The Ethanol Industry’s Commercial Capture

CO2 from corn ethanol plants is a great candidate for capture and sequestration because it is so clean. That also makes it a versatile and critical product for myriad commercial and industrial uses.
By Katie Schroeder | June 06, 2022

New and improving methods of reducing the carbon intensity (CI) scores of corn ethanol are enabling producers to tap into markets that place a premium on low-carbon biofuel. Carbon dioxide pipelines, which seek to aggregate CO2 from Midwest ethanol plants for permanent geologic sequestration—and cut CI scores in half—is an attractive option for ethanol plants that don’t already capture CO2 for commercial use. For the those that do, the jump to sequestration may be complicated by their already vital role as merchant CO2 suppliers.

Sam Rushing, president of consulting firm Advanced Cyrogenics and frequent contributor to Ethanol Producer Magazine, is an expert on the myriad commercial uses for CO2. He explains that 40 to 45 percent of the CO2 on the U.S. market comes from ethanol production. Rushing’s company helps producers find ways to “monetize what would otherwise be vented to the atmosphere” or, in the near future, sequestered. He says Advanced Cryogenics helps corn ethanol producers find the right use for their CO2, whether that be for captive or merchant use. “It’s all about sustainability as well, trying to come up with programs and sources and destinations that would be sustainable throughout time,” Rushing says.

Ethanol giant POET actively captures and sells ultra-high purity CO2 to the beverage industry for carbonated drinks, the food processing industry for refrigeration, municipalities for water treatment, and more, under the POET Pure brand, according to Doug Berven, POET’s vice president of corporate affairs. “It’s the right thing to do for the environment, to capture it and utilize it wherever we can, rather than venting it,” Berven says. As of mid-April, POET captures CO2 at roughly a dozen of its bioprocessing plants, more than a third of its fleet. 

While CO2 is not exclusively captured by the ethanol industry, ethanol producers have a unique selling point, in that CO2 captured from the process is renewable whether it is sequestered or not. Berven explains that the CO2 produced at POET has 65 to 85 percent less greenhouse gas emissions compared to competitors capturing CO2 from oil wells or ammonia manufacturing. “Any time we are sequestering or utilizing carbon we are reducing [CO2 in the atmosphere]. We’re not adding to [the atmosphere] like our competitors are,” Berven says. “That’s a really important aspect to understand.”

Utilizing CO2: Technology and Challenges
The technology for capturing and liquifying CO2 in an “over-the-fence” operation at an ethanol plant is not overly complicated, Rushing explains. “We are capturing CO2 off the fermentation process and then we condense it, and can sell it as a liquid,” he says. “What it really amounts to is, we have a skid that takes that CO2, scrubs it and then utilizes it, puts it in a form that is easy to ship either via truck mostly, or rail.”

The transportation element is key and can be a problem for anyone looking to pursue merchant CO2. Rushing explains that the CO2 must be compressed into a liquid in order to be transported and stored, since it would have too much volume for easy containment in gas form. “Thirty percent of the transportation of the commodity is by rail and 70 percent by truck, so it’s all about transportation, it’s the bottom line, it really is,” Rushing says.

POET is currently considering a variety of new technologies related to CO2 capture, utilization and sequestration, Berven says. “We are looking at all the options, everything that CO2 might be used for, whether that’s carbon capture and storage … further downstream technology or just being able to capture it and use it as a wholesale feedstock,” he explains.

POET is also continuously evaluating the markets, logistics and political landscape around CO2 utilization. “Various hurdles or just general business challenges,” Berven says. “I think we’ll be working out a lot of those challenges in the near future.”

He continues, describing the sensitive nature of the domestic CO2 market: “CO2 is a smaller marketplace, obviously, than the bioethanol or feed products we produce, but there is significant value there for a lot of different markets.”


Uses for Merchant CO2
The merchant CO2 sector typically produces food- or beverage-grade product as that large market segment tends to dictate product specs. “Many producers will make their CO2 beverage grade because the quality has higher requirements,” Rushing says. “It’s like the benchmark of good quality, so virtually all the merchant plants are making beverage grade CO2, even though the product might go to food and beverage.” He explains that about 70 percent of the CO2 in the United States goes to the food and beverage industry, 40 to 45 percent of which goes to the food industry where it is used for freezing and chilling, among other uses. Liquified CO2 is very cold and makes a great refrigerant. The beverage side of the CO2 market was holding steady, making up around 15 to 20 percent of the market as consumers had been trending toward buying more uncarbonated sports drinks and bottled water. However, Rushing explains, with the explosion of seltzer drinks and specialty beers, there is a growing need for CO2 within the beverage industry.

The other 30 percent of the CO2 merchant market is used for industrial purposes, everything from agriculture to the metal trade. CO2 is used for growth enhancement for high-quality crops like cannabis and tomatoes in an enclosed greenhouse environment. “Plants utilize CO2 for photosynthesis and exhale oxygen, so it’s essentially a very good application that’s very common in some markets,” Rushing says. The increased use of CBD has also brought another use for CO2, as it is used to extract CBD oil from cannabis and may be preferred over some other hydrocarbons like propane or butane since it doesn’t have any extra byproducts. CO2 is also used in metallurgy to stir molten metal, a gas shield for welding, hardening sand cores in the foundry industry along with many other applications. CO2 is also used for high-pressure blasting with small rice-sized dry ice pel­lets.
 
“Under high pressure, they blast clean instead of using sand and solvents, which essentially means that little-bitty grains of dry ice under pressure—like 1,600 pounds of pressure—are used in lieu of solvents, sand and stuff like that,” Rushing explains. “You won’t end up with a big pile of sand or a whole bunch of solvents on the ground since [dry ice] dissipates directly from a solid to a gas.”

All of POET’s carbon dioxide product is beverage grade, and the company is in the process of looking at technologies to further enhance its CO2 business. POET currently sells CO2 directly to its customers but is looking to expand its reach. “We’re looking at all different types and forms of technologies and partners to advance the use of CO2 for sure,” Berven says.

CO2 that is sequestered may earn producer tax credits, but CO2 captured for merchant use does not earn tax credits since it generally ends up in the atmosphere after its use as a product, Rushing explains. Although merchant CO2 products generally dissipate into the air after commercial use, Rushing says there are technologies being developed to potentially recycle CO2 for additional uses, in refrigerant systems for example.

Captive CO2 and Sequestration
Captive uses for CO2 include enhanced oil recovery as well as sequestration. “If you turn it into a useful fuel or chemical or something like that, that’s one form of sequestration,” Rushing says. “Otherwise, it would be something like downhole into the right geologic formation. Sometimes it’s for enhanced oil recovery—which is [viable once again] due to the cost of oil these days.” Much of the value proposition for sequestering carbon dioxide currently comes from federal tax credits from Section 45Q, which Rushing says yield producers $20 to $50 per sequestered ton of CO2. Plus, Rushing says, credits given to biofuels that, because of future sequestration, attain a low CI score (under California’s Low Carbon Fuel Standard) further amplify the financial allure of sequestration. 

Although he sees value in merchant CO2, Rushing sees sequestration as the end goal. “CCS, to me, is the future,” he says. “[The planet] is drowning in CO2  … and we’re talking about sustainability here. That’s one thing that really needs to be dealt with—really, really does.” But Rushing feels that the tax credits in place need to reflect some of the other ways producers might take CO2 out of the atmosphere besides putting it in the ground, such as utilizing it to enhance plant growth in an enclosed greenhouse. Hopefully, he says, incentives will be extended to certain types of utilization in the merchant industry. “I’d like to believe that some of this will evolve,” he says. “To me, the cleanest thing in the world, if you think about it, would be plant utilization,” he says. “They suck [CO2] up and give us, you know, something more, whether it be a tomato or something else. They yield oxygen, which we need to breathe, and it’s the same for the forest and everything else … totally sustainable.”

Berven agrees that tax credits can help implement renewable products that might otherwise have a difficult time breaking through in a market with established technologies. “Sometimes it does take tax credits or subsidies to help an industry establish itself, [especially] when it comes to climate change and things like that,” Berven says. “I think there is a responsibility in the political realm to help expedite some of these technologies, no doubt about it. But there are other benefits out there as well.”

Ethanol producers have an opportunity to jump into a market which, at the moment, is tight due to Covid-related shortages. “Anybody that is venting the product and not selling it to the industry or [involved with] sequestering it should take a look at all the options,” Rushing says. “Today, it’s more valuable than ever. Prices are high, supplies are very tight—and we’ve even had tight supplies in the Midwest, in the Corn Belt.”

Berven believes that there is potential for growth in the CO2 market. “We can use CO2 for so many things, from drop-in designer fuels, to plastics, organic chemistry … the medical field, fire suppression … I mean there’s a lot of different areas where we can use CO2,” he says. “And I think especially for the bioethanol industry, the market is going to expand.”


Author: Katie Schroeder
Contact: [email protected]