Status of Carbon Dioxide Availability for Drinking Water Treatment
Last Updated: 7/30/2024
Overview of Carbon Dioxide Production in the U.S.
Carbon dioxide (CO2) is produced from naturally occurring CO2 reservoirs, as a byproduct from the energy and industrial production processes (e.g., ammonia production, fossil fuel combustion, ethanol production), and as a byproduct from the production of crude oil and natural gas. Domestic production of CO2 is largely supplied by recovery of CO2 as a byproduct of chemical manufacturing, primarily from ethanol, ammonia, and hydrogen manufacturing facilities. Fermentation from ethanol plants is the largest single source of CO2 for the U.S. market and has historically produced more than half of the CO2 sold in the domestic market. CO2 is processed to a liquefied gas after distillation of the crude gas using a cryogenic process, often at facilities located near CO2 sources.
Learn more about CO2 production and additional supply chain information in EPA’s Carbon Dioxide Supply Chain Profile.
Issues Impacting Carbon Dioxide Availability
The source of CO2 varies regionally, depending on the predominant industry producing CO2 as a byproduct. This can lead to regional vulnerabilities in supply. Where CO2 production is heavily reliant on the production of ethanol or ammonia, there is planned downtime at the ethanol and ammonia plants in the fall season, which can temporarily impact the availability of CO2. Where CO2 production is a byproduct of natural gas production, availability of CO2 is tied to fluctuations in natural gas production. In recent years, there have been recurring CO2 supply issues in the southeast U.S. (particularly in Florida).
Grades of Carbon Dioxide Approved for Use in Drinking Water Treatment
Most states in the U.S. with primacy for implementing drinking water regulations require that chemicals used during water treatment are certified under NSF/ANSI/CAN Standard 60. This requirement can extend to CO2. However, water treatment applications account for approximately 3% of the total consumption of purified CO2 in the U.S. Given the limited market for water treatment applications, NSF-60 certified CO2 products are offered by a relatively small number of companies. Utilities can use EPA’s NSF-60 Certified CO2 Suppliers or NSF’s Search for NSF Certified Drinking Water Treatment Chemicals webpage to identify these suppliers in their region.
Some state primacy agencies also allow for the use of alternate grades of CO2, such as food or beverage grade product, which accounts for approximately 70% of the CO2 in the domestic market. Utilities can contact their state primacy agency to discuss if, and under what conditions, alternate grades of CO2 may be used. The ability to use food or beverage grades of CO2 can give utilities access to additional suppliers and to much more product in the domestic market. Utilities can use EPA’s Food Grade CO2 Suppliers and Producers to identify suppliers and producers in their region.
Approaches for Preparing for Potential Supply Disruptions
The following are approaches that water utilities can take to prepare for potential CO2 supply disruptions:
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Establish a contract with your primary supplier. If your utility has not established a contract to procure CO2, consider doing so. Establishing contracts with suppliers can put your utility in the best possible position to manage a supply disruption, as many chemical suppliers respond to disruptions by prioritizing allocation of product first to critical customers (including water/wastewater utilities), then other customers that have a contract, and finally other organizations that do not have a contract and request product (if there is sufficient product to do so). Smaller utilities that use small quantities of CO2 can form consortiums or establish cooperative contracts to negotiate contracts as a group.
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Contact alternate suppliers. Identify alternate suppliers that could provide CO2 for your utility. Contact the sales representatives for your region to discuss the possibility of making special requests for product in the event of a supply disruption and/or establishing a backup contract for CO2. Use EPA’s NSF-60 Certified CO2 Suppliers and Food Grade CO2 Suppliers and Producers to identify alternate suppliers in your region.
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Identify mutual aid and assistance contacts. Join your state’s Water and Wastewater Agency Response Network (WARN) and other mutual aid networks, as well as identify nearby water utilities that may be able to assist in the event of a future supply disruption of CO2.
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Consult your state primacy agency. Contact your state primacy agency to discuss if, and under what conditions, alternate grades of CO2 may be used for water treatment.