Greater Energy Independence with Sustainable Steel Production

Reviewer 1 Questions

Author comment

Manuscript line no.

1. What are the principal outcomes related to CO₂ emission reductions from employing sustainable methods in steel manufacturing compared to conventional practices?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

Abstract: Global energy market price volatility and an upward trajectory of prices per unit of electricity have sent all industrial sectors and many economies to the brink of recession. Alongside the urgent need for decarbonisation of all industries, achieving a globally higher level of energy independence across all sectors seems imperative. A multi-disciplinary approach with a proposed system of CO₂ emissions reduction and capture technologies has the potential for short-term emissions reduction to near-zero in the steel industry – although some of the mechanisms can be implemented across most heavy industries. The findings of this research showed CO₂ emissions reduction of ~30% from 977t of CO₂ to 684t in one single blast furnace production cycle (based on 330 tonnes liquid iron production capacity, with the mean of 2.1-3.2 tonnes CO₂/t of steel and chemical reactions emissions applied), by switching the electricity provider for operating the electric heaters to providers generating energy exclusively from renewable sources. Replacing coal with biomass, and adding post-combustion capture units to the blast furnace operation, will add carbon neutrality into the process - resulting in CO₂ emissions reduction to near-zero. Carbon capture from biomass utilisation (BECCS) will add the benefit of carbon negative emissions to the cycle.

Line 7-20 Page 1

2. How does the use of renewable energy sources like solar PV panels influence the overall energy autonomy of the steel production processes described?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

Energy-saving and process improvement measures implementation (up to 60% efficiency increase), excess heat recovery (<30% of energy savings) and retrofitting renewable energy technology resulted in an energy independence of 88%. Short-term engineering solutions, partly subsidised in the UK, are readily available. Further detailed information has been provided in tables 1 and 2.

Line 20-24 Page 1

3. Within the discussion, how do the authors tackle the hurdles and potential constraints of globally expanding the suggested sustainable steel production techniques?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

There are 2 major hurdles to the implementation of sustainable steel production techniques: 1) willingness across all industries to do so and 2) financing all efforts using appropriate MCDA and costings. Hurdle 1) relies on industry to do what needs to be one to avert climate disaster, as our politicians worldwide seem to lack the political willingness to implement and enforce adequate policies  – the signs are all around us. The author is continuing to research and campaign in this direction. Hurdle 2) has been partly addressed by governments across the globe and the UK government with grants, loans and subsidies, which I referred to in my manuscript. I mentioned this at various points in my manuscript:

Conclusions - Achieving a higher degree of energy independence is within reach of all sectors of society, made possible by technological progress and incentives and grants provided by the respective governments and countries, including the UK. The opportunities are manifold, they merely require political willingness and implementation across all industries.

Line 64-74 Page 2 and

Line 401-423 Page 13/14

4. What methodologies were used to evaluate the economic and environmental impacts of adopting these renewable energy technologies? Can you provide a detailed comparative analysis of the costs, savings, and ROI associated with each technology, as well as their respective impacts on carbon emissions reduction and energy independence?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

A thorough MCDA has been carried out, please see: ‘Table 2: MCDA excerpt implementation details and cost.’ As already mentioned, the CO₂ emissions can be reduced to almost zero: “Abstract ….~30% reduction, to 335 tonnes CO₂e. Finally, the installation of CO₂ capture technology reduced the CO₂ emissions to near-zero.” This has been further highlighted in the text: Renewable energy technology is market ready – now the implementation is key.

The choice and implementation of any of these technologies are entirely dependent on the individual site parameters and need to be thoroughly assessed with regard to their suita-bility for the identified location, and viability with an outlook over the next 30 years. The  accurate potential ROI (return on investment) can only be determined for every individual site, as the current contracts with energy providers are one of the determining factors and the authors have not been privy to this kind of information.  The MCDA in Table 2 in-cludes service and maintenance time and cost, the likelihood of repairs and the availabil-ity of suitable service providers to carry out said repairs, servicing and maintenance. Pro-jections for policy making, return over investment (ROI) or how this could lead to the de-velopment of new incentives in the realm of renewable energy and sustainable industrial practices was not the substance of this research. Some examples in Table 2.

Line 7-19 Page 1 and

Line 337-341 Page 12

Line 141-142 

Page 5

5. How do the proposed renewable energy solutions align with current UK government incentives and energy efficiency schemes, particularly in terms of eligibility criteria and potential benefits? Is there evidence or projections on how these technologies could influence future policy-making or lead to the development of new incentives in the realm of renewable energy and sustainable industrial practices?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

The scheme descriptions in: ‘Table 1: UK support schemes renewable energy technologies’ provide details on the eligibility criteria and potential benefits. Projections for policy making or how this could lead to the development of new incentives in the realm of renewable energy and sustainable industrial practices was not the substance of this research, as in the current global political climate, all projections must be seen as wishful thinking. There are more wars currently underway than 500 years ago, with more sophisticated weaponry than ever before (war is still a good business model, it seems), as political diplomacy leading to peace, or the creation and implementation of climate disaster averting policy, do not seem to be high on the agenda in most countries observed.

Line 308-324 Page 9/10

6. Given the claim of capturing over 98% of CO₂ emissions, can you 6.1) elaborate on the practical challenges and long-term sustainability of this approach? 6.2) How does the utilization of captured CO₂ in ancillary industries contribute to overall emission reductions, and are there any 6.3) notable examples or case studies that demonstrate this effectiveness?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

6.1) There are 2 major hurdles to the implementation of sustainable steel production techniques: 1) Willingness across all industries to do so and 2) Financing all efforts with appropriate MCDA and costings. Hurdle 1) Relies on industry to do what needs to be one to avert climate disaster, as our politicians worldwide seem to lack the political willingness to implement and enforce adequate policies  – the signs are all around us. The author is continuing to research and campaign in this direction. Hurdle 2) has been partly addressed by governments across the globe and the UK government with grants, loans and subsidies, which I referred to in my manuscript. I mentioned this at various points in my manuscript: Conclusions - Achieving a higher degree of energy independence is within reach of all sectors of society, made possible by technological progress and incentives and grants provided by the respective governments and countries, besides the UK. The opportunities are manifold, they merely require political willingness and implementation across all industries.

6.2) The utilization of captured CO₂ in ancillary industries contribute to overall emission reductions potentially to the same percentage, as stated in the manuscript, last paragraph before Conclusions: “The CO₂ emissions by industry sector were analysed [33,39,54–57] and besides the iron and steel industry, there are other heavy industries which are CO₂ emitters, and generating copious amounts of off-heat, co-products and therewith resources, which could be harvested and used to power energy-dependent devices: Transport, Chemical industry, Energy Supply, Residential/Commercial buildings sector, Agriculture, and Waste Management.”

6.3) Even before the IPCC (2021, 2022, 2023) have issued stark warnings, industry leaders have realised their responsibilities and have started globally 89 projects with the aim to establish technologies which have the potential to decarbonise heavy industry, and not only the steel industry. Link: https://www.industrytransition.org/green-steel-tracker/  and 20231123-green-steel-tracker.xlsx (live.com)

Line 64-74 Page 2 and

Line 401-417 Pages 12/13

7. 1) Considering the increasing global electricity consumption and the implementation of renewable energy resources like solar, wind, and hydro, how significant is the impact of these renewable sources on reversing or stabilizing these consumption trends? 7.2) Is there data or modeling that quantifies the potential reduction in electricity consumption attributable to renewable energy adoption, especially in high-demand countries like China?

8. The text mentions the potential of saving energy by making existing infrastructure more efficient and reducing energy/heat loss. Could you provide more details on the specific 8.1) strategies and 8.2) technologies that are considered most effective for this purpose? Additionally, how does this approach compare in terms of 8.3) cost and  8.4) impact with the installation of new renewable energy infrastructures?

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

7.1) This manuscript only dealt with the technical solutions currently available for the decarbonisation of the steel industry and how decarbonisation could lead to a higher degree of energy independence, based on the current energy consumption. The consumption trend evaluation or influence of renewables implementation on consumption trends of renewables implementation on a global scale cannot be determined, as these are two completely independent, separate issues altogether, but pose an interesting challenge for future research. I have some data in this regard, as I was hoping this very question could also potentially be answered in the manuscript, but without reliable Chinese government-approved data, and with China setting new records in renewables installation almost on a monthly basis, it would be presumptuous of me to attempt any such projection.

7.2) This research focuses on the steel industry only. China is the world leader in terms of renewables installation and seems on an upward trajectory of replacing fossil fuel-based energy generation with renewable energy technology.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

8.1) The strategy for making existing infrastructure more efficient is to a) upgrade the existing energy infrastructure b) Reducing energy/heat loss by improving energy efficiency with focused energy utilisation, c) capture and re-utilise lost energy/heat.

8.2) The technologies utilised for the strategy points a-c, as follows:

a) Repair energy/heat escape points and insulate as preventive measure;

b) Using the most focused technology: instead of the blast furnace/basic oxygen furnace-route, using the blast furnace/electric arc furnace route for steel production;

c) Installation of baffles, plate heat exchangers and other energy/heat capturing technology where technically feasible.

8.3) Please see the MCDA in Table 2.

8.4) The first column demonstrates the emission levels in metric tonnes (t) as per legend underneath from BF/BOF average value in CO₂ emissions, the reduced level of CO₂ emissions after switching to an energy provider deriving their energy at 100% from renewable sources, the reduced level of CO₂ emissions after replacing coal with biomass in the BF, the reduced level of CO₂ emissions after installation of renewable energy technologies (solar, wind, hydro as appropriate), and the reduced level of CO₂ emissions after the installation of post-combustion CO₂ emissions filters. The second column shows the individual per-centage proportion in reduction as a result of implementation. The third column shows the successive percentage increase in energy independence. The fourth column shows the successive change of CO₂ emissions in t, based on one cycle of a 330t BF/BOF process. The fifth column shows the remainder of the CO₂ emissions after successive implementation of the suggested technologies – resulting in 0.18t of CO₂ emissions, but displaying as 0 due to set software parameters, after successful installation of post-combustion CO₂ filters at the individual sites of off-gas outlets.

Line 42-47 Page 1

7.2) Line 43-45 Page 1

8.1) Line 193-196 Page 7

8.2) Line 201-207 Page 8

8.3) Line 337-339 Page 12

8.4) Line 163-180 Page 7

Reviewer 2 Questions

Author comment

Manuscript line no.

1. In introduction section, the purpose of the work presented as well as the global overview is missing.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

Numerous countries are on the brink of recession across geographical Europe at the time of writing, and energy price increases have made a strong case for the urgent need to achieve greater energy independence – the demonstration of the feasibility being the purpose of this paper.

Line 30-34 Page 1

2.a But What is the most important approach for presenting the work done? The way of assessing the scientific contribution of the work done is different when proposing a literature review vs proposing scientific research.  

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text: The scientific contribution as a result of scientific research, with a literature review only being part of the study, has been presented following data dissection via taking a pentagonal approach, as described in the image below.

2. Materials and Methods

Throughout this project, global data in connection with renewable energy technology implementation in different settings has been utilised [9–14]. Information on factual CO2 emissions in steel production [15] and manufacturing [16–18] have been considered, as well as data from other industrial sectors [4,9,19–21]. In order to visualise the opportunities of a circular steel production process, implementation of sustainable elements and opportunities for achieving great energy independence, a comprehensive steel manufacturing overview has been compiled, as displayed in Figure 1. The data was accumulated, analysed and used for modelling using MS Excel and simultaneously analysed by applying standard mathematical principles and followed for proof of concept with steel production simulations in Simul8, Inosim and Aspen.

The data has been gathered and utilised via the approach, described, as follows:

The scientific approach of presenting findings in a transparent and replicable manner have been adhered to, throughout.

Line 51-180 Page 1-7

2.b) My recommendation is to inverse order of presenting the info in the paper: 1st literature review and 2nd modelling for confirming and validation. I would suggest describing deeper the modeling and simulation part since this is the differential contribution of the paper.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

The literature review was the first step of the scientific research and the results of which were  therefore presented first within a 5-step-approach (see above).

2. Materials and Methods

Literature Review:

Throughout this project, global data in connection with renewable energy technology implementation in different settings has been utilised [9–14]. Information on factual CO2 emissions in steel production [15] and manufacturing [16–18] have been considered, as well as data from other industrial sectors [4,9,19–21]. In order to visualise the opportunities of a circular steel production process, implementation of sustainable elements and opportunities for achieving great energy independence, a comprehensive steel manufacturing overview has been compiled, as displayed in Figure 1.

Simulations:

The data was accumulated, analysed and used for modelling using MS Excel and simultaneously analysed by applying standard mathematical principles and followed for proof of concept with steel production simulations in Simul8, Inosim and Aspen.

Line 51-180 Page 1-7

2.c) Fig 4 may result a little bit confusing since figures (bars) are offering different concepts and numbers are mixing % with T of CO₂. I would suggest to better explain this figure in the text.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

The simulation results are detailed in metric tonnes, occurring during one production cycle, based on 330 metric tonnes BF and BOF furnaces. The first column demonstrates the emission levels in metric tonnes (t) as per legend underneath from BF/BOF average value in CO2 emissions, the reduced level of CO2 emissions after switching to an energy provider deriving their energy at 100% from renewable sources, the reduced level of CO2 emissions after replacing coal with biomass in the BF, reduced level of CO2 emissions after installation of renewable energy technologies (solar, wind, hydro as appropriate), reduced level of CO2 emissions after the installation of post-combustion CO2 emissions filters. The second column shows the individual percentage proportion in reduction as a result of implementation. The third column shows the successive percentage increase in energy independence. The fourth column shows the successive change of CO2 emissions in t, based on one cycle of a 330t BF/BOF process. The fifth column shows the remainder of the CO2 emissions after successive implementation of the suggested technologies – resulting in 0.18t of CO2 emissions, but displaying as 0 due to set software parameters, after successful installation of post-combustion CO2 filters at the individual sites of off-gas outlets.

Line 163-180 Page 7

d) “Renewable energy technology is market ready” but an explanation of the reason for not having industrial references in steel industry is needed.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

The MCDA, presented as an excerpt in Table 2, gives information to that effect.

There are currently 89 projects underway to support the decarbonisation of the steel industry.

Industrial references in steel industry have been utilised, throughout.

There are currently 2 hurdles preventing renewables implementation in the steel industry: political willingness and the funding to do so.

Line 337-341 Page 12

Line 422-423 Page 14

Line 475-645 Page 15-18

Line 64-74 Page 2

Reviewer 3 Questions

Author comment

Manuscript line no.

2) Yet, in the introduction, the authors didn’t provide any information regarding the steel industry in UK and mentioning GHGs emissions in China instead. This intro seems rather irrelevant to their topics.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

In reply to this question, please see the text passage, below – it includes global data [ref. 1-8], not confined to UK or China. Also, throughout the introduction, reference has been made to global data. The referenced resources will provide more details:

1. Introduction

The volatility of the global energy market and recent price-hikes by energy producers have caused never-before-seen levels of profit for the energy companies, and untold pressures for businesses and the population in most developed economies. Numerous countries are on the brink of recession across geographical Europe at the time of writing, and energy price increases have made a strong case for the urgent need to achieve greater energy independence. This could be considered one of the foremost important contemporary endeavours. The iron and steel industry, along with heavy industry and petroleum refineries [1], are by far the largest emitters of CO2 emissions, due to their high energy demand. The steel industry is accounting for between 7% and 11% [1–7] of global CO2 emissions as a result of steelmaking, and China is responsible for 50% of these GHGs [7], due to their heavy reliance on coal. The increased use of coal in energy generation, due to imposed oil and gas shortages, was found to be the main factor [1,8] driving up global energy-related anthropogenic CO2 emissions by over 2 billion tonnes, their largest ever rise in absolute terms.

References

1.             IEA (International Energy Agency). IEA. 2023 [cited 2023 Jul 7]. IEA Data and Statistics. Available from: https://www.iea.org/data-and-statistics

2.             Baena-Moreno F, Cid-Castello N, Arellano-García H, Reina T. Towards emissions free steel manufacturing – Exploring the advantages of a CO2 methanation unit to minimize CO2 emissions. Science of The Total Environment. 2021;781(7):Article ID 146776.

3.             Hasanbeigi A. Steel Climate Impact—An International Benchmarking of Energy and CO2 Intensities [Internet]. 2022 [cited 2023 Jul 7] p. 2. Available from: https://static1.squarespace.com/static/5877e86f9de4bb8bce72105c/t/624ebc5e1f5e2f3078c53a07/1649327229553/Steel+climate+impact-benchmarking+report+7April2022.pdf

4.             COM (European Commission). CORDIS | European Commission. [cited 2023 Jul 6]. Steel industry boost research into cleaner technologies. Available from: https://cordis.europa.eu/article/id/29184-steel-industry-boost-research-into-cleaner-technologies

5.             IEA (International Energy Agency). Data and Statistics [Internet]. 2021. Available from: https://www.iea.org/data-and-statistics/data-browser?country=WORLD&fuel=Energy%20transition%20indicators&indicator=ETISharesInPowerGen

6.             Swalec C. Carbon Brief. 2021 [cited 2023 Jul 7]. Guest post: These 553 steel plants are responsible for 9% of global CO2 emissions. Available from: https://www.carbonbrief.org/guest-post-these-553-steel-plants-are-responsible-for-9-of-global-co2-emissions/

7.             Ren L, Zhou S, Peng T, Ou X. A review of CO2 emissions reduction technologies and low-carbon development in the iron and steel industry focusing on China. Renewable and Sustainable Energy Reviews. 2021 Jun;143:110846.

8.             IEA (International Energy Agency). IEA. 2018 [cited 2023 Jul 7]. Global energy demand grew by 2.1% in 2017, and carbon emissions rose for the first time since 2014 - News. Available from: https://www.iea.org/news/global-energy-demand-grew-by-21-in-2017-and-carbon-emissions-rose-for-the-first-time-since-2014

Line 27-42 Page 1

Line 475-498 Page 15

3) In addition, in the materials and methods sections, it would be clearer, if the authors could have listed the sources of the data to show the authority of the data sources and divided them into the categories included in the following paper.

Thank you for your feedback.

The publishers have a set format for their articles and a grouping, and as the reviewer suggested, would not adhere to the publisher’s formatting requirements, i.e. how to display the references.

Line 475-645 Page 15-18

4) Based on the paper’s discussion, reducing CO₂ emission and its negative environmental impact would not be impossible to start applying these methods in the real steel industry.

Thank you for your feedback. Your feedback has resulted in the modifications made as presented in the following text:

There are already 89 projects worldwide underway, advancing the technologies and processes suggested in this paper. They can be found at https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fwww.industrytransition.org%2Fcontent%2Fuploads%2F2023%2F11%2F20231123-green-steel-tracker.xlsx&wdOrigin=BROWSELINK  and are being carried out by the great and good of the steel industry, with the aim to achieve climate neutrality latest by 2050.

Hence this paper, as a result of research focused on decarbonisation of the steel industry, aimed to highlight the incredible opportunities of renewables implementation and excess heat recovery, as well as achieving a higher degree of energy independence at the same time. This data is referenced in the updated version of the manuscript.

Line 422-423 Paage 14