Sequestering In Place

by Luke Geiver (Ethanol Producer Magazine) Pipeline aggregation of ethanol plant CO2 has captured industry attention, but stand-alone CCS projects might be uniquely positioned for early success. -- Carbon capture and sequestration (CCS) projects are integrating into existing ethanol plants like never before. In the past two years, numerous plants in the heart of ethanol-production country—spanning several Midwest states—have announced their intentions to implement CCS. A majority of the projects announced will rely on pipeline networks to take compressed CO2 from participating ethanol plants to alternative locations where the gas will be utilized for industrial purposes or, more likely, injected thousands of feet below the surface.

A handful of plants are taking the steps—or already have—to explore the feasibility of capturing and storing CO2 onsite, or very close to the confines of the ethanol plant’s geographic footprint. Reviewing why and how those plants are approaching and dealing with the variables related to the process shows what it takes to sequester on location, autonomously.

The sequestration portion of CCS relies on the presence of a geologic formation capable of housing carbon gas molecules and trapping them. Every plant location is different in terms of the geologic formations below ground. In some areas, a suitable rock structure like sandstone or limestone may exist only 1,000 feet underground. In other cases, the target structure for CCS may be more than two miles down. The deeper the suitable formation, the costlier the upfront price.

in-place sequestration projects must start with the well permitting process. From there, a permitted well can be drilled by a reputable drilling company. The core samples from the drill-out will reveal the geologic formations below the surface. Although the geology is generally already understood for most areas in ethanol country, the process still has to be undertaken to ensure exactly what lies beneath. If the test well shows favorable geology, it can be used as the injection well. Other injection points can be added, along with the compression equipment needed to take CO2 from its gas state into the liquid state needed for injection. A monitoring system must also be installed.

In California, progressive renewable energy producer Aemetis has undergone the early test well phase.

The company’s study showed that more than 2 million metric tons of CO2 per year could be injected at its Keyes ethanol plant site.

In late 2021, Marquis Energy began drilling a 5,000-foot test well to determine the capacity available for carbon sequestration at the company’s planned industrial site in Hennepin, Illinois.

At Sterling Ethanol LLC and Yuma Ethanol LLC, Carbon America will help each capture and store roughly 95 percent of the CO2 emissions generated through the fermentation process. Carbon America will build, own and operate the systems in northeastern Colorado.

Rex American Resources Corp.’s Illinois ethanol plant, One Earth Energy, drilled its first test well in December 2021.

Near Underwood, Midwest AgEnergy Group (MAG) has been exploring the feasibility of a CCS well for its 70 MMgy Blue Flint ethanol plant.

RTE (Red Trail Energy) has already started constructing a capture facility adjacent to its ethanol plant that will push 180,000 metric tons of CO2 annually. Like the Marquis facility in Illinois, the RTE project will inject into sandstone.

At the plant, the CO2 exhaust from the fermentation vessels is set to be captured and piped to a capture facility next door. That exhaust is compressed and dehydrated to purify the CO2. The rest of the exhaust, mainly water vapor and oxygen, is released into the atmosphere.

At the gas capture plant, CO2 is compressed from 1,500 psi into liquid CO2 (which flows like water). The compressor, according to EERC’s design team working on the project, acts like a water tower, providing the pressure for the downhill flow into the injection well. Real-time, continuous fiber-optics monitors the entire path of the CO2.

While RTE awaits final approval to fully deploy its CCS system in North Dakota, the Summit Carbon Solutions pipeline project, backed by $1 billion in private equity, offers insight on who is out there to supply equipment.

For ethanol plants looking into onsite CCS, the early process involves drilling, sampling and data collection.

1. Obtain Permits: Drill holes for geologic research requires drilling permits. Every state has a geologic division with forms or answers on what is needed.

2. Prepare the Drill Site: Pad preparation usually requires leveling a space of 400 feet by 400 feet. The drilling rig needs a flat, workable surface. Pads usually take two weeks to construct.

3. Drill the Hole: Well drilling in the modern age is a multi-step process. Each stage includes adding casing or using drilling mud and cement to ensure that the downhole effect doesn’t impact existing freshwater sources.

4. Gather Downhole Data: After the shaft is drilled out and core samples of rock are collected, wireline trucks with sensors lower line into the well to gather more data. All of this is standard practice.

5. Close the Hole: Following data collection, test holes or wells are sealed temporarily while data is analyzed. READ MORE