Perhaps you are familiar with the bubbles in beer. Carbon dioxide is a natural byproduct from the fermentation of any feedstock into ethanol, whether it is hops, barley, grapes, or malt. When corn is fermented into ethanol at large scale, carbon dioxide can be captured at large scale as well. This process is relatively cheap and easy relative to other CO2 abatement processes, because the CO2 is quite concentrated. As a result, many ethanol production plants already capture CO2, selling the material into the carbonation market, and into enhanced oil recovery, or storing it.
As an example, Archer Daniels Midland (ADM) built a large project in Decatur, Illinois, which successfully captured and stored 1MT of CO2 from 2011 to 2014. The project then advanced to the larger-scale Illinois Industrial Carbon Capture and Storage (IL-CCS) plant, built in 2017, which had a 1Mt/yr capturing and storing capacity. The ADM biofuel plant produced >99% pure CO2 stream as a by-product of fuel-grade ethanol production, which was used in CCS. The plant itself produced 4.5X more CO2 than the capacity of the capture plant, which was sized based on the market for CO2 more than as a demonstration of full abatement.
The project cost $208 million, of which $141.4 million came via the US DOE’s CCS grants, and was 68% government-funded. The CCS facility performed at about half of its designed capacity in 2020, but ADM appears to be committed to continuing it, signing a deal with Wolf Carbon to build a pipeline to a central storage location which may be used by other capture projects in the region.
If we assume the plant can operate at its original designed capacity, then the capex of about $200/ton/yr, then at a working average cost of capital of 10%, the cost of the capex will be just $20/ton amortized over 30 years. Capture costs of $30/ton thus seem achievable, with additional costs for injection. At these rates, the tax credits in the Inflation Reduction Act are large enough to pay off projects in just the 12 years during which tax credits are currently offered.
The main risk for building carbon capture for ethanol plants is not the economics of operation, but whether demand for ethanol will continue to remain high in the future. Given the US political scene, that appears to be a decent bet. These carbon capture facilities, and the regional sequestration hubs that support them, are in good technical and economic shape.
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