CO2 is all around us, the largest greenhouse gas by volume, and an excess of it leads to climate change. This information is well known and frequently stated. However, there is a useful side of CO2; it is an incredibly versatile agent and chemical used throughout the world’s economies. Global CO2 consumption within the merchant markets is approaching 25 million metric tons annually, 40% of which is consumed in the U.S. The next two largest markets are widely considered to be Japan and Europe. These markets represent very diverse CO2 utilization in the merchant markets, which are highly dedicated to its use, first as a refrigerant, followed by many other applications in metallurgy, and also as a supercritical solvent, cleaning agent and versatile chemical.In developing countries, CO2 has historically been a beverage carbonation agent, along with some usage in the form of cylinder gas for welding and in soda fountains. However, the use of CO2 in a wider range of uses is growing, particularly in places like Kenya, where it is used for grain fumigation, meat refrigeration and much more. There is growing momentum for even greater diversity of use in developing countries.In developed markets such as the U.S. and Canada some 70% of merchant CO2 usage is dedicated to food and beverage processing. Depending on the region, cryogenic freezing, cooling, dry ice pressing for food use and modified atmosphere packaging, or MAP, represent the majority of use within this 70% category; the balance is then dedicated to beverage uses. The remaining 30% of the market is medical and industrial usage.Most of today’s merchant plants produce a beverage-grade product, which is essentially the pinnacle of quality, with the exception of specific medical/USP-grade product. Since beverage-grade CO2 is then safe or ultrasafe for virtually all uses, this is the standard for most liquefaction or purification CO2 plants across industries today.Food and Beverage Usage&nbsp; As the largest usage sector within the merchant markets, food processing relies on the use of CO2 in all physical forms: gas, liquid and solid. In a gaseous form, the product is used in modifying the atmosphere within packaged meat and vegetable products, thus removing the oxygen content. Sometimes, CO2 is used in combination with other gases like nitrogen and argon. In any event, this represents a means of extending the freshness of these food products. The use of CO2 as a liquid product is found in cryogenic freezing and cooling operations, where the prepared food products from portioned meats to dinner entrées, vegetable and specific food products pass through various forms of freezers, most of which are in a tunnel or spiral configuration. Cryogenic freezing seals water within the cellular structures of food products; the process leaves more weight in the products and improves their appearance and shelf life. Then, dry ice is pressed to meet the requirements of the processor, often in a “rice” or pellet configuration. This is used for blending, chopping and shipping meat and other food products. Dry ice makes up 20% of most merchant markets by volume.CO2’s use in beverage is relatively straightforward, being used as carbonation. Demand in this sector was relatively flat for many years. However, over the last few years, specialty drinks, such as seltzers and niche brewers, have precipitated significant growth. Many of the large brewers recover their own CO2 from fermentation, making the use of merchant product mostly periodic. The major soft drink firms have highly influenced the practice of ongoing testing for this sector.Another application of CO2 is its use as atmospheric enrichment for closed greenhouses—particularly for premium crops—as well as for supercritical extraction of essential oils and CBD oil. The commodity is used for grain fumigation in some elevators found in the farming community (rather than alternate agents). These applications are often considered to be more “natural” than a hydrocarbon-based product, such as propane or hexane, used for supercritical extraction; they are also an attractive alternative to chemicals used for fumigation. CO2 represents an extremely versatile agent in the food and beverage industries because of its wide range of uses.Industrial and Medical Applications&nbsp; The industrial uses for CO2 are very diverse, including: metallurgical industry applications, uses as an acid, deflashing rubber and plastic parts in manufacturing, as well as uses as a solvent and a cleaning agent.CO2 has a host of uses in the medical industry as well. For instance, gaseous USP-grade CO2 is used as a respiratory stimulant and in surgical procedures, sometimes to open body cavities while performing specific surgical procedures. It can also be used for removing warts and skin cancers. The major CO2 firms strategically operate specific CO2 plants for the production of a USP-grade product. Manufacturing USP simply requires a diligent record-keeping process.Applications for CO2 in the metallurgical industry are broad, from use as a “stirring agent” of molten metal in mills, to use as a shield gas for welding, to use in the cooling of sand cores in foundries. Using the product for “deflashing” rubber and plastic imperfections during the manufacture of various products is again utilizing the refrigeration value found in CO2 under specific conditions.Application of the product for pH reduction is commonly found in municipal potable and wastewater plants, particularly where lime based softening occurs. Applying CO2 creates carbonic acid, a self-limiting acidic agent, which neutralizes the alkaline properties in many municipal water treatment plants. There are many industrial uses for CO2 as an acid for replacement of sulfuric and hydrochloric acids used in paper mills, large cooling towers, potato chip plants and drywall manufacturing. The use of CO2 for its acidic value is ever-increasing as a safe and clean method of treating alkaline effluent.As mentioned earlier, the use of supercritical agents for extracting essential agents for the food and perfume industries is ever-expanding and now includes extraction of CBD oil from cannabis. Growth of cannabis, as well as higher value vegetables and flowers, often uses gaseous CO2 fed into a closed greenhouse for enhancement of photosynthesis, leading to a significantly improved crop yield.CO2 in the form of rice-sized dry ice is used under pressure for blast cleaning of many surfaces, from electronics to printing presses, industrial equipment, the exterior of buildings and ship hulls. This form of cleaning leaves residue only, after the dry ice sublimates—this is far better than sand or solvent blasting becasue the dry ice essentially disappears after use.The use of CO2 in the oil and gas industry is well known, where ethanol and other source types supply large volumes for enhanced oil recovery; it essentially acts as a solvent, sweeping the wells, releasing oil and gas from geologic cracks and crevices, whereas other methods, such as polymers and water flooding alone can’t achieve the same results. CO2 also reduces the pH and swelling of clay in the process of recovering oil. Prior to the advent of modern hydraulic fracturing, CO2 was once a very significant fracking agent as well. Much of the practice is now hydraulic; however, there are cases where there are a lack of adequate disposal facilities for spent fluids from hydraulic fracturing, creating a need for CO2 fracturing.Other industrial uses include concrete dosing, a practice where both sequestration of CO2 occurs and more calcium carbonate is formed, thus strengthening the concrete. CO2 is used in the production of a host of chemicals and other products—including methanol, urea and even aspirin—where the specificity of production inputs is essential. There are applications, such as improved electrical production via CO2 as a supercritical fluid, replacing steam to drive turbines, which conserves energy in power production. CO2 used for the production of formic acid in a catalytic reactor is one example of CO2 being used as a feedstock chemical agent, or preservative, in applications such as fuel cells.The growth of bioplastics production, which can include CO2 utilization, is another path toward more sustainable products that replace hydrocarbon-based materials. Some types of usage lead to displacement of overall CO2; other types of utilization lead to sequestration. In most cases, there is significant economic value to the CO2 from ethanol and other source types across industries utilizing it. Author: Sam A. Rushing&nbsp;&nbsp; President, Advanced Cryogenics Ltd.&nbsp; rushing@terranova.net&nbsp;&nbsp; 305-852-2597&nbsp; &nbsp;

2024-05-07 - Creative Utilization (Ethanol Producer Magazine)

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Carbon dioxide has many merchant market applications, ranging from the medical industry to agriculture to food and beverage.

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