PTAB

IPR2025-00280

Berkshire Hathaway Energy Company v. MES, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Method for Reducing Mercury in a Mercury-Containing Gas
  • Brief Description: The ’517 patent relates to methods for removing mercury from flue gas generated by coal combustion. The claimed invention involves adding bromine-containing ingredients to the coal or combustion chamber and subsequently collecting the mercury from the flue gas using an activated carbon sorbent.

3. Grounds for Unpatentability

Ground 1: Obviousness over Vosteen589 and Starns - Claims 1-15 and 17-30 are obvious over Vosteen589 in view of Starns.

  • Prior Art Relied Upon: Application # US2004/0013589 (“Vosteen589”), Travis Starns, “Full-Scale Test of Mercury Control with Sorbent Injection...” (June 2002) (“Starns”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Vosteen589 taught the core method of adding a bromine compound to coal before combustion to facilitate mercury removal from flue gas using a dry sorbent like activated carbon. However, Vosteen589 lacked specific implementation details. Starns, a conference paper describing full-scale power plant tests, supplied the missing details, teaching the injection of powdered activated carbon (PAC) into the flue gas upstream of a particulate control device (an electrostatic precipitator, or ESP) to capture mercury. The combination of Vosteen589’s chemical approach with Starns’s well-known mechanical injection system rendered the claims obvious.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Vosteen589 with Starns to implement Vosteen589’s conceptual process using the mature, practical, and well-documented activated carbon injection (ACI) technology described in Starns. Both references addressed the same problem—mercury removal from coal-fired power plants—and were interoperable.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because combining a known chemical additive (bromine from Vosteen589) with a standard injection method for a known sorbent (activated carbon from Starns) involved using prior art elements for their known purposes to achieve a predictable result.

Ground 2: Obviousness over Vosteen589 and Mass-EPA - Claims 1-15 and 17-30 are obvious over Vosteen589 in view of Mass-EPA.

  • Prior Art Relied Upon: Vosteen589, Massachusetts Dep. of Environmental Protection, “Evaluation of...Controlling and Eliminating Mercury Emissions...” (Dec. 2002) (“Mass-EPA”).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground presented a similar argument to Ground 1, with the Mass-EPA report serving the same role as Starns. Vosteen589 taught adding bromine to coal to aid mercury capture by activated carbon. Mass-EPA, a government report on the feasibility of mercury control technologies, taught that ACI was a mature, commercially ready technology for mercury removal. Mass-EPA explicitly described injecting activated carbon into the exhaust system for subsequent collection by a particulate control device and identified it as the most likely candidate for commercialization.
    • Motivation to Combine: A POSITA would be motivated to use the ACI technology detailed in the Mass-EPA report as a practical way to implement the chemical process of Vosteen589. Mass-EPA expressly stated a goal of “improving carbon to mercury injection rates and reducing control costs,” providing an explicit reason to combine an efficiency-improving additive like bromine (from Vosteen589) with the ACI systems it evaluated.
    • Expectation of Success: Success was predictable because Mass-EPA confirmed that ACI was a well-understood technology. Applying Vosteen589's bromine additive to this established system would be a routine optimization to enhance mercury removal efficiency.

Ground 3: Anticipation by Downs-Boiler - Claims 1, 4, 6-7, 11-15, 17, 22, and 25-29 are anticipated by Downs-Boiler.

  • Prior Art Relied Upon: Application # US2008/0107579 (“Downs-Boiler”).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Downs-Boiler disclosed every element of the challenged claims. Downs-Boiler taught a method of reducing mercury from coal combustion flue gas by adding a bromine-containing reagent (e.g., CaBr₂, HBr, Br₂) to the coal before it entered the combustion chamber. It further taught injecting a powdered activated carbon (PAC) sorbent into the flue gas downstream of the boiler to adsorb the mercury, which was then collected by a particulate collector (e.g., an ESP or fabric filter). Downs-Boiler also disclosed applying the method to various coal types (including subbituminous and lignite) and achieving over 70% mercury removal.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations of Downs-Boiler with Starns (Ground 4) and Downs-Boiler with Mass-EPA (Ground 5). These grounds argued that even if Downs-Boiler did not anticipate the claims, it rendered them obvious for the same reasons as in Ground 3, and that Starns and Mass-EPA further confirmed the obviousness of using standard ACI hardware and control processes.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued the Board should not discretionarily deny institution under §314(a) based on Fintiv factors because the parallel district court proceeding had just begun. No answers had been filed, no scheduling orders were in place, and discovery had not opened. An FWD from the IPR would likely issue before any potential trial.
  • Petitioner also argued against denial under §325(d), asserting that the examiner erred by overlooking key prior art. Although Vosteen589 and Downs-Boiler were cited on the face of the ’517 patent, they were never used in a substantive rejection. More importantly, the primary secondary references for the obviousness grounds, Starns and Mass-EPA, were never presented to or considered by the Office.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-15 and 17-30 of Patent 10,596,517 as unpatentable.