Berkshire Hathaway Energy Co v. MES Inc

1. Case Identification

• Case #: IPR2025-00422
• Patent #: 10,668,430
• Filed: February 11, 2025
• Petitioner(s): Berkshire Hathaway Energy Company, Interstate Power & Light Company, MidAmerican Energy Company, PacifiCorp, WEC Energy Group, Inc., and Wisconsin Power & Light Company
• Patent Owner(s): Birchtech Corp.
• Challenged Claims: 1-4, 6-29

2. Patent Overview

• Title: Method for Separating Mercury from Mercury-Containing Gas
• Brief Description: The ’430 patent relates to methods for removing mercury from flue gas generated by coal combustion. The claimed method involves adding a bromine-containing additive to coal before or during combustion and subsequently injecting an activated carbon sorbent downstream to capture the mercury for later separation.

3. Grounds for Unpatentability

Ground 1: Obviousness over Vosteen589 and Starns - Claims 1-4 and 6-29 are obvious over Vosteen589 in view of Starns.

• Prior Art Relied Upon: Vosteen589 (Application # 2004/0013589) and Starns (a June 2002 conference paper).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Vosteen589 disclosed the core method of adding bromine or a bromine compound directly to coal before combustion to improve mercury removal from flue gas at coal-fired power stations. Vosteen589 further taught using a downstream "dry emission control system" with an activated carbon sorbent to adsorb the oxidized mercury. However, Vosteen589 lacked specific implementation details for the sorbent injection. Starns, a publicly available conference paper, provided these missing details by describing the "most mature, retrofit technology" for mercury control: injecting powdered activated carbon (PAC) into the flue gas upstream of a particle collector, such as an electrostatic precipitator (ESP). Starns detailed the necessary injection equipment (silos, blowers), control systems (PLCs), and operational variables, such as adjusting the sorbent injection rate to control mercury removal.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the teachings of Vosteen589 and Starns to implement an effective mercury removal system. A POSITA seeking to apply Vosteen589’s chemical enhancement process would have looked to a practical, mature, and well-documented technology like the activated carbon injection (ACI) system described in Starns to supply the necessary implementation details.
  • Expectation of Success: The combination represented the use of a known injection method (Starns) to implement a known chemical process (Vosteen589) to achieve a predictable result—the efficient removal of mercury from flue gas.

Ground 2: Anticipation by Downs-Boiler - Claims 1-4, 6-9, 14-16, 18-19, and 22-28 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. Downs-Boiler taught a method for enhanced mercury removal from flue gas by adding a bromine-containing reagent (e.g., HBr, CaBr2) at various points, including directly to crushed or pulverized coal before it enters the combustion chamber (a boiler/furnace) or directly into the combustion zone itself. Downs-Boiler explicitly disclosed the subsequent downstream injection of a powdered activated carbon (PAC) sorbent to contact and adsorb mercury. This sorbent, now laden with mercury, was then separated from the flue gas using a downstream particulate collector, such as an ESP or fabric filter. The reference further disclosed its applicability to various coal types, including subbituminous and lignite, and demonstrated mercury removal rates exceeding the claimed 70% threshold.

Ground 3: Obviousness over Downs-Boiler and Mass-EPA - Claims 1-4 and 6-29 are obvious over Downs-Boiler in view of Mass-EPA.

• Prior Art Relied Upon: Downs-Boiler (Application # 2008/0107579) and Mass-EPA (a December 2002 government report).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Downs-Boiler taught the foundational process of adding bromine to coal to enhance mercury capture by a downstream PAC injection system. While Downs-Boiler disclosed the core components, Mass-EPA, a government report on the feasibility of mercury control technologies, provided further details and motivation for optimizing such a system. Mass-EPA described ACI as a well-understood technology ready for commercialization and discussed its use at coal-fired electric utility plants. Crucially, Mass-EPA taught continuously monitoring mercury emissions and modifying sorbent injection rates as a function of measured mercury content to achieve target removal rates (e.g., 75%) and reduce costs.
  • Motivation to Combine: A POSITA implementing the system in Downs-Boiler would have been motivated to consult a publicly available technical report like Mass-EPA for guidance on hardware, control processes, and optimization. Mass-EPA provided an express motivation to improve efficiency and reduce costs, which would lead a POSITA to incorporate its teachings on monitoring and adjusting injection rates into the Downs-Boiler process.
  • Expectation of Success: Applying the well-known control and optimization strategies for ACI systems detailed in Mass-EPA to the bromine-enhanced mercury capture process of Downs-Boiler was a straightforward combination of known elements that would predictably yield an efficient and cost-effective mercury removal system.
• Additional Grounds: Petitioner asserted additional obviousness challenges based on the combination of Vosteen589 and Mass-EPA (Ground 2) and the combination of Downs-Boiler and Starns (Ground 4), relying on similar theories of combining a primary chemical treatment reference with a secondary reference providing practical implementation and optimization details for ACI systems.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not discretionarily deny institution. Under the Fintiv factors, the parallel district court proceedings were in their earliest stages with no trial dates set, and a Final Written Decision would likely issue before any trial.
• Under §325(d), Petitioner contended that the examiner had not previously considered the most relevant prior art. The Starns and Mass-EPA references, used in every obviousness combination, were never before the examiner. While Vosteen589 and Downs-Boiler were listed on the face of the ’430 patent, the examiner did not use them in any substantive rejection, which Petitioner characterized as a material error of overlooking specific, relevant teachings.

5. Relief Requested

• Petitioner requests institution of IPR and cancellation of claims 1-4 and 6-29 as unpatentable.