Prosecution Insights
Last updated: April 19, 2026
Application No. 18/254,427

PROCESS FOR OPERATING AN ELECTROLYSIS APPARATUS AND ELECTROLYSIS APPARATUS

Final Rejection §103
Filed
May 25, 2023
Examiner
KEELING, ALEXANDER W
Art Unit
1795
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Siemens Energy Global GmbH & Co. Kg
OA Round
2 (Final)
56%
Grant Probability
Moderate
3-4
OA Rounds
3y 4m
To Grant
95%
With Interview

Examiner Intelligence

Grants 56% of resolved cases
56%
Career Allow Rate
320 granted / 570 resolved
-8.9% vs TC avg
Strong +39% interview lift
Without
With
+38.8%
Interview Lift
resolved cases with interview
Typical timeline
3y 4m
Avg Prosecution
56 currently pending
Career history
626
Total Applications
across all art units

Statute-Specific Performance

§101
0.8%
-39.2% vs TC avg
§103
53.2%
+13.2% vs TC avg
§102
19.1%
-20.9% vs TC avg
§112
20.1%
-19.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 570 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Response to Amendments This is a final office action in response to applicant's arguments and remarks filed on 02/25/2026. Status of Rejections The rejection of claim 9 is obviated by Applicant’s cancellation. All other previous rejections are maintained and updated in light of Applicant’s amendments. No new art is cited. New grounds of objection are necessitated by the Applicant’s amendments. Claims 8 and 10-15 are pending and under consideration for this Office Action. Drawings The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore, the limitation claiming “the cooling apparatus having an inclined orientation between an inflow side and an opposite and lower outflow side of the cooling apparatus” must be shown or the feature(s) canceled from the claim(s). However, Figure 1 shows the opposite orientation wherein the inflow side (represented by the arrow extending up from V2) is lower than the outflow side leading to 19 (“a recirculation conduit 19 at an open valve V3 the water stream W proceeds from the cooling apparatus 20 back to the electrolysis unit 3 in order, in its cooled state”, see page 6 of the instant specification). No new matter should be entered. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Claim Rejections - 35 USC § 103 The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. Claim(s) 8, 13, and 14 is/are rejected under 35 U.S.C. 103 as being unpatentable over Waidhas et al (US 20220380908 A1) in view of Nuntaphan et al (“Effect of inclination angle on free convection thermal performance of louver finned heat exchanger”, International Journal of Heat and Mass Transfer Volume 50, Issues 1–2, January 2007, Pages 361-366) and Takeuchi et al (US 20190024248 A1) Claim 8: Waidhas discloses a process for operating an electrolysis apparatus for splitting water (see e.g. abstract), the process comprising steps of: providing at least one electrolysis unit including at least one electrolysis cell (see e.g. #F2 on Fig 2), the at least one electrolysis unit having at least one inlet opening for a first reactant stream (see e.g. #12 on Fig 2) and at least one outlet opening for a first product stream (see e.g. #9 and #11 on Fig 2); producing the first product stream from the first reactant stream in the electrolysis unit (see e.g. [0037]: “The oxygen-water mixture formed during the electrolysis in the anode space 4 has a lower density than pure water” and “the hydrogen-water mixture ascends especially in the context of a “forced circulation” via a third conduit 11”); separating the product stream into a water stream and a gas stream (see e.g. #20 and #21 on Fig 2; [0037]: “In the first gas separation apparatus 20 the oxygen separates from the water” and “In the second gas separation apparatus 21 the hydrogen H2 separates from the water W”); cooling the water stream by introducing the water stream into at least one cooling apparatus dissipating heat of the water stream (see e.g. #6 on Fig 2; [0037]: “The water W is passed via a second conduit 15 into a first heat exchanger 6”). Waidhas does not explicitly teach that the heat of the water stream is dissipated directly to the environment. However, Waidhas does not have specific requirements for the heat exchanger (see e.g. [0037]: “The first heat exchanger 6 is operated with a coolant… The coolant inflow and outflow from the first heat exchanger 6 is not shown in FIG. 2 for the sake of simplicity”) and also teaches the benefits of heat exchanging with the environment (see e.g. [0011]). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to modify the method of Waidhas so that the heat of the water stream is dissipated directly to the environment because this type of heat exchange is taught in the reference. Waidhas does not explicitly teach that the cooling apparatus having an inclined orientation. As stated above, Waidhas does not have specific requirements for the heat exchanger. Nuntaphan discloses a study on the include of inclining heat exchangers, making it analogous art (see MPEP § 2141.01(a) I). Nuntaphan teaches that the inclination of certain heat exchangers can improve heat transfer performance (see e.g. abstract of Nuntaphan). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method Waidhas by having the cooling apparatus in an inclined orientation to improve heat transfer when that type of cooling apparatus is used for heat exchange. Waidhas in view of Nuntaphan does not explicitly teach that inclined orientation has the outflow side lower than the inflow side. However, there are only two possible orientations for the inclined heat exchanger: the outflow side higher than the inflow or the outflow side lower than the inflow. The instant specification states that it is preferred to have the outflow side lower than the inflow side to simply emptying the heat exchanger. However, the heat exchanger can be drained in either orientation so this feature is not considered critical. KSR rationale E states that it is obvious to choose “from a finite number of identified, predictable solutions, with a reasonable expectation of success”. Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to modify the method of Waidhas in view of Nuntaphan by selecting an orientation wherein the outflow side lower than the inflow side as a matter of design choice. Waidhas does not explicitly teach interrupting the cooling of the water stream upon a shutdown of the electrolysis unit or during a standby operation of the electrolysis unit; and detecting an ambient temperature during an offline state or the standby operation and upon the ambient temperature being below 1 °C, emptying the water stream from the cooling apparatus into a liquid storage device, the cooling apparatus being emptied due to a height difference between the cooling apparatus and the liquid storage device. Takeuchi teaches a water electrolysis system (see e.g. abstract), making it analogous art to the instant invention and Waidhas (see MPEP § 2141.01(a) I). Takeuchi teaches the following regarding the shutdown of the unit during freezing temperatures in [0005] and [0008]: In the above-described water electrolysis system, when operation of the water electrolysis device is stopped, the pressure of the hydrogen gas in the water electrolysis device is released, whereas the liquid water that was separated from the hydrogen gas remains present inside the gas-liquid separator. Therefore, in order to prevent the liquid water from freezing inside the gas-liquid separator in a cold climate or during winter or the like, when operation of the water electrolysis device is stopped…the liquid water inside the gas-liquid separator is capable of being drained into the drainage passage when operation of the water electrolysis device is stopped, freezing of the liquid water inside the gas-liquid separator can be suppressed with a simple configuration. The draining occurs due to a ”simple configuration” (see e.g. [0008]) of a height difference between the gas-liquid separator and the storage device (valves 62 and 64 are opened, allowing the water pulled down by gravity in the separator to flow out of the separator into the storage device, see e.g. #48 and #66 on Fig 1). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas by interrupting the cooling of the water stream upon a shutdown of the electrolysis unit or during a standby operation of the electrolysis unit and emptying the water stream from the cooling apparatus upon freezing conditions as taught in Takeuchi to prevent the water from freezing within the apparatus and causing damage. Furthermore, it would have been obvious to drain the water into the liquid storage device of Wainhas (see e.g. #30 on Fig 1) because Wainhas teaches that the water in the system is recycled (see e.g. [0037]). Furthermore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas so that the cooling apparatus is emptied due to a height difference between the cooling apparatus and the liquid storage device because Takeuchi teaches that this use of gravity flow is simple and suitable means of draining parts of the apparatus susceptible to freezing into the proper storage devices. Claim 13: Waidhas in view of Nuntaphan and Takeuchi the process further comprises providing a gas-water separator as the liquid storage device (see e.g. Waidhas - #20 and #21 on Fig 2), and using the gas-water separator to affect the separation of the water stream and the gas stream during operation (see e.g. Waidhas - [0037]). Claim 14: Waidhas in view of Nuntaphan and Takeuchi the process further comprises using an additional container as the liquid storage device (see e.g. Waidhas - #30 on Fig 1). Claim(s) 10-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Waidhas in view of Nuntaphan and Takeuchi as applied to claim 9 above, and in further view of Harano et al (US 20180202053 A1). Claim 10: Waidhas in view of Nuntaphan and Takeuchi does not explicitly teach that the process further comprises replacing the water in the emptied cooling apparatus by a gas. Harano teaches a means of preventing freezing damage in an electrolytic apparatus (see e.g. abstract and [0085]), making it analogous art (see MPEP § 2141.01(a) I). The parts of electrolytic apparatus holding liquid are purged with nitrogen gas during stoppage to prevent the liquid from freezing (see e.g. [0085]). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas to include the steps of replacing the water in parts with flowing water by a gas as taught in Harano to prevent the liquid from freezing in the cooling apparatus. Claim 11: Waidhas in view of Nuntaphan and Takeuchi does not explicitly teach that the process further comprises emptying the cooling apparatus by pressurizing with pressurized gas. Harano teaches a means of preventing freezing damage in an electrolytic apparatus (see e.g. abstract and [0085]), making it analogous art (see MPEP § 2141.01(a) I). The parts of electrolytic apparatus holding liquid are purged with nitrogen gas during stoppage to prevent the liquid from freezing (see e.g. [0085]). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas to include the steps of emptying parts with flowing water by pressurizing with pressurized gas as taught in Harano to prevent the liquid from freezing in the cooling apparatus. Claim 12: Waidhas in view of Nuntaphan and Takeuchi using a process gas as the pressurized gas (nitrogen gas purge, see e.g. Harano - [0085]). Claim(s) 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Waidhas in view of Nuntaphan, Takeuchi, and Daimon et al (US 20170342579 A1). Claim 15: Waidhas discloses an electrolysis apparatus for splitting water (see e.g. abstract), the electrolysis apparatus comprising: an electrolysis unit including at least one electrolysis cell (see e.g. #F2 on Fig 2), at least one inlet opening for a first reactant stream (see e.g. #12 on Fig 2) and at least one outlet opening for a first product stream (see e.g. #9 and #11 on Fig 2); at least one gas-water separator for separating the product stream into a water stream and a gas stream (see e.g. #20 and #21 on Fig 2; [0037]: “In the first gas separation apparatus 20 the oxygen separates from the water” and “In the second gas separation apparatus 21 the hydrogen H2 separates from the water W”); and a cooling apparatus for cooling the water stream (see e.g. #6 on Fig 2; [0037]: “The water W is passed via a second conduit 15 into a first heat exchanger 6”); Waidhas does not explicitly teach that the heat of the water stream is dissipated directly to the environment. However, Waidhas does not have specific requirements for the heat exchanger (see e.g. [0037]: “The first heat exchanger 6 is operated with a coolant… The coolant inflow and outflow from the first heat exchanger 6 is not shown in FIG. 2 for the sake of simplicity”) and also teaches the benefits of heat exchanging with the environment (see e.g. [0011]). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to modify the method of Waidhas so that the heat of the water stream is dissipated directly to the environment because this type of heat exchange is taught in the reference. Waidhas does not explicitly teach that the cooling apparatus having an inclined orientation. As stated above, Waidhas does not have specific requirements for the heat exchanger. Nuntaphan discloses a study on the include of inclining heat exchangers, making it analogous art (see MPEP § 2141.01(a) I). Nuntaphan teaches that the inclination of certain heat exchangers can improve heat transfer performance (see e.g. abstract of Nuntaphan). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method Waidhas by having the cooling apparatus in an inclined orientation to improve heat transfer when that type of cooling apparatus is used for heat exchange. Waidhas in view of Nuntaphan does not explicitly teach said cooling apparatus being disposed in an inclined orientation between an inflow side and an opposite and lower outflow side of said cooling apparatus. However, there are only two possible orientations for the inclined heat exchanger: the outflow side higher than the inflow or the outflow side lower than the inflow. The instant specification states that it is preferred to have the outflow side lower than the inflow side to simply emptying the heat exchanger. However, the heat exchanger can be drained in either orientation so this feature is not considered critical. KSR rationale E states that it is obvious to choose “from a finite number of identified, predictable solutions, with a reasonable expectation of success”. Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date to modify the apparatus of Waidhas in view of Nuntaphan by selecting an orientation wherein the outflow side lower than the inflow side as a matter of design choice. Waidhas does not explicitly teach a control unit configured for interrupting the cooling of the water stream upon a shutdown of said electrolysis unit or during a standby operation of said electrolysis unit and that said control unit configured for emptying the water stream from said cooling apparatus into liquid storage upon the ambient temperature being below 1 C, said cooling apparatus being emptied due to a height difference between said cooling apparatus and said liquid storage. Takeuchi teaches a water electrolysis system (see e.g. abstract), making it analogous art to the instant invention and Waidhas (see MPEP § 2141.01(a) I). Takeuchi teaches the following regarding the shutdown of the unit during freezing temperatures in [0005] and [0008]: In the above-described water electrolysis system, when operation of the water electrolysis device is stopped, the pressure of the hydrogen gas in the water electrolysis device is released, whereas the liquid water that was separated from the hydrogen gas remains present inside the gas-liquid separator. Therefore, in order to prevent the liquid water from freezing inside the gas-liquid separator in a cold climate or during winter or the like, when operation of the water electrolysis device is stopped…the liquid water inside the gas-liquid separator is capable of being drained into the drainage passage when operation of the water electrolysis device is stopped, freezing of the liquid water inside the gas-liquid separator can be suppressed with a simple configuration. The draining occurs due to a ”simple configuration” (see e.g. [0008]) of a height difference between the gas-liquid separator and the storage device (valves 62 and 64 are opened, allowing the water pulled down by gravity in the separator to flow out of the separator into the storage device, see e.g. #48 and #66 on Fig 1). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas by interrupting the cooling of the water stream upon a shutdown of the electrolysis unit or during a standby operation of the electrolysis unit and emptying the water stream from the cooling apparatus upon freezing conditions as taught in Takeuchi to prevent the water from freezing within the apparatus and causing damage. Furthermore, it would have been obvious to drain the water into the liquid storage device of Wainhas (see e.g. #30 on Fig 1) because Wainhas teaches that the water in the system is recycled (see e.g. [0037]). Furthermore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the apparatus of Waidhas so that the cooling apparatus is emptied due to a height difference between the cooling apparatus and the liquid storage device because Takeuchi teaches that this use of gravity flow is simple and suitable means of draining parts of the apparatus susceptible to freezing into the proper storage devices. Waidhas in view of Takeuchi does not explicitly teach a temperature measuring apparatus for detecting an ambient temperature during an offline state or the standby operation. As discussed above, water freezing in the apparatus should be avoided. Daimon teaches an electrolysis cell for splitting water, making it analogous art to the instant invention and Waidhas (see MPEP § 2141.01(a) I). Daimon teaches including a temperature sensor “that detects a temperature environment in the housing, and preferably performs the freezing occurrence assessment step based on a detected temperature by the temperature sensor” (see e.g. [0054]). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the device of Waidhas in view of Takeuchi to include the temperature sensor of Daimon to detect dangerous freezing temperatures in the cell. Response to Arguments Applicant's arguments filed 02/25/2026 have been fully considered but they are not persuasive. On page(s) 7, the Applicant argues that Waidhaus does not disclose water being emptied from device 6 into device 30. This is not considered persuasive. The rejection never argued that Waidhaus taught this. The rejection stated “it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant invention to modify the method of Waidhas by interrupting the cooling of the water stream upon a shutdown of the electrolysis unit or during a standby operation of the electrolysis unit and emptying the water stream from the cooling apparatus upon freezing conditions as taught in Takeuchi to prevent the water from freezing within the apparatus and causing damage. Furthermore, it would have been obvious to drain the water into the liquid storage device of Wainhas (see e.g. #30 on Fig 1) because Wainhas teaches that the water in the system is recycled (see e.g. [0037]). On page(s) 7-8, the Applicant argues that Takeuchi does not disclose emptying the water into a liquid storage device and only discloses draining the water. This is not considered persuasive. [0050] states “The first water drainage passage 60 is a passage for guiding the liquid water inside the gas-liquid separator 48 to the water sealing unit 66”. On page(s) 8-9, the Applicant argues that the prior art does not disclose nor render obvious the new amendments added to claims 8 and 15. This is not considered persuasive. These limitations were shown to be obvious over the prior art in the updated art rejection above. Conclusion THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to ALEXANDER W KEELING whose telephone number is (571)272-9961. The examiner can normally be reached 7:30 AM - 4:00 PM. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Luan Van can be reached at 571-272-8521. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /ALEXANDER W KEELING/Primary Examiner, Art Unit 1795
Read full office action

Prosecution Timeline

May 25, 2023
Application Filed
Feb 05, 2026
Non-Final Rejection — §103
Feb 25, 2026
Response Filed
Mar 28, 2026
Final Rejection — §103 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12577689
CATHODE ELECTRODE, COMPOSITE OF CATHODE ELECTRODE AND SUBSTRATE, AND METHOD OF MANUFACTURING COMPOSITE OF CATHODE ELECTRODE AND SUBSTRATE
2y 5m to grant Granted Mar 17, 2026
Patent 12577694
ALTERNATING CURRENT ELECTROLYSIS SYSTEM, AND METHOD AND DEVICE FOR CONTROLLING THE SAME
2y 5m to grant Granted Mar 17, 2026
Patent 12571117
OPERATION SUPPORT METHOD, OPERATION SUPPORT DEVICE, OPERATION SUPPORT SYSTEM, AND OPERATION SUPPORT PROGRAM
2y 5m to grant Granted Mar 10, 2026
Patent 12559849
WATER SPLITTING CATALYST
2y 5m to grant Granted Feb 24, 2026
Patent 12534812
CATHODIC PROTECTION OF CONCRETE USING AN ANODE ATTACHED TO AN OUTER SURFACE.
2y 5m to grant Granted Jan 27, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

3-4
Expected OA Rounds
56%
Grant Probability
95%
With Interview (+38.8%)
3y 4m
Median Time to Grant
Moderate
PTA Risk
Based on 570 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month