context to support the decision-making process.

The externality costs needs to be discussed in more details

provide a conceptual framework , problem statement, research implication to show how the economic, political and environmental aspects will impact the WTE Inc. decisionmaking process

Author Response

This is a very well-prepared article; however, the article did not bring something new of what is already known about the WTE incinerators. I guess this scoping review should be recruited properly within the Australian context. For example, if you get the waste composition of some Australian cities where the WTEI is intended to be launched, you can conduct some forecasting on the energy that can be generated. also discussing your findings in terms of land value in the relevant cities will also add to the Australian context.

 

This would be useful and interesting but would constitute original research and would need to be considered as a separate prospective research project. Our focus was on a scoping review to discover and summarise what is already known to feed into the Australian waste management policy discussion. For example the suggestion of energy forecasting is what some of the literature we scoped do themselves, and would necessitate quite a different (mathematical modelling) approach, skillset, etc to our scoping review we present here.

 

 

Your scoping review should include some gray literature, governmental reports, and any industrial studies. for example, on what basis the government planning to launch new incinerators?

 

We agree that additional literature would’ve been valuable to include in our review. We have not included any grey literature; our analysis only included peer reviewed literature from our Scopus search. The workload would have been too onerous for our small team to broaden the search criteria any more, and risk non-compliance with the PRISMA protocol.

 

In regard to “on what basis the government planning to launch new incinerators?“ This is a question for government, and is not addressed in the article because it’s not in our scope. We’ve mentioned that its part of the policy mix.

 

 

The review is well done as a review but is missing the Australian context to support the decision-making process.

 

Addressed in responses and alterations related to Reviewers 2 and 4.

 

The externality costs needs to be discussed in more details

 

Assuming the reviewer means “negative externalities”, if so we have talked about environmental externalities and economic perverse incentives at length. We can only discuss the result that we found from our literature search; if we haven’t talked about a particular externality it is because it didn’t come up in our search.

 

provide a conceptual framework , problem statement, research implication to show how the economic, political and environmental aspects will impact the WTE Inc. decision making process

 

We are not clear what the reviewer means by providing a conceptual framework in this context.

 

We have added this statement to the introduction:

 

The problem we address is the poor government engagement of communities where facilities are to be built and the seeming policy confusion at government level between waste minimisation/ circular economy development and the need to reduce greenhouse gas (GHG) emissions; our contribution to this conversation is to pull out and highlight some of the pertinent issues that need to be considered by the community and governments.

 

Implications for WTE Inc. decision making is addressed in the revised Conclusion.

 

Round 2

Reviewer 5 Report

Comments and Suggestions for Authors

The author did not address the first 2 points of my feedback. I think the main objective of the paper, as per the author's claim, is to examine the economic, environmental, and sociopolitical aspects of waste-to-energy incineration (WtE-I) and to provide recommendations for the Australian context. To be honest, I do not see any contextualization to the Australian context. as long as the scoping review is done to help the Australian government, then we need to consider the gray literature from other sources within australia to help us contextualize the review to Australia.

For example, the author wrote, The results are equivocal regarding the suitability of WeE-I and are contingent on variables such as subsidies, land availability, specifics of WtE plant technology.... I think if this paper is aiming to consider the Australian context, then this should have been discussed in more detail. 

The only strength in a scoping paper on waste-to-energy incinerators is the contextualization to a specific country or geographic location; failing to do so means that the scoping study did not achieve its goal.

The author's discussion and conclusion should be based on Australia.

There are many gaps even in conclusions; for example, funds that are currently allocated towards the development of a new WtE-I facility may generate greater net benefit if allocated towards developing a reduction and recycling management approach or renewable energy infrastructure. This statement needs to be supported with findings within the discussion of the review.

 

Author Response

Reviewer 5’s follow on comments are noted.

I agree that not looking at the grey literature may have missed some aspects of the situation in Australia. I have added a fifth limitation to cover this: “Omission of grey literature from our search may have missed some relevant aspects that may have contributed to the discussion”.

We have tried to put the paper in an Australian context; for instance see lines 72 to 88, and in the conclusions.

Regarding the opportunity costs of WtE, see line 441 “Funds that are currently allocated towards the development of a new WtE-I facilities may generate greater net benefit if allocated towards developing a reduction and recycling management approach or renewable energy infrastructure.”

Overall however, while Reviewer 5 has made valuable points, the reality is that the research team has disbanded and we have no capacity to carry out additional search work and input additional aspects to the article. This particularly applies in the context of the rapid turnaround asked for response to this review.