In Ex Parte Nakhamkin, the Board reversed the examiner’s obviousness rejection as relying solely on a per se rule of obviousness. Ex Parte Nakhamkin, No. 2012-003291 (B.P.A.I. May 23, 2012). The Board emphasized that “when determining whether a claim is obvious, an Examiner must make ‘a searching comparison of the claimed invention – including all its limitations – with the teaching of the prior art.’” Id. at 5 (citing In re Ochiai, 71 F.3d 1565, 1572 (Fed. Cir. 1995)).

The invention on appeal was directed to an adiabatic compressed air energy storage (CAES) system and a method of utilizing and recovering energy and heat obtained during low pressure compression of air with an adiabatic CAES system. Independent claim 1, which is illustrative of the subject matter, recites:

An adiabatic Compressed Air Energy Storage (CAES) system, comprising:

[i] a low pressure compressor structure … [ii] a first heat exchanger … [iii] a thermal storage device … [iv] a motor-driven high pressure compressor … [v] an aftercooler … [vi] an air storage … [vii] a second heat exchanger … and [viii] a turbine structure constructed and arranged to expand the preheated compressed air released from the air storage to produce power,

wherein the preheated compressed air expanded by the turbine structure is heated only by heat from the thermal storage device and without burning fuel. Id. at 2–3 (emphasis in original) (brackets added).

Rejecting claim 1 as obvious, the Examiner found that Frutschi (U.S. Patent No. 4,523,432, filed Sep. 30, 1982) substantially disclosed the subject matter of claim 1, except for the preheated compressed air being heated only by heat from the thermal storage device and without burning fuel. However, in view of Frutschi’s disclosure that “[a]ir storage plants with so called ‘adiabatic operation’–i.e. operation without a gas turbine combustion chamber are known,” the examiner concluded that it would have been obvious to modify Frutschi’s air storage power station. Frutschi col. 1 ll. 39–52.

Specifically, the examiner found it would have been obvious to omit the combustion chambers and the recuperator of Frutschi in order “to heat the compressed air only by heat from the thermal storage device since it has been held that omission of an element and its function in a combination where the remaining elements perform the same function as before involves only routine skill in the art.” Examiner’s Answer, at 7 (mailed Nov. 29, 2011).

On appeal, finding that the examiner was apparently relying on In re Edge, 359 F.2d 896 (C.C.P.A. 1966) to support the rejection of claim 1, the Board concluded that the examiner’s reliance improper:

[B]ecause the Examiner’s analysis substitutes a per se rule of obviousness, namely, that omission of [an] element while retaining the function of the omitted element as a general proposition is not a patentable distinction, for an apparent reason to modify Frutschi’s system underpinned by a careful consideration of the facts.” Ex Parte Nakhamkin, at 5.

Additionally, the Board found the examiner erred by failing to provide a comparison between the facts of Edge and the facts of the underlying application to explain how the holding of Edge applies to the claims on appeal. Id.

Overall, the Board held that an examiner’s identification of a per se rule of obviousness is insufficient to satisfy the examiner’s burden to make a searching comparison of the claimed invention – including all its limitations – with the teaching of the prior art,” Ochiai, 71 F.3d 1572, since “rejections on obviousness grounds cannot be sustained by mere conclusory statements.” KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 417–418 (2007) (quoting In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006)). Instead, an examiner must compare the facts of the underlying application with the facts of the case relied on, and explain how the holding of the case applies to the pending claims.