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.
Figure 1. Two R1270 units, each with 260-kW cooling capacity, chill brine at a plant in Orlando. Source: Versatile Refrigeration Inc.
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.
McCord expects the use of HFO-1234yf to grow from three million vehicles at the end of 2014 to seven million by the end of 2015.
DuPont is selling the new refrigerant as Opteon YF, to both automakers and the service industry in the U.S. and Europe. Its manufacturing sites in China and Japan announced capacity expansions last October; the company says further investments could be made if demand justifies them.
“The industry is moving decidedly toward HFO-1234yf because it offers a range of advantages, including cooling power, energy efficiency, safety, materials compatibility, sustainability and total systems cost effectiveness,” adds McCord.
She downplays the potential of carbon dioxide as an alternative in automobile air conditioning systems. “While carbon dioxide also was proposed as a low GWP automotive refrigerant, it has been 25 years since the first patent was issued for this technology, yet all indications from the automotive industry are that commercialization of this technology would occur well into the future. Carbon dioxide has low energy efficiency in warm climates, potential for passenger asphyxiation in the event of leaks, and requires a high pressure system that adds weight and size, presenting problems for small car designs and, reportedly, greatly increasing the costs of automotive air conditioning.”
In tests, the Japanese Automotive Manufacturer’s Association, Tokyo, has determined that under various climate and use conditions, Opteon YF has the potential to reduce the total lifecycle climate potential (LCCP), or contribution to climate change, by 20–30% versus R134a or carbon dioxide systems, assuming global adoption.
Regulation And Technology Issues
Regulation may the main driver for the move to natural refrigerants, but how the rules are applied varies both within and between jurisdictions. In Canada and the U.S., for example, various codes including the Uniform Mechanical Code (UMC), California Mechanical Code, International Mechanical Code (IMC) and the Canadian Mechanical Refrigeration Code come into play.
“Their intent is very similar — safety and proper installation practices — but each code is set up slightly differently for the jurisdiction it is meant to cover,” notes Eric MacGregor, general manager, Versatile Refrigeration Inc.
He cites as an example the recent installation of a hydrocarbon chiller at a U.S. company using the IMC regulations. Another company just ten miles away but in a different county was subject to the UMC regulations (Figure 1).
Then there are the ongoing conversations with the U.S. EPA about what constitutes an acceptable industrial use: “Although the EPA has set out a number of approved end uses, each new use of R290, R600a, R1150, R1270, etc. has to be approved as an acceptable substitute under the Significant New Alternatives Policy (SNAP) program,” he notes. Such approvals can be limited to very specific applications, for example centrifugal chillers, absorption systems, chillers for vapor compression with a secondary loop, vapor compression or absorption systems, and vapor compression with a secondary loop.
Moreover, integrating new equipment into existing facilities can raise significant technical issues. Hydrocarbon chillers and other refrigerant-carrying components can pose an extra challenge if they are in certain hazardous areas. For example, a Class 1, Division 2 area normally doesn’t have flammable vapors present — but they could arise due to a leak or catastrophic event associated with a chiller. So both the equipment comprising the chiller and the equipment around the chiller must be intrinsically safe. You also must consider where the refrigerant goes in the event of a release.
“Some regulations require a flare stack to handle possible releases, although this varies by jurisdiction, and we have not seen it required in installations outside the U.S. The new chiller might also face space issues; they are generally smaller than other refrigeration systems but may have larger clearance requirements. Also with the hydrocarbon they may need to be located to a new area due to possible ignition sources,” he warns.
Another challenge is training. You need personnel who are fully trained to work with the hazardous new refrigerants — requiring in many cases quite a new skillset, he notes.
Companies also must grapple with coming up with an appropriate strategy for switching to natural refrigeration technology. This can range from retiring existing equipment as soon as possible to running the units until the end of their useful lives before replacing them. MacGregor cautions that, whatever the investment strategy being pursued, calculations must include the costs associated with leak detection, shutdown procedures and new alarms.
MacGregor also notes that with few manufacturers of equipment that use natural refrigerant technology, choice is limited and costs relatively high. This will change as more companies enter the market and competition increases, he believes.
“However, what really impresses potential customers are the figures: a hydrocarbon refrigerant is typically 20% more efficient than a synthetic, so there’s a big energy saving to start with. Also, you only need about half the weight of hydrocarbon versus synthetic, depending on the application and the synthetic in question. These are very big selling points,” he emphasizes.
“My concerns with all refrigerants are operational suitability and efficiency, as well as refrigerant lifecycle environmental impact from production to destruction. I would like to see more options on the market that offer good efficiency and low environmental impact. Those two attributes have been at odds with each other in the past,” he adds.
The option currently favored by Versatile Refrigeration for its refrigeration systems is an R1270, refined propylene.
“We still have to push for more efficiencies and societal acceptance is going to be very important; in the end it’s a question of environmental stewardship,” MacGregor concludes.