February 26, 2021
The internal combustion engine will be with society for a long time, regardless of the push to electric vehicles. Is there a way to achieve net-zero carbon impact with those engines? For one upstart, the answer is: yes.
Gevo, a Colorado-based firm, is working to build what it calls Net-Zero 1 near Lake Preston, S.D. "We are capturing renewable energy and transforming it into energy-dense liquids," CEO Patrick Gruber says. "The transportation industry knows it will need liquid fuels and that a net-zero footprint is good; that resonates with the industry."
The road to net-zero involves looking at the entire life cycle of the process. Gruber says the company is using an analysis model developed by Argonne National Laboratories called Greenhouse gases, Regulated Emissions and Energy Use in Technologies. GREET shows that agriculture's capture of carbon and use of atmospheric carbon count for something, especially when combined with renewable energy.
That growing corn plant uses atmospheric carbon as part of its photosynthetic process. Once that carbon is turned into corn, Gevo uses the feedstock to create the energy-dense liquids, such as gasoline or jet fuel. But as you analyze the process, where strip till and reduced tillage keep carbon in the soil, the life cycle of the farm counts for something more.
"Most people who know nothing about farming still have the paradigm that farming pollutes, agriculture pollutes, and that's just wrong. That is not what happens," Gruber says. "It's changed over the last 15 years, and people do not know that."
That measure of carbon impact helps build the story for this new approach to making the fuel. Isobutanol and other products Gevo makes are "drop in" replacements for petroleum-based fuels. The company is already making jet fuel from corn that's indistinguishable from the petroleum product in its fermentation plant near Luverne, Minn. And in Silsbee, Texas, a demonstration plant is where early work on the fuel-making process got its start. But it's time to move up.
New plant, net-zero impact
Gevo has long looked at the life-cycle analysis of its process. How is the corn grown? What happens to the corn protein and oil once the starches are removed? And what about the electricity the plant needs? What about the energy to run the boilers?
With construction set to begin in 2022, the new Lake Preston plant will look at processes from start to finish, and potentially eliminate fossil-based energy from its production process.
One difference in the Gevo process versus the ethanol process most farmers understand is the feed the plant generates. "We're planning on maximizing the protein coming out of the plant and it goes into the food chain, and we're taking the residual carbohydrates and converting them into hydrocarbons for gasoline and jet fuel. We are going to generate our own renewable gas on-site and generate electricity and hydrogen. We plan to be “off the grid," Gruber says. "When we talk about it that way, it changes the way people think about the process and what can be done."
He adds that the starches in corn aren't that digestible for cattle, causing those methane-creating burps that cows have gained notoriety for. Yet this process, he says, captures all the carbohydrates, so the feed coming from the plant is mostly protein. "That makes a difference in the methane cycle, too; we can reduce it," he says. “With our manure digestion projects to make renewable natural gas, we can do something about methane from the other end of a cow, too.”
Electricity is required to make the products in the Lake Preston plant. But the design takes that into consideration. The water treatment plant will be designed as an anaerobic digester to capture methane to use for the boilers, and to run a combined heat and power unit that generates electricity.
Gevo plans to build a wind power project to supply additional electricity to the plant. To drive carbon scores even lower, Gevo plans to set up the capability to use renewable natural gas from its manure digestion project that is likewise soon to be built. In addition to solving greenhouse gas emissions attributed to cows, Gevo’s manure digestion project would capture nitrogen, phosphorus and potassium to put back on the fields, reducing the need for chemical inputs at the farm level. The aim is to maximize that Gruber calls the circular economy.
Net-Zero 1 output
The new plant aims to produce 45 million gallons of net-zero, energy-dense liquid fuel. It will also produce about 360 million pounds of high-quality protein feed to go back to livestock producers in the area. Gruber says he's already got take-or-pay contracts in place for the facility, booking its full output when the plant goes live.
"We are in the renewable energy business. We capture renewable energy and transform it into hydrocarbon liquids such as gasoline and jet fuel. Then when burned, that can have net-zero emissions. We are in the business of counting carbons and getting paid for de-fossilization in the transportation sector,” Gruber says.
You can learn more at gevo.com.
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