Economic Modelling of Mixing Hydrogen with Natural Gas
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors give an Economic calculation for H2 blending with natural gas. The topic of H2 mixing with existing natural gas pipelines is a feasible way to transport H2 to end users. Therefore, economic performance will be important to the operators. Through modeling, an online calculator is provided and compared with different parameters. Overall, the paper needs major revision before it can be considered for publication. Detail questions and comments:
1. Parameter studies need to be carried out, like the changing of natural gas prices and H2 prices. For example, 5 euro/m3 H2 seems a very high price, double check this price and unit, 5 Euro/kg H2 seems reasonable.
2. In Fig.3, sub-figures should be annotated as (a) (b). For the Cost of Volum m3 and EUR in the figures, what's the baseline? m3/h and EUR/h?
3. How about the price of CO2 tax? Did you consider this price? If the CO2 tax is not considered, economic performance is no possible to be good.
4. It's suggest to add one or two figures study the change of price of natural gas and H2.
Comments on the Quality of English Language
The English is acceptable and a gramma edit is needed.
Author Response
We would like to thank the reviewer for the valuable comments. We have updated our article based on the suggestions and provided our response in the attached word file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
1. This paper presents an economic analysis of blended hydrogen/natural gas mix. The paper provides useful information and has practical significance.
2. The paper is generally written well. Some clarifications, though, need to be made, as mentioned below.
3. Assumptions of the analyses should be clearly stated. For example, the assumption for Figures 5 and 6 should be that the blended gas volume is fixed. Figures 5 and 6 are basically the same; it is suggested to use the same color for CO2 and Heat Value. For Figure 7, please clarify that the cost is based on a unit heat value produced.
4. It is suggested to add a discussion on the optimal amount of H2 based on the benefit/cost analysis, which will help the reader make decisions.
Author Response
We would like to thank the reviewer for the valuable comments. We have updated our article based on the suggestions and provided our response in the attached word file.
Author Response File: Author Response.pdf
