Technoeconomic analysis of carbon dioxide-to-fuel in corn ethanol plants

Will Northrop

This research seeks to set the groundwork for large-scale projects to capture carbon dioxide (CO2) emitted from corn ethanol plants and convert it to renewable fuels using solar or wind energy. In the project, the University of Minnesota (UMN) will collaborate with the Chippewa Valley Ethanol Company (CVEC) plant to determine the energy and cost benefits of converting waste CO2 to methanol and socalled “e-gasoline”, a hydrocarbon blend with similar properties to petroleum-derived gasoline. The primary goals of the one-year effort will be to determine the energy requirements, capital costs and financial benefits of installing a CO2-to-fuel system as an external facility attached to one or multiple corn ethanol plants. As part of the work scope, different blending levels of e-gasoline with ethanol will be considered from using the generated fuel as a denaturant through creating a fully renewable blending stock to create renewable E85. Additional modeling work will estimate the benefits of custom renewable E85 blends on spark-ignition engine efficiency and CO2 emissions.

In executing the proposed work, the UMN team will conduct stakeholder interviews with CVEC staff to understand the composition, flow rate, and time-varying behavior of the CO2 exhaust stream from the plant. A computer process model using Aspen Plus developed under a previous funded projects will be used to simulate the plant and generate input for additional simulations to be created in the project. Methanol synthesis from renewably produced hydrogen and catalytic methanol to gasoline processes will be modeled. Available data for hydrogen production from water and renewable electricity, methanol synthesis, and M2G will be used with cost input from companies installing such systems. At the end of the proposed project, the UMN team will recommend pathways forward for how best to implement CO2-to-fuel using stranded wind resources and CO2 captured from ethanol plants in Minnesota.