Round 1

Reviewer 1 Report

This is a complete study, and all the data and analysis are correct and reasonable. However, there is a little English grammatical error in the article.

Author Response

 This is a complete study, and all the data and analysis are correct and reasonable. However, there is a little English grammatical error in the article.

Response: Thank you for your comments. We have carefully corrected the English language of the manuscript.

Reviewer 2 Report

The literature review lacks information on other forms of use of biomass to generate energy from them. And changes in the cost-effectiveness of biomass compared to other energy sources. e.g. publications.  

DOI:10.1007/s00226-021-01350-1

DOI:10.35812/CelluloseChemTechnol.2021.55.52

DOI:10.5604/01.3001.0014.4414

DOI:10.5604/01.3001.0015.3633

DOI:10.15376/biores.16.3.5618-5627

DOI:10.3390/en14082132

DOI:10.15376/biores.13.4.8629-8645

DOI:10.5604/01.3001.0015.2373

  

The conclusions presented are a discussion of the results. 

A conclusion could be e.g.: Mixing low-energy components with high-energy components in a ratio of 123 produces a fuel with higher energy content. 
The use of blends of high energy fuels with low energy fuels increases the available raw material base.
 And similar expressions. 

Author Response

Point 1: The literature review lacks information on other forms of use of biomass to generate energy from them. And changes in the cost-effectiveness of biomass compared to other energy sources. e.g. publications.

 

Response 1: We choose to define our scope of work, for the utilization of biomass for the production of charcoal briquettes only.

 

Point 2: The conclusions presented are a discussion of the results. 

                A conclusion could be e.g.: Mixing low-energy components with high-energy components in a ratio of 123 produces a fuel with higher energy content. 

                The use of blends of high energy fuels with low energy fuels increases the available raw material base.

                And similar expressions

               

Response 2: Thank you, we have agreed with your suggestion and have revised the conclusion part.: The results of the mixing design experimental method, mixing 3 types of charcoal powder per formulation. Allows to increase the quality and value of biomass charcoal powder (raw material) that has a low heating value, but is sufficiently available throughout the year, the mixing of secondary ingredient with raw materials having a high heating value (main ingredient), the charcoal briquette production must be qualified and meet the industrial product standards and approved for the commercial.

Reviewer 3 Report

Using the simplex-centroid experimental method, the author(s) investigated the starting charcoal ratio and the charcoal ratio to be blended or formulated to produce charcoal briquettes from the mixture of eucalyptus bark coal (EuBC), rice husk coal (RHC), and charcoal from a biomass power plant (CBPP). This was done to increase the quality and value of raw material that has a low heating value. The three chosen raw materials are very unique and of high interest. The authors have excellent knowledge of the topic. This is an interesting work that will be useful for biogas producers.

However, some revisions are necessary before recommending the article for publication.

(1) To produce the biomass charcoal briquettes, it will be interesting if the authors can clearly state the reason or motivation behind selecting these three (3) biomasses materials: eucalyptus bark coal (EuBC), rice husk coal (RHC), and charcoal from a biomass power plant (CBPP).

(2) On page 2, lines 92-93, the authors wrote, and I quote “The charcoal powder and binder are mixed before being compressed into charcoal briquettes by a charcoal briquette machine using the principle of cold compression.”

Also on page 5, line 84-85, the author(s) wrote, and I quote “The condition of mixture formula and proportion of charcoal powder in this experiment were such that each mixture contained 3 types of charcoal powder with no binder in the mixture, as shown in Table 3.”

From these 2 statements, I do not know if a binder is used or not. Please can you clarify this? Did you use a binder or not? If a binder is used, can you state specifically the type of binders used, and the reason for using such binder?

(3) Mechanical durability of biomass is a determinant factor as far as the strength and combustion ability of the biomass are concerned. It will be much appreciated if the author(s) can evaluate the mechanical durability of the charcoal briquettes from the mixture of eucalyptus bark coal (EuBC), rice husk coal (RHC), and charcoal from a biomass power plant (CBPP).

(4) The present findings encouraged the use of eucalyptus bark coal (EuBC), rice husk coal (RHC), and charcoal from a biomass power plant (CBPP) for bioenergy purposes and briquette production. To explore other wastes as possible candidates for bioenergy applications, the authors can consider the following recent papers on biomass for combustion and bioenergy production; they can be of use in the background study on biomass, in the revised manuscript.

(a) Olugbade, T.O., Ojo O.T. (2020) Binderless briquetting technology for lignite briquettes: a review. Energy Ecol Environ. 6:69-79.

(b) Olugbade T, Ojo O, Mohammed T (2019) Influence of binders on combustion properties of biomass briquettes: a recent review. Bioenergy Research 12:241–259.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The literature review lacks information on other forms of biomass utilisation for energy purposes such as: biogas, bioethanol, furan fuels. Some information is available in the literature:  

https://doi.org/10.3390/en14102968

https://doi.org/10.35812/CelluloseChemTechnol.2021.55.52 https://doi.org/10.1007/s00226-021-01350-1 https://doi.org/10.3390/en14082132  

 

The wording used in the proposals needs to be improved. These elements are results of the authors' work not conclusions.  

Charcoal A (eucalyptus bark charcoal, EuBC) had the average HHV of 3,779.98 cal/g, charcoal B (rice husk coal, RHC) had the average HHV of 4,863.29 cal/g, whereas charcoal 
C (charcoal from a biomass power plant, CBPP) had the average HHV of 5,991.18 cal/g. 
According to the Mixture Design of Simplex-Centroid experiment, it was found that the mixture proportion of charcoal A = 50%, charcoal B = 37.4% and charcoal C = 12.6% produced the HHV of 4,500 cal/g which followed the product standards of Bionic Charcoal 
Briquettes (TCPS No.946/2005), while the mixture proportion of charcoal A = 29.21%, charcoal B = 0.98% and charcoal C = 69.82% produced the HHV of 5,500 cal/g which followed the product standards of Charcoal Briquettes (TCPS No.238/2004). 
The results of evaluation and validation of the prediction model found that the Average Absolute Error (AAE) was 0.08 or 7.7% and the Average Bias Error (ABE) was 0.07 or 7.2%

The following formulations can be adopted as a conclusion after reconstruction. 

Conclusions should be short statements that take a general form and are true.
Example.
Adding a low-energy raw material to pellets produces more ash.
By adding low-energy raw material to the pellets, it is possible to produce pellets for the whole heating period.
By the addition of low-energy raw materials to pellets significantly does not affect the cooking time of food / decrease in efficiency of heating boilers ...

 

Please refer to this standard on the use of units of measurement and application (it is about commas before units).  

ISO 80000- 1:2013-07

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

All corrections have been made. 

Author Response

Thank you for your comments.