A Framework to Assess the Resilience of Energy Systems Based on Quantitative Indicators

Round 1

Reviewer 1 Report

Overview: I appreciate the opportunity to review this manuscript describing a proposed energy resilience framework and associated modeling. It is my opinion that this paper requires major revision before further consideration for publication.  My comments are included below, and are focused on addressing unclear aspects of the paper to better understand the origin of various components as well as the methodologies and data sources utilized.

Data statement: The data availability statement (line 917) is listed as “not applicable.” However, there was a model used and clearly data driving the model (both inputs and outputs). Please clarify and provide relevant data links or files per the journal’s requirements.

Section 2 (Energy system resilience indicators) - General:  No information is provided on how the proposed resilience indicators were developed.  The credibility of a resilience framework is at least partially dependent on how the framework was built.  The paper should describe any process (or lack thereof) so that readers understand how the proposed framework was developed and why the authors are proposing the indicators (and thresholds within) described in the paper as opposed to possible alternates.  For example, were energy system experts consulted or surveyed? Were past energy system failures analyzed for common points of failure? Were existing standards expanded upon? Something else?

Section 2 (Energy system resilience indicators) – General: For each of the indicators proposed, is there any evidence pointing to the importance of proposed indicators in assessing resilience prior to developing the models? For example, for I1, are there documented known challenges with too few entry points into the energy system?  The same applies throughout as most of the indicators have no evidence presented with them.

I1 (Number of Entry Points): It is unclear how this indicator is quantified.  That is to say, is a system with two entry points twice as resilient as a system with one entry point? Is one with four entry points similarly twice as resilient as one with two? This is implied by the description, and if not intended should be clarified.

I1 (Number of Entry Points): The example provided in 137-144 is all one fuel system.  How does this assessment change if only some of the electricity system runs on natural gas, and some on other fuels not subject to the same entry points?

I2 (Number of electricity import sources): What qualifies as an “import source” in this context? Does the origin of the import (either distance or country’s status as being on good or less than good terms) matter? It is unclear whether this indicator is saying that more import sources is likely to be more resilient or fewer import sources is likely to be more resilient (with the implication that more sources would then be domestic.)

I3: Although having more generators would seem to be intuitively more resilient, is there evidence to support this? Is there a balance that has to be made recognizing that too many generators adds to system complexity and potentially more points of failure (and fewer economies of scale for generator-side resilience)? Similar arguments can be made for several of the other indicators.

I4 and I5: Why is the electricity transmission measured in “number” of lines versus pipelines which are measured in “capacity”?  As electrical transmission lines also have capacities, wouldn’t it be better to compare on similar terms if possible?

I6 and I7: The implication with these indicators is that a greater length of transmission lines or pipelines increases system resilience.  However, there is no mention that longer lines/pipelines also means that there are more potential points of failure, the energy source is further from its point of use, and lengthy systems are inherently more complex and more difficult to replace on an emergency basis with other transport methods.

I9: It is unclear what is measured in the “configuration of the energy systems”

I11: An energy system with a greater amount of distributed generation is not necessarily more resilient than more centralized systems.  In order to utilize distributed generation, micro-gridding would be required and it would be necessary to match supplies to demand within these mini-systems.  This is considerably more complex and not readily available for most generation today to be a useful indicator in the way it is currently described.

I12: This indicator seems to measure only the number of spare parts and not the diversity of said parts.  At a certain point, additional supplies of some parts will not increase resilience meaningfully because it is unlikely they will be needed over a reasonable period of time.  Instead, matching the spare parts inventory to projected needs is likely to yield far more resilience than simply trying to have a larger number of total parts.

Diversity indicator 1 and 2: It is unclear how these two indicators are different

Diversity indicator 3(a): Is it unclear what a “technology group” is in this context.

Line 334: Please provide at least a general overview of what is being measured in the indices presented here.

Lines 402-404: Although there are many other indicators that likely have an inflection point where resilience is either no longer increases or may actually decrease, these lines are the first time in this paper where I’ve seen such a consideration discussed.

I20: Wouldn’t a fuel cost change impact both the numerator (fuel cost) and the denominator (total costs)? How would this impact the indicator?

I21: Please define “final energy demand” in this context.

I24: I an considered that in actual practice (where a resilience index would be used) it may not be possible to know differential costs of a baseline scenario versus a changed scenario.

I25: This indicator makes little sense absent a threshold or other method of putting it into context, as virtually every piece of equipment within an electricity system is critical to someone.

Author Response

Responses are provided in the attached file

Author Response File: Author Response.docx

Reviewer 2 Report

The paper “Framework to Assess Resilience of Energy Systems by Quantitative Indicators“ describes the solution of the energetic system in the EU and the possibility of quantitative monitoring of it. The topic is extremely significant, especially within the framework of the war in Ukraine.

The introductory part of the paper provides a sufficient background. The references list is clearly stated, but the literature review should be supplemented by a more detailed analysis of relevant scientific research and papers published over the past few years.

The analysis of the legislative framework is somewhat more detailed, but the European Green Plan should also be considered as a key document with further changes in both the development and energy fields.

The research design of the paper is good, and the explanation of the methods used adequately. Results of the research are clearly presented.

Conclusions of the paper are supported by results and they are fairly clear and concise. However, since resilience as a topic requires a holistic evaluation approach, it was necessary to open up the issues of qualitative evaluation, not quantitative, and to emphasize that such research will need to be conducted in the future in order to obtain a complete picture.

Author Response

Responses are provided in the attached file.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Overview: I appreciate the opportunity to rereview this manuscript describing a proposed energy resilience framework and associated modeling. I have reviewed the revised manuscript and the response to authors.  The authors have considerably improved the manuscript through revision, including a more detailed account of the context, background, and limitations of the present study.  I believe this paper is now appropriate for publication.