The Case for a Credit

by Steffen Mueller and Sam Rushing (Ethanol Producer Magazine) The role of ethanol-based carbon dioxide is often underappreciated, both as an important source for the nation’s carbon dioxide market and for its carbon-reduction impact. Fermentation CO2 is captured, cleaned and condensed at 49 ethanol plants in the U.S., contributing between 30 and 40 percent of the nation’s total CO2 supply.

Currently, ethanol CO2 is not given a coproduct credit in greenhouse gas (GHG) modeling. The argument is that although the CO2 is captured, it is not being sequesteread and will ultimately be released into the atmosphere. Considering the importance of fermentation CO2 to several industrial and food segments, the life cycle modeling should be transitioning from a waste product to being viewed as a coproduct. And, considering the environmental impact of alternatives, there is an argument to be made that ethanol facilities capturing carbon deserve credit for the difference in emissions between gas cleanup and compression of fermentation CO2 versus alternative CO2 production from dirtier, often fossil, resources.

The importance of the ethanol industry’s fermentation CO2 to the U.S. food supply is significant. Other sources include anhydrous ammonia production at 23 plants, hydrogen sources from 20 refineries, natural geological sources from 19 locations and six miscellaneous sources from other chemical processing facilities. In recent years, the best new CO2 opportunities have almost exclusively been ethanol-based. Food and beverage represent 70 percent of the merchant market for CO2 in most regions. Besides adding carbonation to beverages, the food industry uses CO2 as a refrigerant, accounting for more than 40 percent of CO2 application in many markets. CO2 is also used as a preservative and as a solvent for extraction.

Other industrial uses include a wide range of temperature reduction applications, as a shielding gas for welding and a hardening agent in foundries. CO2 is increasingly being used in closed greenhouses to enhance crop growth, being sequestered in the plants themselves. Another interesting application growing in popularity is the application of CO2 in precast and poured concrete, which enhances the calcium carbonate content in the concrete, thus strengthening the material, and secondly, sequestering the CO2 in the concrete. CO2 is also used in pH reduction of municipal and industrial effluent, often replacing sulfuric acid, resulting in environmentally friendly carbonate and bicarbonate byproducts, rather than harmful sulfates.

Tight Supplies
As a significant source of high-quality CO2, the ethanol industry plays a critically important role, according to executives in the merchant CO2 industry.

But the treatment of ethanol-based CO2 may be changing. In recent years, the International Sustainability and Carbon Certification organization included a coproduct credit for CO2 capture in the certification of Sweden’s Lantmannen Agroetanol. This is because the European Energy Directive provides for a coproduct credit of “emission savings from CO2 capture and replacement ... limited to emissions avoided through the capture of CO2 of which the carbon originates from biomass and which is used to replace fossil-derived CO2 in production of commercial products and services.” The 14-year-old Landtmannen plant produces 230,000 cubic meters (60 million gallons) of ethanol annually from small grains. In its 2013 annual sustainability report, the Swedish cooperative reported its ethanol was achieving a 70 percent GHG reduction compared to petrol. The cooperative was anticipating the CO2 plant completion in 2014 would boost that to 90 percent. In its 2015 annual report, the cooperative says it is achieving a 95 percent GHG reduction with its ethanol, producing some 90,000 tons of CO2 annually. READ MORE