Prosecution Insights
Last updated: April 19, 2026
Application No. 18/923,347

Methods of Modifying Existing Gas Turbine Engine Design to Create a Combined Storage Engine and Simple Cycle Peaker Product

Final Rejection §102§103§112§DP
Filed
Oct 22, 2024
Examiner
DOUNIS, LAERT
Art Unit
3746
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Powerphase International LLC
OA Round
2 (Final)
68%
Grant Probability
Favorable
3-4
OA Rounds
2y 5m
To Grant
89%
With Interview

Examiner Intelligence

Grants 68% — above average
68%
Career Allow Rate
562 granted / 831 resolved
-2.4% vs TC avg
Strong +21% interview lift
Without
With
+21.3%
Interview Lift
resolved cases with interview
Typical timeline
2y 5m
Avg Prosecution
23 currently pending
Career history
854
Total Applications
across all art units

Statute-Specific Performance

§101
1.0%
-39.0% vs TC avg
§103
41.5%
+1.5% vs TC avg
§102
21.1%
-18.9% vs TC avg
§112
29.2%
-10.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 831 resolved cases

Office Action

§102 §103 §112 §DP
DETAILED ACTION The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Application Status This office action is in response to amendments/arguments filed on December 15, 2025. Applicant has amended Claims 1, 5, and 7, and cancelled Claims 6 and 8. Claims 1 – 5 7, and 9 are currently pending. Response to Arguments Applicant’s arguments have been fully considered. Previous double patenting rejections are withdrawn due to submission and approval of a terminal disclaimer. With regards to previous prior art rejections, applicant argues that the features of Claim 8, previously objected to as being allowable, were incorporated into the independent claims. Examiner respectfully disagrees. Claim 8 previously required replacing at least one airfoil of a stator of the compressor with a strut. Claims 1 and 5 now recite removing at least one airfoil of a stator of the compressor. These are not the same features. In fact, Nakhamkin was/is relied on to teach complete removal of stator airfoils. Previous prior art rejections stand. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(d): (d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph: Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. Claim 7 is rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends. Claim 7 recites further comprising removing at least one airfoil of a stator of the compressor. This exact step is already present in Claim 5, upon which claim 7 exists. Thus, Claim 7 is not further limiting. Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements. Claim Rejections - 35 USC § 102 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale or otherwise available to the public before the effective filing date of the claimed invention. (a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention. Claims 1 – 4 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Nakhamkin (US 4872307). With regards to Claim 1: Nakhamkin (Figure 1) discloses a method of modifying an existing gas turbine to create a storage engine (Col. 2, Lines 56+: “retrofit of existing simple cycle gas turbine engines (SCGTs) to provide peaking energy for CAES application”), the gas turbine having a combustor (combustor 120), a compressor section (compressor 140), and a turbine section (turbine 115), the method comprising: modifying the compressor section of the gas turbine to form the storage engine (Col. 5, Lines 1+: “In accordance with the invention, compressor 140 is initially debladed since such compressor is not to be utilized for the compression of air”) such that air supplied to the combustor of the storage engine is heated by exhaust of the storage engine (Col. 5, Lines 18+: “compressed air from air storage device 200 is pretreated in a recuperator (not shown) before the air is provided to combustor 120. Exhaust gas from turbine 100 is supplied to the recuperator as its source of heat”) and is supplied from a remote source of air (underground storage 200, compressors 40, 60), wherein modifying the compressor section includes removing a rotatable airfoil of a compressor and removing at least one airfoil of a stator of the compressor (Col. 5, Lines 1+: “In accordance with the invention, compressor 140 is initially debladed since such compressor is not to be utilized for the compression of air”, given that the compressor “is not to be utilized for the compression of air”, one of ordinary skill in the art would interpret “deblading” as removing all rotating blades and stator blades from the compressor). With regards to Claim 2: Nakhamkin discloses the remote source of air is a compressed air storage tank (underground storage 200). With regards to Claim 3: Nakhamkin discloses the remote source of air is a combination of a compressed air storage tank (underground storage 200) and a plurality of low-pressure compressors (compressors 40, 60). With regards to Claim 4: Nakhamkin discloses the remote source of air includes a plurality of low pressure compressors (compressors 40, 60). Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claims 5 and 7 are rejected under 35 U.S.C. 103 as being unpatentable over Nakhamkin (US 4872307) in view of Larson et al. (hereafter “Larson” – US 2019/0063222). With regards to Claim 5: Nakhamkin (Figure 1) discloses a method of modifying an existing gas turbine having a combustor (combustor 120), a compressor section (compressor 140), and a turbine section (turbine 115), the method comprising: modifying the compressor section of the existing gas turbine to form a storage engine (Col. 2, Lines 56+ of Nakhamkin: “retrofit of existing simple cycle gas turbine engines (SCGTs) to provide peaking energy for CAES application”) by: removing at least one of a plurality of rotatable airfoils of a compressor of the compressor section (Col. 5, Lines 1+: “In accordance with the invention, compressor 140 is initially debladed since such compressor is not to be utilized for the compression of air”); removing at least one airfoil of a stator of the compressor (Col. 5, Lines 1+: “In accordance with the invention, compressor 140 is initially debladed since such compressor is not to be utilized for the compression of air”, given that the compressor “is not to be utilized for the compression of air”, one of ordinary skill in the art would interpret “deblading” as removing all rotating blades and stator blades from the compressor). Nakhamkin does not disclose introducing a thrust piston on a shaft line. Larson (Figure 1) teaches a gas turbine (1) including a thrust piston (10) on a shaft line (2). Larson teaches that “to maintain good control over the axial thrust and its direction … gas turbines sometimes have an axial thrust piston upon which acts compressor air and on account of the force direction predetermined by the compressor air can act upon the rotor with an axial compensating force” (Paragraph 4), thereby allowing for adjustment of an axial compensation thrust (Paragraph 8). MPEP 2143A teaches it is obvious to combine prior art elements according to known methods in order to yield predictable results. In this case, the addition of thrust pistons is known in the art and it would have been obvious to one of ordinary skill to modify Nakhamkin by adding a thrust piston the shaft in order to yield the predictable benefits described above. With regards to Claim 7: The Nakhamkin modification of Claim 5 teaches removing at least one airfoil of a stator of the compressor (Col. 5, Lines 1+ of Nakhamkin: “In accordance with the invention, compressor 140 is initially debladed since such compressor is not to be utilized for the compression of air”, given that the compressor “is not to be utilized for the compression of air”, one of ordinary skill in the art would interpret “deblading” as removing all rotating blades and stator blades from the compressor. Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Nakhamkin (US 4872307) in view of Larson et al. (hereafter “Larson” – US 2019/0063222), further in view of Kraft et al. (hereafter “Kraft” – US 2015/0233296). With regards to Claim 9: The Nakhamkin modification of Claim 5 does not explicitly teach associating an auxiliary fueled engine with the gas turbine. Kraft (Figures 4 and 10) teaches a gas turbine system comprising a compressor (10) combustor (14), and turbine (16), as well as a fueled engine driven compressor (compressor 116, driven by fueled engine 151). Kraft teaches that “using a supplemental compressor driven by a fueled engine,… [allows for] operation … which is independent of the electric grid” (Paragraph 47). Given the teachings of Kraft, it would have been obvious to one of ordinary skill in the art to modify the system of Nakhamkin by associating the gas turbine with an auxiliary fueled engine, as taught by Kraft, to yield the predictable benefits of independence from the electric grid, thereby improving operational availability. Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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. Inquiries Any inquiry concerning this communication or earlier communications from the examiner should be directed to LAERT DOUNIS whose telephone number is (571)272-2146. The examiner can normally be reached on Mon. - Thurs: 10a - 4:30p. 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, MARK LAURENZI can be reached on (571) 270-7878. 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. /Laert Dounis/ Primary Examiner, Art Unit 3746 Saturday, January 17, 2026
Read full office action

Prosecution Timeline

Oct 22, 2024
Application Filed
Sep 11, 2025
Non-Final Rejection — §102, §103, §112
Dec 15, 2025
Response Filed
Jan 17, 2026
Final Rejection — §102, §103, §112 (current)

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Prosecution Projections

3-4
Expected OA Rounds
68%
Grant Probability
89%
With Interview (+21.3%)
2y 5m
Median Time to Grant
Moderate
PTA Risk
Based on 831 resolved cases by this examiner. Grant probability derived from career allow rate.

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