Carbon dioxide (CO2) technology is important in many commercial and industrial applications. For example, leading companies including Western Digital, Pentel, Gillette-PaperMate, Raytheon and Seagate have implemented CO2-based cleaning technology because it has improved the productivity, worker safety and profitability of their precision cleaning operations. These same businesses have implemented CO2 technology as a strategy for complying with stringent environmental regulations.
CO2 is produced and captured as a by-product of natural and industrial processes (aka recycled CO2) and is a valuable resource for a number of commercial and industrial processes. Recycled CO2 is a net benefit in terms of energy conservation, pollution reduction and other important societal benefits. No additional quantities of CO2 are added to the atmosphere by using this valuable waste byproduct. Users of recycled CO2 are not considered generators of CO2. This is the position of the United States Environmental Protection Agency (EPA).1
Arguably, the most important reason for using recycled CO2 is that it efficiently replaces the valuable function provided by industrial processing agents such as de-ionized water, solvents, soaps, lubricants and coolants. Recycled CO2 eliminates the negative environmental and energy consequences associated with manufacturing, packaging, transporting, treating, recycling or disposing of conventional processing agents. Replacing conventional manufacturing agents with recycled CO2 conserves natural and human resources — water, oil, energy, time, capital and labor. Producing, transporting and consuming less processing agents eliminates the production of associated environmental pollution and waste by-products such as solid wastes, liquid wastes, Hazardous Air Pollutants (HAPs), Volatile Organic Compounds (VOCs) and greenhouse gases (GHGs).
Moreover, utilization of recycled CO2 delivers additional societal benefits such as safer working environments, cleaner air, cleaner products, longer lasting machines and tools, higher production yields, increased productivity and improved global competitiveness.
A RECYCLABLE BYPRODUCT
The CO2 used in industrial applications such as cleaning, machining and thermal control, among many others, is commercially obtained as a gaseous by-product from ammonia and petrochemical plants as well as natural CO2 gas wells.
CO2 is an integral part of the basic life cycle in nature. Humans and animals give off CO2 that is used by plants to help them grow. Plants, in turn, release oxygen, upon which we depend for survival. In fact, it's the same CO2 that you are producing and exhaling while reading this article, about 2 pounds of it each day! CO2 is captured as a gas, compressed to a liquid and supplied commercially in steel cylinders, mini-bulk tanks, and bulk storage tanks. This is the starting compound from which important solid, liquid and supercritical CO2 process agents are produced.
CLEAN AND VERSATILE
Carbon dioxide technology is a cost- and performance-effective replacement for a variety of environmentally undesirable industrial agents such as HCFCs, VOCs, methylene chloride, n-propyl bromide (nPB) and perchloroethylene. CO2 cleaning technology has demonstrated enhanced product yields, process performance and manufacturing productivity, while improving environmental quality in the workplace.
CO2 offers environmental and cost benefits because it is non-toxic, non-hazardous, non-corrosive and non-flammable; it offers a competitive cost-of-ownership; there are no waste by-products and no drying; and it will not run out of supply since it is an abundant byproduct of numerous industrial and natural processes.
Unlike any other single manufacturing agent, CO2 can be used as an immersion cleaning agent, spray cleaning agent, surface treatment agent, coolant, lubricant and extraction solvent. Moreover, CO2 technology can accomplish manufacturing tasks in ways previously not possible, such as being integrated directly into production tools or combined without significant constraints with most manufacturing operations. Entirely new manufacturing tools and processes can be produced as a result. This unique capability can be exploited in many industrial markets and applications, including general or precision cleaning, biomedical treatment, textile processing, materials extraction, surface modification, precision machining and thermal control.
A CLEANER, SAFER CHEMISTRY
Organic compounds such as n-propyl bromide, perchloroethylene, trichloroethylene, fluorocarbons and many other solvents, lubricants and surfactants are derived from our energy supplies. These compounds may be used as industrial cleaning, machining and refrigeration agents. The production of these chemicals produces millions of pounds of greenhouse gases as well as many other air polluting by-products each year. Moreover, significant electrical energy is consumed to produce these compounds, treat waste by-products and to transport these compounds.
Energy production alone produces the most significant amount of CO2 gas as a byproduct (see chart). Using recycled CO2 as a substitute manufacturing agent is a means for reducing the energy and resource wastes associated with industrial chemical production. This conserves our vital coal, oil, natural gas and bio-energy resources and prevents the creation of additional solid wastes, air and water pollution.
Compared to common organic cleaning solvents, recycled CO2 costs less, does not deplete the ozone layer, is worker-friendly and is not considered a volatile organic compound.2 CO2 offers a combination of cost-of-ownership and environmental, health and safety benefits not found with any of the common cleaning solvent alternatives.
Recycled CO2 also offers several worker safety and health benefits. These include the absence of hazardous lung inhalation and infectious dermal contact issues. CO2 is not considered a carcinogenic or mutagenic compound. Finally, CO2 eliminates fire hazards and equipment corrosion issues associated with certain types of manufacturing agents.
GREENHOUSE GAS REGULATIONS
Greenhouse gas emissions reporting legislation, proposed under USEPA 40 CFR Parts 86, 87, 89 et al, is intended for “generators” of CO2 and other GHGs3. A user of recycled CO2 is not considered a generator of CO2. Recycled CO2 delivered by gas suppliers to companies for use in commercial and industrial manufacturing processes already is accounted for in the EPA national GHG emissions inventory reporting requirements. Examples of significant sources of CO2 generated as a byproduct of industrial processes and cited in proposed GHG reporting requirements include, among many others, electrical power generation and usage; chemical generation and usage; and transportation.
The use of CO2 technology as a chemical substitute lowers electrical power usage, reduces manufacturing wastes, increases manufacturing productivity and decreases the need for chemicals such as lubricants and solvents. A reduction of manufacturing wastes or elimination of production chemical inputs of any kind decreases industrial CO2 generation.
For example, less CO2 is produced if less electricity is consumed; if less oil is refined, transported and consumed; if less cleaning solvents are produced, transported and consumed; if more products can be manufactured for the same energy inputs; if fewer chemical waste streams are treated, recycled or hauled away; if less rework is performed and scrap produced; and if products don't have to be cleaned or dried.
Therefore, using recycled CO2 technology as a process and chemical substitute offsets CO2 gas production and emission from both the industrial supply and consumption sides of the equation.
PART OF THE SOLUTION
Replacing conventional manufacturing agents used in industrial processes such as cleaning and machining with recycled CO2 produces no net increase in pollution. In fact, recycled CO2 is an opportunity to reduce the production and use of many manufacturing agents derived from our critical energy and water resources. This lowers energy costs and reduces the production of significant quantities of solid wastes, spent solvents, waste oils, wastewater and air pollution.
CO2 technology is safer for people and offers a competitive cost-of-ownership when used in industrial processes such as precision cleaning, machining and dry cleaning textiles. The bottom line is that CO2 technology is an important part of the global energy savings and pollution reduction solution.
David Jackson has worked as both a corporate environmental manager and an independent environmental consultant. He has developed numerous CO2-based cleaning, machining and thermal control products. He can be reached at [email protected] or 661-775-5964.
Letter from United States Environmental Protection Agency (USEPA) to Deflex Corporation, November 25, 1997, Subject: Carbon Dioxide Emissions.
Montreal Protocol on Substances that Deplete the Ozone Layer, United Nations Environmental Programme (UNEP) Report, Technology and Economic Assessment Panel (TEAP), April 2001
USEPA, 40 CFR Parts 86, 87, 89 et al, Mandatory Reporting of Greenhouse Gases, Proposed Rule, April 10, 2009