Overcoming the Challenges for a Mass Manufacturing Machine for the Assembly of PEMFC Stacks

Round 1

Reviewer 1 Report

This manuscript demonstrates the effect of a mass manufacturing machine on the reduction of the PEMFC (polymer electrolyte membrane fuel cell) assembly costs. This would be effective at evaluating the significance of the automatically mass manufacturing to reduce PEMFC system costs. However, the manuscript should be revised according to the following comments.

(1) Figure 1 indicates that more than 80 % of the material and manufacturing costs are caused by four components: the bipolar plates (BPPs), the membranes, the catalyst layers and the gas diffusion layers (GDLs) at a production rate of 1,000 PEMFC stacks. However, if the production rate is increased to 500,000, 70 % of the stack costs will be caused by two components: the BPPs and the catalyst layers. The authors had better explain the reason why the contribution of the PEMFC component costs is significantly varied depending on the production rate.

(2) The PEMFC system are consisted of stack components, such as the membrane, the catalyst layer, the gas diffusion layer and the bipolar plate, and ancillary units, such as the thermal management, water management, air and fuel supply systems. The authors had better describe the cost reductions in these components and systems due to the developed mass production.

Author Response

Dear expert,

Thank you very much for your comments, by which we could improve our article accordingly.

(1) Regarding your first comment:

From the issue you mentioned, we assume that you mean Figure 2-4 and not Figure 1. We have tried to further explain the issue you mentioned (“reason why the contribution of PEMFC component costs varies greatly depending on the production rate”).

The following addition/explanation has been added in line range 111-117:

“The contribution of the PEMFC component costs varies greatly depending on the production rate because the manufacturing costs consist of the material costs and the costs for the processing steps. While the latter can be significantly reduced with the quantity produced (such as GDL), above all due to adapted production methods, the material costs, especially of noble metals (such as catalyst formulation, Pt etc.), are largely independent of economies of scale. These are mainly dependent on the respective raw material prices, which are also subject to fluctuations over time, but which are far more difficult to calculate and moreover tend to increase with increased demand.”

(2) Regarding your second comment:

We have tried to further explain the issue you raised (“cost savings due to the mass manufacturing machine developed for components and systems”).

The following addition/explanation has been added in line range 144-151:

“Nevertheless the costs for the more highly processed components of the stack (as well as most parts of the BOP, compressors, pumps, sensors etc.) are naturally subject to a certain economies of scale. This alone reduces procurement costs with increasing purchase volumes. Furthermore, the automated process steps of the mass production plant described in this article result in significant savings in production time and personnel requirements for the production of fuel cell stacks. In addition, completely new component concepts can be used from the transition from a manual stacking process to an automated process, which were not easy to implement before. Both factors are decisive for a further reduction in manufacturing costs”

Please see also the other changes in the paper. Many thanks in advance for your support!

Reviewer 2 Report

The manuscript describes the design process for a machine suitable for mass manufacturing of fuel cell stacks.
As an introduction the distribution of costs for several fuel cell systems is summarized, which gives a good motivation for the subject. In the following part the design process of the production line is presented.
A major shortcoming is the lack of suitable references. Of course, the authors explain that there is very little literature in the field of fuel cell mass production. On the other hand: the manuscript exhibits a total of 14 references, out of which seems to be one scientific paper, 3 videos on youtube and the remaining are reports or presentations. Furthermore, these references (besides the videos) support the cost calculation presented in the introduction. There are no appropriate references for the main subject of the assembly line. It is suggested that the authors should add the respective literature which is available, e.g. for the topic of "configurable assembly systems".
The formatting of the existing references should be checked - there is information missing as given at the end of this text.

Minor issues:
#1 Address
The address is missing in line 4-7. (E.g., which Fraunhofer Institute, City, Country?)

#2 missing reference in line 71
There seems to be an unfinished citation "[sources]"

#3 missing reference in line 137
Where can the information about these projects be retrieved from?

#4 Figure 2, Figure 3 and Figure 5
The figure has very low contrast/ is of low quality. Should be improved.

#5 Figure 8
What about the copyright? The figure comes from a German magazine (from reference [13]).

#6 Figures 11 and 12
These figures contain both a table and a figure. The table should be separated as table,
thus the figure becomes larger and is easier to read.

#7 References
2. Wannemacher, T. (Proton Motor Fuel Cell GmbH): FCREEV -Fuel Cell Range Extended Vehicle (HyRange
25 Projekt MAGNA FCREEV), -e-Monday, presentation, September 2017; pp. 12– 22.
-> where to get it?

3. Porstmann, S.; Scheffler, S. (Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik IWU):
Analysis on the supportive technology for optimized manufacturability vs. stack performance. Deliverable
No. Fit-4-AMandA D1.2 2018-02-26; Horizon 2020 | FCH-01-1-2016 | Manufacturing technologies for
PEMFC stack components and stacks GA # 735606.
-> where to get it?
-> what is it (report/ paper/poster)?
-> third author missing

4. James, B. D.; Huya-Kouadio, J. M.; Houchins, C. (Strategic Analysis Inc.): Bipolar Plate Cost and Issues at
High Production Rate ( DOE Workshop on Research and Development Needs for Bipolar Plates for PEM
Fuel Cell Technologies), Southfield - Michigan, February 2017.
-> what is it (presentation/ paper/ poster)?
-> where to get it?

8. James, B. D. et al (Strategic Analysis Inc.): Mass Production Cost Estimation of Direct H2 PEM Fuel Cell
Systems for Transportation Applications: 2017 Update, December 2017.
- co-authors missing
-> what is it (presentation/ paper/ poster)?
-> where to get it?

9. Wilson, A.; Kleen, G.; Papageorgopoulos, D. (DOE Hydrogen and Fuel Cells Program Record): Fuel Cell
System Cost – 2017, September 2017.
-> what is it (presentation/ paper/ poster)?
-> where to get it?

10. Thompson et al: Direct hydrogen fuel cell electric vehicle cost analysis: System and high-volume
manufacturing description, validation, and outlook, ELSEVIER, September 2018.
-> what is it (presentation/ paper/ book)?
-> where to get it?

11. James, B. D., (Strategic Analysis Inc.), (U.S. DEPARTMENT OF ENERGY, OFFICE OF ENERGY
EFFICIENCY & RENEWABLE ENERGY): 2018 Cost Projections of PEM Fuel Cell Systems for Automobiles
and Medium-Duty Vehicles, April 2018.
-> what is it (presentation/ paper/ poster)?
-> where to get it?

12. Kraft, J. (Elring Klinger): PEMFC Technology; Stack manufacturing processes and quality techniques;
PEMFC stack and MEA manufacturing workshop, October 2018, Brussels.
-> what is it (presentation/ paper/ poster)?
-> where to get it?

13. Richter, T. (Aumann Limbach-Oberfrohna GmbH): Aiming for scalability and efficiency, automated
production and assembly of fuel cells, Autoland Saxony, 2018; pp. 18–19.
-> what is it (presentation/ paper/ poster)?
-> where to get it?

14. Wittstock, R.; Pehlken, P.; Wark, M.: Challenges in Automotive Fuel Cells Recycling. Article in MDPI
Journal recycling, December 2016.
-> which issue, page numbers, DOI?

Author Response

Dear expert,

Thank you very much for your comments, by which we could improve our article accordingly.

Regarding your first comment (“It is suggested that the authors should add the respective literature which is available, e.g. for the topic of "configurable assembly systems").

The following addition/explanation has been added in line range 166-172:

The scarcity of references on the subject of mass production is assumed to be that this is not the current focus of academic activity. The subject of mass manufacturing is however the daily business of machine and plant manufacturers and their customers who want to manufacture products in high volumes (e.g. Tier suppliers). Typically standardized components and assemblies (drives, assembly lines, robots, etc.) are used. There are several publications on the topic of automated assembly lines, e.g. [20], [21], [22] from which general approaches to methodology can be derived. However, the specific developments are mostly confidential and unpublished.

ToDo2:           The formatting of the existing references should be checked - there is information missing as given at the end of this text.

Regarding your second comment, the following chance has been done:

#1 Address
The address is missing in line 4-7. (E.g., which Fraunhofer Institute, City, Country?)

*Addition of the data for all authors.

#2 missing reference in line 71
There seems to be an unfinished citation "[sources]"

*The sources are listed in the following sentence.

#3 missing reference in line 137 (now line range 155-158)
Where can the information about these projects be retrieved from?

*Addition of the sources to the listed projects (in the text line section 155-158; in the source list)

#4 Figure 2, Figure 3 and Figure 5
The figure has very low contrast/ is of low quality. Should be improved.

*The figures were reworked accordingly.

#5 Figure 8
What about the copyright? The figure comes from a German magazine (from reference [13]).

*This figure was created within the framework of the EU project Fit-4-AMandA (Funding programme H2020-JTI-FCH-2016-1 | Manufacturing technologies for PEMFC stack components and stacks, GA No 735606). The image rights (copyright) are therefore held by the consortium and not by the publisher.

#6 Figures 11 and 12
These figures contain both a table and a figure. The table should be separated as table,
thus the figure becomes larger and is easier to read.

*The figures were reworked/separated accordingly.

#7 References

*All references (line range 610-716) have been reworked or completed according to your suggestions.

Please see also the other changes in the paper. Thank you very much for your support.

Round 2

Reviewer 1 Report

This manuscript demonstrates the effect of a mass manufacturing machine on the reduction of the PEMFC (polymer electrolyte membrane fuel cell) assembly costs. This would be effective at evaluating the significance of the automatically mass manufacturing to reduce PEMFC system costs. Therefore, the reviewer recommends that the manuscript be accepted for publication in Machines.