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 and 12-30

2. Patent Overview

• Title: Mercury Removal from Flue Gas
• Brief Description: The ’114 patent relates to methods for removing mercury from flue gas generated during coal combustion. The disclosed invention combines two known techniques: adding a bromine-containing species to the coal or directly into the combustion chamber, and subsequently injecting an activated carbon sorbent downstream of the combustion chamber to capture the mercury.

3. Grounds for Unpatentability

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

• Prior Art Relied Upon: Sjostrom (a January 2005 conference presentation) and Eckberg (a January 2005 conference presentation).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sjostrom taught the fundamental framework of the challenged claims, including the addition of a generic halogen ("Br") at multiple locations (onto pulverized coal, into the combustion chamber, or with the sorbent) combined with downstream injection of activated carbon sorbent to remove mercury from flue gas. However, Sjostrom did not specify the chemical form of the bromine or its injection rate. Eckberg disclosed these missing details, teaching the injection of a specific bromine compound (an aqueous solution of calcium bromide, CaBr2) directly into a boiler and providing data on the bromine-to-coal ratio and feed rates.
  • Motivation to Combine: A POSITA would combine these references because they addressed the identical problem of mercury removal and were presented consecutively at the same technical conference session (2005 EUEC), even sharing a common author. A skilled artisan would have looked to Eckberg to provide the specific, readily available chemical compounds and implementation parameters needed to practice the general method disclosed in Sjostrom.
  • Expectation of Success: A POSITA would have had a high expectation of success because the references described nearly identical processes. Combining Eckberg's specific teachings with Sjostrom’s system required no significant modification to the overall process or equipment.

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

• Prior Art Relied Upon: Sjostrom (a January 2005 conference presentation) and Olson-646 (Application # 2006/0048646).
• Core Argument for this Ground:
  • Prior Art Mapping: As in Ground 1, Sjostrom provided the foundational process. Petitioner asserted that Olson-646 supplied alternative and additional technical details, teaching the use of specific bromine species like gaseous hydrogen bromide (HBr) or molecular bromine (Br2) to create a "promoted" activated carbon sorbent. Olson-646 also described the underlying chemical reactions between bromine, carbon, and mercury. Furthermore, it taught a control system where a continuous emissions monitor provides feedback to control the injection rates of both the sorbent and the halogen promoter to maintain mercury levels below a desired threshold.
  • Motivation to Combine: A POSITA would combine Sjostrom with the ’646 application to identify specific, highly reactive bromine species (HBr or Br2) and to understand the chemical mechanisms for improving mercury capture. Both references teach achieving over 70% mercury removal and use the same commercial activated carbon (Norit Darco FGD), signaling their compatibility. Olson-646 provided a roadmap for optimizing the process Sjostrom disclosed.
  • Expectation of Success: Success was predictable, as the combination involved applying the known chemical species and well-known feedback control methods from Olson-646 to the established system of Sjostrom to achieve a known result.

4. Key Technical Contentions (Beyond Claim Construction)

• Petitioner contended that the ’114 patent is not entitled to its claimed 2004 priority date and that its effective filing date is no earlier than May 14, 2018. The argument centered on an alleged lack of written description support in the parent applications for essential limitations of the independent claims, specifically the addition of particular bromine-containing species (Br2, HBr, Br-, or a bromide compound) to the coal upstream of the combustion chamber.
• Because the priority chain was allegedly broken, Petitioner argued that the Sjostrom (2005), Eckberg (2005), and Olson-646 (2006) references all qualify as prior art under 35 U.S.C. §102.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §314(a) was inappropriate because the parallel district court proceeding had "barely begun." At the time of filing, motions to dismiss were pending, no scheduling order had been issued, and discovery had not commenced, ensuring that an inter partes review (IPR) would conclude well before any potential trial.
• Petitioner also argued against denial under §325(d), asserting that the Examiner did not previously consider the same art or arguments. The primary references of Sjostrom and Eckberg were never before the Examiner. While Olson-646 was listed in a citation disclosure, it was never used in a substantive rejection, and its teachings were not substantively evaluated during prosecution.

6. Relief Requested

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