PTAB

IPR2025-00280

Berkshire Hathaway Energy Co v. MES Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Reducing Mercury in Gas
  • Brief Description: The ’517 patent discloses methods for removing mercury from flue gas produced by coal combustion. The methods involve adding a bromine-containing additive to the coal before it enters the combustion chamber and subsequently collecting mercury from the resulting gas stream using an activated carbon sorbent.

3. Grounds for Unpatentability

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

  • Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Starns (a 2002 conference paper).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Vosteen589 discloses the core method of independent claim 1: adding a bromine-containing additive (e.g., HBr, NaBr) to coal upstream of a combustion chamber to form mercury-containing gas, and then collecting the mercury using an activated carbon sorbent in a downstream dry emission control system. However, Vosteen589 lacked specific implementation details for adding the sorbent. Starns allegedly supplied these missing details, describing the injection of powdered activated carbon (PAC) into flue gas upstream of a particle control device (e.g., an electrostatic precipitator or ESP) as the "most mature, retrofit technology" available. Starns also taught controlling the mercury removal by modifying the sorbent injection rate based on measured mercury content, addressing limitations of claims 8-10.
    • Motivation to Combine: A POSITA would combine the teachings of Vosteen589 and Starns to implement Vosteen589’s chemical treatment method using the well-known, mature, and practical hardware and control processes for activated carbon injection (ACI) detailed in Starns. This combination would predictably improve mercury removal.
    • Expectation of Success: Because ACI was a mature technology for mercury control and the references address the same problem in the same field, a POSITA would have had a high expectation of success in combining them to achieve predictable results.

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

  • Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Mass-EPA (a 2002 Massachusetts Department of Environmental Protection report).
  • Core Argument for this Ground:
    • Prior Art Mapping: The argument largely mirrored Ground 1, with Vosteen589 providing the primary method of bromine addition to coal and subsequent capture with activated carbon. Mass-EPA, like Starns, allegedly supplied the known technique of sorbent injection. Mass-EPA described activated carbon as the "most extensively studied sorbent" and ACI as a key technology for mercury control, ready for commercialization. The report explicitly discussed co-injecting activated carbon with alkaline sorbents (e.g., lime), mapping to the limitations of claims 2-3.
    • Motivation to Combine: A POSITA would have been motivated to combine Vosteen589 with Mass-EPA for the same reasons as with Starns—to apply a practical injection method to Vosteen589’s system. Mass-EPA provided an express motivation by stating that "improving mercury adsorption efficiency of activated carbons has been ongoing with the goal of...reducing control costs," a goal achieved by using Vosteen589's halogen treatment with the ACI process.
    • Expectation of Success: Success was predictable because the combination involved applying a known sorbent delivery system (ACI) to a compatible chemical treatment process to achieve the known goal of enhanced mercury removal.

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

  • Prior Art Relied Upon: Downs-Boiler (Application # 2008/0107579).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Downs-Boiler disclosed every limitation of the challenged claims. It taught a method for reducing mercury from coal combustion flue gas by adding a bromine-containing reagent (e.g., CaBr₂, HBr, or Br₂) to the coal before it enters the combustion chamber (at "Points A, B") or directly into the furnace (at "Point C"). Downs-Boiler further disclosed injecting a powdered activated carbon (PAC) sorbent into the flue gas downstream of the combustion chamber but upstream of a particulate collector (an ESP or fabric filter) to adsorb and collect the mercury. Petitioner argued Downs-Boiler also explicitly disclosed using subbituminous and lignite coals (claims 11-12) and achieving greater than 70% mercury removal (claims 6-7), showing a 77% reduction in its figures.

  • Additional Grounds: Petitioner asserted obviousness challenges for claims 1, 4-15, and 17-30 over Downs-Boiler in view of Starns (Ground 4) and Downs-Boiler in view of Mass-EPA (Ground 5). These grounds argued that even if Downs-Boiler did not anticipate every limitation, a POSITA would have combined its teachings with the practical ACI details from Starns or Mass-EPA to arrive at the claimed invention.

4. Arguments Regarding Discretionary Denial

  • §314(a) (Fintiv): Petitioner argued against discretionary denial under Fintiv, contending that the parallel district court litigation was in its earliest stages. At the time of filing, no Petitioner had filed an answer, discovery had not opened, and no trial date had been set, ensuring the Final Written Decision would issue long before any potential trial.
  • §325(d): Petitioner argued that denial would be improper because the examiner materially erred during prosecution. The key secondary references, Starns and Mass-EPA, which are used in every obviousness ground, were never presented to or considered by the PTO. Furthermore, while Vosteen589 and Downs-Boiler were listed on the face of the ’517 patent, the examiner never used them in a substantive rejection, thereby overlooking their most pertinent teachings.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-15 and 17-30 of the ’517 patent as unpatentable.