NRG Energy Inc v. MidWest Energy EMiSSIons Corp

1. Case Identification

• Case #: IPR2020-00832
• Patent #: 10,343,114
• Filed: April 21, 2020
• Petitioner(s): NRG Energy, Inc., Talen Energy Corporation, and Vistra Energy Corp.
• Patent Owner(s): Midwest Energy Emissions Corp.
• Challenged Claims: 1-9, 12-30

2. Patent Overview

• Title: Method for Mercury Removal from Flue Gas
• Brief Description: The ’114 patent relates to methods for removing mercury from flue gas in facilities like coal-fired power plants. The claimed invention purports to combine two known techniques: the injection of bromine-containing species (e.g., HBr or Br₂) into the combustion chamber or onto the coal fuel source, and the separate, downstream injection of an activated carbon sorbent to capture the mercury.

3. Grounds for Unpatentability

Ground 1: Claims 1-2, 4-9, 12-28, and 30 are obvious over Sjostrom in view of Eckberg.

• Prior Art Relied Upon: Sjostrom (a Jan. 2005 conference presentation) and Eckberg (a Jan. 2005 conference presentation).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sjostrom taught the fundamental elements of the challenged claims, including a system for mercury control in coal-fired plants that uses both activated carbon sorbent injection and the addition of halogens, including bromine ("Br"). Sjostrom's diagrams depicted adding bromine at three potential locations: onto pulverized coal before the boiler (Location 1), directly into the combustion chamber (Location 2), and concurrently with the sorbent downstream (Location 3). While Sjostrom taught the general process, Petitioner asserted it lacked specific details on the chemical form of bromine to be used or its injection parameters. Eckberg allegedly supplied these missing details. Eckberg described a similar process of injecting halogens into a coal-fired boiler and specifically taught using an aqueous solution of calcium bromide (CaBr₂), providing explicit data on bromine-to-coal ratios, solution feed rates, and resultant bromine concentrations in the flue gas.
  • Motivation to Combine: A POSITA would combine Sjostrom and Eckberg because both references addressed the identical problem of mercury removal using bromine and activated carbon. Petitioner highlighted that the two presentations were delivered consecutively in the same technical session at the 2005 Electric Utilities Environment Conference (EUEC), shared a common author, and involved a common research partner (EPRI). This context would lead a POSITA to view the references as complementary, with Eckberg providing the specific, practical implementation details for the general system outlined in Sjostrom.
  • Expectation of Success: A POSITA would have had a high expectation of success because the references described nearly identical processes and equipment configurations. Combining Eckberg’s specific teaching of using calcium bromide with Sjostrom's system would be a straightforward application of a known chemical substance to a known process to achieve a predictable result.

Ground 2: Claims 1-9 and 12-30 are obvious over Sjostrom in view of Olson-646.

• Prior Art Relied Upon: Sjostrom (a Jan. 2005 conference presentation) and Olson-646 (Application # 2006/0048646).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground again used Sjostrom as the primary reference for the overall system. Petitioner argued that Olson-646, like Eckberg, provided the necessary missing details but focused more on the underlying chemistry and specific reactive species. Olson-646 explicitly taught using gaseous hydrogen bromide (HBr) or molecular bromine (Br₂) as the promoter. It further detailed the chemical reaction mechanisms, explaining how bromine species react with activated carbon to form a "promoted sorbent" that is highly effective at oxidizing and capturing mercury. Olson-646 also disclosed specific, workable ranges for the promoter-to-sorbent ratio (e.g., 1 to 30 grams of promoter per 100 grams of carbon) and described a feedback control loop using a continuous emissions monitor (CEM) to control the injection rates.
  • Motivation to Combine: A POSITA would combine Sjostrom with Olson-646 to understand the specific chemical compounds and reactions to optimize the process Sjostrom described. Where Sjostrom generically referred to "Br," Olson-646 provided the specific, highly reactive forms (HBr, Br₂) and the scientific rationale for their effectiveness. Both references taught using bromine to enhance activated carbon for mercury removal, and both cited the same commercial sorbent (Norit Darco FGD), reinforcing their compatibility.
  • Expectation of Success: The combination was expected to succeed because both references targeted the same goal and demonstrated high mercury removal efficiencies (over 70%). Applying the specific chemical species and process control logic from Olson-646 to the established system in Sjostrom represented a routine optimization by a POSITA using known principles to achieve a predictable improvement in performance.

4. Key Technical Contentions

• Priority Date Challenge: A central argument of the petition was that the ’114 patent was not entitled to claim priority to any application filed before May 14, 2018. This argument was critical because all asserted prior art references (Sjostrom, Eckberg, and Olson-646) predate 2018.
• Lack of Written Description Support: Petitioner asserted that the key limitations of the independent claims—specifically, adding bromine species (Br₂, HBr, Br⁻) to the coal or into the combustion chamber upstream of the sorbent injection—were "Newly-Introduced Limitations" that lacked adequate written description support in any of the parent applications in the priority chain. Petitioner argued that prior to the 2018 application that matured into the ’114 patent, the specifications did not disclose these specific injection points for these specific chemicals with enough clarity for a POSITA to conclude the inventors were in possession of the invention. The disclosures in earlier applications were described as either too vague (e.g., a diagram showing a generic "additive" injection) or fundamentally different from the claimed methods.

5. Arguments Regarding Discretionary Denial

• Arguments Against §314(a) Denial (Fintiv): Petitioner argued that discretionary denial based on the co-pending district court litigation would be inappropriate. It was contended that the litigation had "barely begun," with no answer to the complaint filed, no scheduling order issued, and no discovery commenced. Therefore, a Final Written Decision in the IPR would likely issue well before a potential trial date.
• Arguments Against §325(d) Denial: Petitioner also argued against denial under §325(d), which allows the Board to reject petitions raising art previously considered by the USPTO. It was asserted that the primary references, Sjostrom and Eckberg, were never presented to or considered by the examiner during prosecution. While Olson-646 was listed among many other references in the ’114 patent, Petitioner argued it was never substantively used in a rejection, and thus the arguments based upon it were new to the Office.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-9 and 12-30 of Patent 10,343,114 as unpatentable.