Carbon Sequestration and Pore-Space Rights in Putnam County, Illinois

What EPA actually approved near Hennepin

In April 2026, the U.S. Environmental Protection Agency approved a Class VI Underground Injection Control permit for Marquis Carbon Injection LLC, a project tied to the Marquis Energy ethanol plant in Hennepin. The permit allows injection of up to 1.5 million metric tons of carbon dioxide per year, captured as a byproduct of ethanol production, for a six-year injection period. The CO2 would be stored roughly 3,094 feet underground, separated from the deepest underground source of drinking water by about 963 feet of rock, including a 404-foot-thick confining layer of shale and carbonate that EPA determined was sufficient to prevent the CO2 from migrating upward. EPA's approval requires Marquis to monitor the well not just during the six years of injection but for twelve additional years afterward, to confirm the CO2 stays where it was put and drinking-water sources remain protected.

The project has not been uncontroversial. Multiple articles from the Sierra Club's Illinois chapter have raised concerns about the injection well and the broader ethanol-plant expansion it's tied to, and the underlying EPA public-comment and permitting process reflects the kind of scrutiny that a first-of-its-kind (for this specific area) sequestration project tends to draw.

How Illinois law treats the underground space this project uses

This project intersects with a genuinely new part of Illinois property law: the Safety and Aid for the Environment in carbon capture and sequestration Act (the SAFE CCS Act), enacted in 2024. The Act does two things that matter directly to a landowner. First, it formalizes that title to "pore space" -- the underground void space in rock formations where CO2 or other substances get stored -- remains with the owner of the surface estate, and it explicitly bars severing pore-space ownership from the surface title the way mineral rights are commonly severed. In practice, that means you can't buy Putnam County land and discover someone else already owns the empty rock space thousands of feet beneath it, the way a prior owner might have sold off the coal or oil rights decades ago.

Second, the Act creates a "unitization" process for sequestration projects: an operator like Marquis has to obtain signed pore-space rights (through a lease or easement) from landowners covering at least 75% of the area it wants to use for storage before it can petition the state to compel the remaining "holdout" landowners into the project on set terms. Separately, the Illinois Commerce Commission retains authority to grant eminent domain for the construction of CO2 pipelines connecting a capture source (like an ethanol plant) to a storage site -- though new CO2 pipeline construction statewide is currently under a moratorium tied to federal PHMSA pipeline-safety rulemaking, meaning the pipeline side of this framework is less settled right now than the storage side.

What this means if you own or are buying land near Hennepin -- or anywhere else in Illinois

If a parcel sits within or near the geographic area covered by Marquis's storage facility permit, the practical question is whether that specific parcel's pore space has already been leased or optioned to the project, and on what terms -- a distinct question from surface ownership and from any existing oil, gas, or coal mineral-rights severance already on the title. If a parcel sits well outside any current project area, this still matters as forward-looking context: Illinois is actively building out its carbon-sequestration regulatory framework, and more projects of this kind are a realistic possibility across the Illinois Basin (which underlies much of downstate Illinois) in the years ahead.

• Pull the parcel's recorded chain of title and ask specifically about any pore-space lease, option, or easement -- these are a genuinely new instrument type in Illinois and may not be flagged by a standard title search the way a mineral-rights severance would be.
• If a parcel is anywhere near the Hennepin ethanol plant or the EPA-permitted injection area, ask the county Recorder's office and, separately, an Illinois-licensed attorney whether any unitization petition or pore-space agreement affecting that specific parcel has been filed.
• Understand that pore-space ownership under the SAFE CCS Act stays with the surface estate by default and cannot be severed going forward -- but confirm whether any agreement predating or contemporaneous with this framework already applies to a specific parcel.
• If you're a landowner being approached about a pore-space lease (near this project or a future one), have an attorney experienced in Illinois oil, gas, or carbon-capture law review the offer before signing -- the unitization mechanism means your consent isn't strictly required once an operator hits the 75% threshold, which changes the leverage calculus compared to a standard voluntary easement negotiation.

Bottom line

Carbon sequestration easements are a genuinely new category of subsurface right in Illinois, and Putnam County is currently one of the more concrete, dated, real-world examples of how the framework actually plays out on the ground. That doesn't make land near Hennepin risky to buy -- EPA's own review concluded the geology and well design should protect drinking water, and the SAFE CCS Act was specifically written to keep pore-space title with the surface owner rather than letting it be silently severed. But it does mean a parcel's pore-space status is now a real, checkable fact pattern worth asking about directly, alongside the more familiar mineral-rights and easement questions this project covers for other Illinois counties.