Regulatory pressures are forcing the phase-out of many widely used refrigeration gases and their replacement with more environmentally friendly alternatives. For example, the U.S. Environmental Protection Agency (EPA) ruled in October that domestic production of R22 (chlorodifluoromethane) should end within five years.
So the industry is turning to alternatives such as ammonia, carbon dioxide and a range of hydrocarbons with low ozone depletion potential (ODP) and low global warming potential (GWP). Such hydrocarbons include: R1270 (refrigerant-grade propylene), R290 (propane), R600 (butane) and R600a (isobutene), together with raft of blends that emulate the performance of existing refrigerants while also providing efficient and environmentally friendly replacements for them.
This offers chemical companies a two-fold opportunity: to improve their own processes by switching to these refrigerants, and to manufacture them to meet the demand. Roche, Basel, Switzerland; and DuPont, Wilmington, Del., are at the forefront of these efforts. However, suppliers such as Versatile Refrigeration, Chemainus, B.C., caution that both the legislation and the technology needed to deal with new refrigerants still are evolving.
One of the most proactive chemical companies when it comes to replacing old-style refrigeration gases is Roche. The company’s Group Directive K6 covers substances affecting the ozone layer and climate and focuses on halons, CFCs, HCFCs, HBFCs, HFCs and PFCs. K6 calls for removal of 90% of these substances from legacy company operations by the end of 2015. Acquisitions will be subject to “appropriate new timeframes.”
Roche eventually will ban all these materials from aerosol products manufactured by the company or its affiliates, and from foam products used both for packaging material and new thermal insulation applications. (Existing insulation uses can remain in place until the end of their service lives.) Similarly, Roche will prohibit the gases in production processes; however, it still will permit small-scale laboratory use in certain test methods.
The company is turning to a range of natural refrigerants to help meet these targets — for example, ammonia for air conditioning, carbon dioxide for cold room chilling, and hydrocarbons such as propane, isobutane and ethylene for lyophilization — a freeze-drying process designed to preserve material and make it easier to transport.
As part of this initiative, Roche has designed and installed energy-efficient and environmentally friendly refrigeration systems at sites in the U.S, Ireland and Germany. These use only natural refrigerants, mainly ammonia.
Its Indianapolis site now has a centralized 16,000-m2 chiller plant fitted with seven ammonia chillers to cool water that then is pumped through a pipe system to individual buildings on site to help keep workers cool. Roche notes that this project required some extra safety features such as ammonia sniffers. As well as being environmentally friendlier than the technology it replaced, the new chiller system is twice as energy efficient, says the company.
A similar project has been undertaken at a site in Ireland, with partial funding from the Sustainable Energy Authority Ireland, Dublin, whose role is to advance the use of sustainable technologies within the country. Here, an almost-two-fold increase in energy efficiency has cut power demand by 925 MWh/y — a savings of 575 t/y of carbon dioxide emissions.
Each ammonia refrigeration system design in Ireland also will incorporate an open flash economizer vessel. Such a vessel allows a considerable portion of the cooling to be carried out at a much higher temperature, approximately -8°C, instead of -22°C or -29°C, saving substantial energy, says the company.
In Germany, a logistics center is using a mixture of natural refrigerants including ammonia, propane and carbon dioxide to provide freezing down to -70°C.
Meanwhile, DuPont is urging customers to make R22 an asset and offers advice on recovering and reclaiming it, repairing leaks and maintaining equipment performance. The company also offers its own alternative — Isceon MO99 — as a retrofit to extend the useful life of the equipment.
DuPont also foresees a good future for its new HFO-1234yf refrigerant for automotive air conditioning. A hydrofluoro olefin (HFO), the gas can replace R134a now used as a refrigerant in automobile air conditioning systems. It has a GWP rating 335 times lower than that of R134a.
HFO-1234yf was developed to meet the European Mobile Air Conditioning (MAC) directive that went into effect in 2011 and requires all new car platforms for sale in Europe to use a refrigerant in their air conditioning systems with a GWP below 150. The U.S. EPA also has issued a proposal that would limit the use of R134a in automotive air conditioning.
“HFO-1234yf has a 99.9% lower GWP than the refrigerant it was designed to replace, and meets a range of critical performance, sustainability and safety needs. Other low-GWP refrigerants are available for use in complying with the MAC Directive, but most automakers have concluded that HFO-1234yf is the best option. Most of the world’s major automakers have already started their commercial transition to HFO-1234yf, and all but one are working to adopt HFO-1234yf,” says Kathryn K. McCord, global business director, DuPont Fluorochemicals.