Assessing the Costs of Commercialising Tidal Energy in the UK

Round 1

Reviewer 1 Report

The paper delves into harnessing tidal turbine technology to tap into predictable tidal energy, aiming to increase renewable energy supply to achieve net-zero goals and economic decarbonization. While your paper explores an interesting topic, it still has some problems. We have identified several key issues that need to be addressed:

1.The paper mentions tidal energy as an emerging technology and introduces the current state of energy utilization in the UK. However, it lacks an overview of the global development status and prospects of this technology. It is suggested to provide more background information in the introduction section to help readers better understand the research context and significance.

2.The paper conducts sensitivity analysis on investment requirements. Common sensitivity analysis methods include parameter sensitivity analysis, scenario analysis, and Monte Carlo simulation, used to assess the sensitivity of model outputs to changes in input parameters. It is recommended to detail the specific analysis methods and models employed to enhance the credibility and reproducibility of the study.

3.The paper mentions strategies to achieve cost reduction through subsidy deployment and research innovation. However, the implementation of these strategies may face issues such as policy uncertainty. Therefore, it is suggested to further analyze and evaluate these strategies in the conclusion or discussion section.

Minor editing of English language required

Author Response

We are glad you find the topic interesting and thank you for your insightful comments to help improve the clarity and quality of our draft manuscript. Please find responses to your specific points below. The corresponding revisions are highlighted with blue track changes in the re-submitted files.

1.The paper mentions tidal energy as an emerging technology and introduces the current state of energy utilization in the UK. However, it lacks an overview of the global development status and prospects of this technology. It is suggested to provide more background information in the introduction section to help readers better understand the research context and significance.

Response 1: Your suggestion to add further context on status and prospects is valuable, and we have tried to include this within the introduction as advised based on recent international reports by IRENA & IEA-OES.

2.The paper conducts sensitivity analysis on investment requirements. Common sensitivity analysis methods include parameter sensitivity analysis, scenario analysis, and Monte Carlo simulation, used to assess the sensitivity of model outputs to changes in input parameters. It is recommended to detail the specific analysis methods and models employed to enhance the credibility and reproducibility of the study.

Response 2:  We have clarified that we have used a targeted scenario analysis investigating key parameters with credible ranges to better understand the relationship between model inputs and outputs, and to show what most influences the overall investment required.

3.The paper mentions strategies to achieve cost reduction through subsidy deployment and research innovation. However, the implementation of these strategies may face issues such as policy uncertainty. Therefore, it is suggested to further analyze and evaluate these strategies in the conclusion or discussion section.

Response 3:  Policy uncertainty is a legitimate concern, and this has now explicitly been mentioned at the end of the discussion section. While it is not the focus of the paper to assess the effectiveness or otherwise of different policy mechanisms and their implementation, this is reflected within the range of scenarios investigated.

Reviewer 2 Report

The manuscript subject “Assessing the Costs of Commercialising Tidal Energy in the UK” is interesting. However, the article needs to be improved. In details: 

1.       The renewable energy market share for each type of renewable energy such as wind, biomass, solar, etc. in the UK can be discussed for a better understanding importance of each technology especially tidal energy in the UK. 

2.       In Figure 1 offshore and onshore wind energy electricity production trends are shown and they are considered for the estimation of electricity production of tidal stream. It is better to consider the other renewable energy electricity production trends besides wind energy for better estimation of tidal energy electricity production trends. Also, it is observable in the figure the trend of tidal energy had slower development in comparison with wind energy and the estimation is a little unrealistic. 

3.       In section 2.3., the relation between historical learning rates for other renewable energy technologies and tidal energy is unclear and should be discussed and explained better. 

4.       In lines 240 and 241 it is mentioned “We assume a similar rapid growth is observed for tidal stream in the UK as has been observed in other technologies, see Section 2.1.”  this assumption should be explained and discussed better as it is mentioned in previous comments.

 5.       In lines 251 and 252 “Around 0.9 GW in 2035, based on the UK Marine Energy Council target of 1 GW of ocean energy by 2035, assuming the majority of this will be from tidal stream, with the remainder coming from wave energy deployments” it is assumed that the majority of the 1 GW target will be form tidal stream. The share of wave energy and tidal streams of this target can be mentioned.

6.       The article just discusses economic aspects and market analysis of tidal energy in the UK and may not be well match to be published in Energies.

Author Response

We are glad you find the topic interesting and thank you for your insightful comments to help improve the clarity and quality of our draft manuscript. Please find responses to your specific points below. The corresponding revisions are highlighted with blue track changes in the re-submitted files.

1. The renewable energy market share for each type of renewable energy such as wind, biomass, solar, etc. in the UK can be discussed for a better understanding importance of each technology especially tidal energy in the UK.

Response 1. A table with the National Grid FES2023 projections for various technologies has been included for context. While doing this, a minor mistake in the share of tidal with respect to the total installed capacity was also corrected, and the 2035 share was removed for brevity.

2. In Figure 1 offshore and onshore wind energy electricity production trends are shown and they are considered for the estimation of electricity production of tidal stream. It is better to consider the other renewable energy electricity production trends besides wind energy for better estimation of tidal energy electricity production trends. Also, it is observable in the figure the trend of tidal energy had slower development in comparison with wind energy and the estimation is a little unrealistic.

Response 2. The deployment trajectory is based on annual deployment (GW) not energy production (GWh). Solar PV has been added to Figure 1, however as this has seen many billions of small-scale panels installed, this may not be the most appropriate comparison for tidal stream, which has been noted. Other renewable energy technologies have not seen such rapid growth, and this has also been noted. Additionally, there was limited market support for tidal energy in the period 2017 to 2025, which resulted in few deployments. The deployment rate is also less consistent when considering few individual projects at the start, but there is now a pipeline of projects in the UK & France which shows a similar growth potential to wind. Finally, this is not a prediction of what will happen, but an ambitious scenario of what could happen, and the funding required to enable this, which has also been revised to hopefully clarify this.

3. In section 2.3., the relation between historical learning rates for other renewable energy technologies and tidal energy is unclear and should be discussed and explained better.

Response 3. We have tried to clarify that these historical learning rates are used as examples to give context and guide our assumptions for what could happen in tidal stream, which are set out later in Section 3.1.2.

4. In lines 240 and 241 it is mentioned “We assume a similar rapid growth is observed for tidal stream in the UK as has been observed in other technologies, see Section 2.1.” this assumption should be explained and discussed better as it is mentioned in previous comments.

Response 4. As mentioned in response to the related point 2, this has hopefully been clarified in the revised draft.

5. In lines 251 and 252 “Around 0.9 GW in 2035, based on the UK Marine Energy Council target of 1 GW of ocean energy by 2035, assuming the majority of this will be from tidal stream, with the remainder coming from wave energy deployments” it is assumed that the majority of the 1 GW target will be form tidal stream. The share of wave energy and tidal streams of this target can be mentioned.

Response 5. There is currently uncertainty in the size and make up of a sector deployment target. The paper has been updated to clarify that it is actually only an ask for a target from the Marine Energy Council. The tidal deployments for 2035 and 2036 are included, and the supplementary table mentioned in the text to make this clearer.

6. The article just discusses economic aspects and market analysis of tidal energy in the UK and may not be well match to be published in Energies.

Response 6. We have clarified that while this focuses on the specific case of tidal energy in the UK, the overarching points are applicable to other countries/markets and renewable energy technologies, and as such we think this will be of interest to a wider audience, and fits within the broad scope of work published in Energies.