Term ended Aug 22, 2025 · High confidence
20-year base term ended Aug 22, 2025
USPTO later recorded it as expired for non-payment on Oct 5, 2026.
Held by Birchtech Corp.
Filed Aug 14, 2013 as application 13/966,768 · Granted Sep 2, 2014
Base term, 20 years from filing
Today
Term ended Aug 22, 2025
2005
2026
Clock starts
Aug 22, 2005
Aug 22, 2005
Term ended
Aug 22, 2025
Aug 22, 2025
Granted
Sep 2, 2014
Sep 2, 2014
base term
after the term ends
fee events
Updated Nov 14, 2026 · includes USPTO assignment & status data published Nov 14, 2026 and grant & fee data published Nov 10, 2026 (weekly) · how we know
None
Term adjustment
No prosecution delay on this record.
No effect
Terminal disclaimer
Resolved from the filed document, referencing US 8,168,147, US 8,512,655, to Aug 22, 2025. The term already ends on or before that date, so the cap shortened nothing.
2 of 2
Maintenance fees paid
Two maintenance fees can end this term early, the ones due 3.5 and 7.5 years from grant; the third one's grace period runs past the term end. This counts the ones the record shows paid.
28
Family applications on record here
Applications sharing this one's continuity chain whose file history this site holds. The family may have others.
This patent's term is its 20-year base term, with no adjustment for prosecution delay. A terminal disclaimer is resolved from the filed document, and it ends no earlier than this term, so it shortens nothing. Confidence: High. from the record
How we calculated this date
One row per rule, each showing its own input and what it did to the date. A step we could not verify says so instead of resolving itself.
| Step | Input | Date after this step | Confidence |
|---|---|---|---|
| Base term, 20 years from filing | Clock starts Aug 22, 2005, when application 11/209,163, the earliest non-provisional in its chain, was filed (this one was filed Aug 14, 2013) | Aug 22, 2025 | High confidence |
| Continuity chain | Every parent in the chain resolved | no change | High confidence |
| Patent term adjustment | None on file | no change | High confidence |
| Terminal disclaimer cap | Disclaimer resolved from the filed document (refs US 8,168,147, US 8,512,655) | resolves to Aug 22, 2025, no earlier than this term, so no change | High confidence |
| Patent term extension | None on file | no change | High confidence |
| Fee events | 2 of 2 maintenance fees paid | term ended | High confidence |
| USPTO status record | Recorded as expired for non-payment on Oct 5, 2026, after the term ended | no change | High confidence |
| Computed term end | The steps above, in order | Aug 22, 2025 | High confidence |
This family
| US 7,435,286 | Term ended Mar 2026 | Mar 2026 |
| US 8,173,566 | Term ended Oct 2026 | Oct 2026 |
| Application 12/201,595 | Abandoned not computed | not computed |
| US 8,168,147 | Term ended Aug 2025 | Aug 2025 |
| US 8,652,235 | Term ended Jan 2026 | Jan 2026 |
| US 8,440,585 | Lapsed on the fee record May 2021 | May 2021 |
| US 8,512,655 | Term ended Aug 2025 | Aug 2025 |
| US 8,821,819 | this patent Aug 2025 | Aug 2025 |
8 of 28 applications in this family shown, earliest filings first. The applications whose file history this site holds. The family may have others.
Assignments
Assignment documents as recorded at the USPTO, oldest first, with the reel and frame each was recorded at. A recorded assignment is a filed document, not a statement of current ownership, and the absence of a later one is not evidence that the last one still stands.
| Recorded | Assignor | Assignee | Conveyance |
|---|---|---|---|
| Aug 29, 2014 Reel 33643, frame 339 | Pavlish, John H. | Energy and Environmental Research Center Foundation | Assignment of Assignor's Interest |
| Aug 29, 2014 Reel 33643, frame 436 | Olson, Edwin S. | Energy and Environmental Research Center Foundation | Assignment of Assignor's Interest |
| Aug 29, 2014 Reel 33643, frame 538 | Holmes, Michael J. | Energy and Environmental Research Center Foundation | Assignment of Assignor's Interest |
| Sep 9, 2014 Reel 33698, frame 612 | Olson, Edwin S. | Energy and Environmental Research Center Foundation | Corrective Assignment to Correct the Receiving Party's Address Previously Recorded on Reel 033643 Frame 0436. Assignor(S) Hereby Confirms the Assignment. |
| Jun 8, 2017 Reel 42647, frame 351 | Energy and Environmental Research Center Foundation | Midwest Energy Emissions Corp. | Assignment of Assignor's Interest |
| Mar 11, 2020 Reel 52144, frame 657 | Energy and Environmental Research Center Foundation | Midwest Energy Emissions Corp. | Corrective Assignment to Correct the Correct the Address of the Receiving Party Previously Recorded on Reel 042647 Frame 0351. Assignor(S) Hereby Confirms the Assignment. |
| Nov 7, 2024 Reel 69187, frame 413 | Midwest Energy Emissions Corp. | Birchtech Corp. | Change of Name |
Sources
Google Patents · The patent document at USPTO · Assignment records at USPTO
USPTO account required: This application in Patent Center · USPTO's maintenance fee lookup
Maintenance fee events come from USPTO's own fee records. Its fee lookup asks for the patent number and the application number.
Terminal disclaimer
A terminal disclaimer resolved from the filed document, referencing US 8,168,147, US 8,512,655, ends no earlier than this term, so it caps nothing.
Citations
34
later US patents cite this one
That is top 25% of utility patents granted in 2014 in our data, the only group it is compared against.
How we rank
Every date shows its work: the base term, any term adjustment or extension, any disclaimer cap, and the maintenance fee record, each with a confidence tier. How this record was built
Computed patent terms end on the dates shown. Related patents and pending applications may cover overlapping subject matter.