Term ended Jan 23, 2026 · Medium confidence
20-year base term ended Aug 22, 2025
Why Medium: A parent in the chain could not be resolved.
USPTO later recorded it as expired for non-payment on Mar 23, 2026.
Held by Birchtech Corp.
Filed Apr 23, 2009 as application 12/429,058 · Granted Feb 18, 2014
Base term plus 154 days of patent term adjustment (USPTO delay)
Today
Term ended Jan 23, 2026
2005
2026
Clock starts
Aug 22, 2005
Aug 22, 2005
Term ended
Jan 23, 2026
Jan 23, 2026
Granted
Feb 18, 2014
Feb 18, 2014
base term
patent term adjustment
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
154
Days of term adjustment
Read from the USPTO patent term adjustment record, not recalculated here.
None
Terminal disclaimer
No disclaimer on this record.
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 runs 154 days past its 20-year base term on prosecution delay. Confidence: Medium. 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 Apr 23, 2009); a parent in its chain could not be resolved (the next row) | Aug 22, 2025 | High confidence |
| Continuity chain | A parent in the chain could not be resolved | dated from this application's own claim | Medium confidence |
| Patent term adjustment | +154 days, USPTO patent term adjustment record | Jan 23, 2026 | High confidence |
| Terminal disclaimer cap | None on record | no cap applied | 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 Mar 23, 2026, after the term ended | no change | High confidence |
| Computed term end | The steps above, in order | Jan 23, 2026 | Medium 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 | this patent 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 | Term ended 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 |
|---|---|---|---|
| Dec 12, 2011 Reel 27395, frame 863 | Energy & Environmental Research Center Foundation | Energy, United States Department Of | Confirmatory License |
| Oct 16, 2013 Reel 31416, frame 696 | Pavlish, John; Olson, Edwin; Holmes, Michael | Energy & Environmental Research Center Foundation | Assignment of Assignor's Interest |
| 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 |
| 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.
What's changing
Note
The 154 days of patent term adjustment (USPTO delay) are read from the USPTO record, not recalculated by us
Citations
54
later US patents cite this one
That is top 10% 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.