Multicriteria Definition of Small-Scale Biorefineries Based on a Statistical Classification

Round 1

Reviewer 1 Report

By the present study the authors present a multicriteria methodology to define small scale biorefineries. Data obtained from operational biorefineries are analyzed using a multivariate analysis combined with a hierarchical clustering.

To this aim, in the Methods section, the authors present well developed and described methodology consisting of four steps to generate the classification of biorefineries.

The method is then applied to a dataset obtained by 24 biorefinery projects leading to analyze data from 15 operational biorefineries.

However, the steps presented in the Methods are not specifically followed in the presentation of the Results, so that the reader is prevented to follow the developing of the applied methodology. Instead, the presentation of the Results is confusing and even more owing to they are presented in a single Results and Discussion section.

Finally, a quite short and generic paragraph of Conclusion ends the manuscript completely missing a perspective for future analysis as well as an analysis of the limitation of the study.

Based on these points, this reviewer rises the following criticisms:

• First, how the authors can demonstrate that the number of biorefineries, 15, where they obtain the data, is consistent with a significative multivariate analysis? This point was never considered in the manuscript.
• Results and Discussion must be presented in separated sections. Then, the results must be presented specifically following the same steps shown in the Methods, so that the reader can easily follow the realization and the developing of the methodology.
• Following the Discussion, a wider Conclusion capable of providing clarity and insight into the topic, leaving the reader with an important message as it is in the authors’ aim is strongly recommended.
• At the same time, a separate paragraph titled ‘Limitations of the study’ explaining in what the study was limited and which the purposes to overcome them in the future is recommended too.

 

Minors

Line 83. To a level of scale

Line 163. The full stop was missed.

Figure 1 Caption is not clear. A full stop was probably missed.

Figure 2 Caption is not clear: ‘of the data set’

Dashed line. The correlation coefficient of the fitted power function to the data must be specified.

Figure 3. Caption: ‘of the’ instead of ‘on’.

Author Response

Reply to Reviewer 1

By the present study the authors present a multicriteria methodology to define small scale biorefineries. Data obtained from operational biorefineries are analyzed using a multivariate analysis combined with a hierarchical clustering.

To this aim, in the Methods section, the authors present well developed and described methodology consisting of four steps to generate the classification of biorefineries.

The method is then applied to a dataset obtained by 24 biorefinery projects leading to analyze data from 15 operational biorefineries.

However, the steps presented in the Methods are not specifically followed in the presentation of the Results, so that the reader is prevented to follow the developing of the applied methodology. Instead, the presentation of the Results is confusing and even more owing to they are presented in a single Results and Discussion section.

Finally, a quite short and generic paragraph of Conclusion ends the manuscript completely missing a perspective for future analysis as well as an analysis of the limitation of the study.

Based on these points, this reviewer rises the following criticisms:

First, how the authors can demonstrate that the number of biorefineries, 15, where they obtain the data, is consistent with a significative multivariate analysis? This point was never considered in the manuscript.

Response 1: Indeed, this point was never explicitly discussed; the revised version now includes a new section “4.1.3 Limitations of the work”. The manuscript did include two analysis related to the statistical consistency of the results (section 3.3.2 and 3.4), however we agree that this section was lacking.

Results and Discussion must be presented in separated sections. Then, the results must be presented specifically following the same steps shown in the Methods, so that the reader can easily follow the realization and the developing of the methodology.

Response 2: Indeed, we have reorganised the manuscript accordingly. In particular the results section now follows the methodological steps.  

Following the Discussion, a wider Conclusion capable of providing clarity and insight into the topic, leaving the reader with an important message as it is in the authors’ aim is strongly recommended.

Response 3: We have improved the conclusion along these guidelines.

At the same time, a separate paragraph titled ‘Limitations of the study’ explaining in what the study was limited and which the purposes to overcome them in the future is recommended too.

Response 4:  A new section “4.1.3 Limitations of the work” was added which contains a solution to overcome the main limitation, limited data availability.

Reviewer 2 Report

Minor comments

 

Introduction

Line 66…. “In this work, we make the hypothesis that the scale of a biorefinery can be outlined from studying/analyzing existing biorefineries”

• Consider replacing with “In this work, we state/test the hypothesis that the scale of a biorefinery can be outlined from studying/analyzing existing biorefineries

 

Lines 86 and 87…. “A classification of biorefineries is obtained through multivariate analysis combined with unsupervised clustering”

• The authors should provide further explanation of what they mean by unsupervised clustering

 

Lines 87 and 88…. “a stability analysis of the classification is carried out by running the clustering method after generating perturbations on the dataset”

• What do the authors mean by “..generating perturbations on the dataset”

 

Lines 173 and 174….. “A perturbation is simply the exclusion of a combination of actors from the dataset”

• Based on what rule/principle or on what grounds was this exclusion undertaken?

Author Response

Reply to Reviewer 2

Introduction

Line 66…. “In this work, we make the hypothesis that the scale of a biorefinery can be outlined from studying/analyzing existing biorefineries”

Consider replacing with “In this work, we state/test the hypothesis that the scale of a biorefinery can be outlined from studying/analyzing existing biorefineries

Response 1: Done. 

Lines 86 and 87…. “A classification of biorefineries is obtained through multivariate analysis combined with unsupervised clustering”

The authors should provide further explanation of what they mean by unsupervised clustering

Response 2 : Done. we added to the sentence “no pre-defined classes or properties are used as inputs”

Lines 87 and 88…. “a stability analysis of the classification is carried out by running the clustering method after generating perturbations on the dataset”

What do the authors mean by “..generating perturbations on the dataset”

Response 3: Done. this is explained further in section 2.4

Lines 173 and 174….. “A perturbation is simply the exclusion of a combination of actors from the dataset”

Based on what rule/principle or on what grounds was this exclusion undertaken?

Response 4:  We added the following sentence and add the reference 24  :

“ A common stability test consists in running clustering after removing one factor at a time and then in taking the average of the results [24]. Here the number of factors is not adequate to use this procedure; therefore we performed an adaptation by excluding a combination of factors from the dataset at a time, instead of only one“

Reviewer 3 Report

The purpose of the paper is to clarify the definition of the scale of a biorefinery. It is commonly known that large-scale biorefineries have adverse environmental effects, which cancel out the positive ones. However, this article does not discuss this balance between desirable vs undesirable outcomes of biorefineries, despite its importance, focusing on scale definition. However, the article does not show the need for formal classification of scale indisputably. I am unaware of cases of biorefineries that, being large-scale, with harmful effects, try to classify themselves as small-scale to hide these effects. As the financial support and public acceptance are defined case-by-case, the added value of the article is not outstanding. Additionally, the methodology is not innovative.

For all the mentioned reasons, I think the article would better suit a journal of engineering data compilation or as a support report to biorefinery funders. Therefore, my proposal is to reject it.

If the authors would like to use the study for other research papers in the future, my advice would be to develop on the less typical steps 3 and 4 of the methodology.

 

Author Response

Reply to Reviewer 3.

The purpose of the paper is to clarify the definition of the scale of a biorefinery. It is commonly known that large-scale biorefineries have adverse environmental effects, which cancel out the positive ones. However, this article does not discuss this balance between desirable vs undesirable outcomes of biorefineries, despite its importance, focusing on scale definition.

Response 1: According to the reviewer large-scale  biorefineries have undesirable effects on environment. That is fine but how does the reviewer define large-scale biorefinery ?

As scientists, we cannot do the investigation suggested by the reviewer without defining beforehand the scale of a biorefinery.

This just proves that the concept of scale presents a great interest for domain researchers because it encompasses several distinctive properties of a biorefinery. This paper contributes to clarify this. Moreover Scale definition is just one aspect of the work, the main result is certainly the multicriteria classification of biorefinery.    

However, the article does not show the need for formal classification of scale indisputably.

Response 2: To clarify this point we added the following text in the introduction section:

“Furthermore we want to use the concept of scale to distinguish classes of biorefinery with similar characteristics. This kind of classification is particularly useful in prospective analysis to assess and compare the sustainability performance of various type of biorefinery in a given context. It is also a way to address the complexity of these systems, to gain better understanding and to facilitate the communication with stakeholders and decision-makers”

And further in section “4.3 Future work”:

“The present classification is currently used as a typology in a scenario analysis with the aim to envision the sustainability performances of representative types of biorefineries in selected European regions. The biorefinery types reflect actual facilities and then are not defined arbitrarily. Note that building a typology of heterogeneous production systems as a first step of a sustainable assessment study is not uncommon; for example Díaz-Gaona et al., [37] recently developed a typology of organic livestock farms with this objective in mind and using the same kind of techniques as the one we used in this work.”

I am unaware of cases of biorefineries that, being large-scale, with harmful effects, try to classify themselves as small-scale to hide these effects.

Response 3: That would indeed be awkward, but how is this related to our manuscript ?

As the financial support and public acceptance are defined case-by-case, the added value of the article is not outstanding.

Response 4: We don’t understand this argument. The added value of the article is scientific (better understanding of biorefineries strategy) and the societal (envisioning alternative biorefinery solutions for regional development).

More precisely the manuscript will help to distinguish biorefinery types based on data about real operating facilities. This is particularly useful to select the realistic systems that will be used in a second time for scenario assessment to determine sustainability indicators, as mentioned in section 4.3. As a matter of fact we built this classification for this purpose. 

Additionally, the methodology is not innovative.

Response 5: Our methodology combined techniques usually used to build typology, it presents some specific adaptions, though.  However the novelty definitely comes from the topic (defining scale of biorefinery using a data-based approach) and from its application in the biorefinery field. To our knowledge this is a first time this research question is addressed this way.

For all the mentioned reasons, I think the article would better suit a journal of engineering data compilation or as a support report to biorefinery funders. Therefore, my proposal is to reject it.

Response 6 : We strongly disagree with this suggestion. As explained in 4.3 section, this work is a first step for sustainability assessment, that is why we chose this journal.

Moreover papers with similar approach have been published in this journal for example Díaz-Gaona et al., 2019, see reference [37] in the manuscript.

If the authors would like to use the study for other research papers in the future, my advice would be to develop on the less typical steps 3 and 4 of the methodology.

Thanks you for your suggestion.

Round 2

Reviewer 1 Report

Dear Editor, I am sorry for the delay but at the moment and for few days I am not in my office so I did not succeeded in returning you the form. Nevertheless I read the revised manuscript and the answers to my questions and I concluded that the manuscript is now suitable for the publication in your journal.

Reviewer 3 Report

Unfortunately I do not feel comfortable assessing the authors’ replies, which include questions and disagreements. Answering such an opposed view will not bring any added-value to the paper. Overall, the paper remains the same, so does my proposal.