More recent interest in developing alternative refrigeration and air conditioning technologies is motivated by international efforts to stem ozone depletion and global warming. The majority of the 60 million residential air conditioners in the U.S. use hydrochlorofluorocarbon 22 (HCFC-22 or R-22) as the "working fluid" or refrigerant gas. Although R-22 will be available for the near term, recent amendments to the Montreal Protocol have accelerated the phase out of R-22 and other HCFC refrigerants.
On occasion of the 20th anniversary of the Montreal Protocol, all 191 member parties unanimously decided for an earlier ban of HCFCs not only to reduce ozone depletion but also as a means to fight global warming. In the last decade, the Montreal Protocol has supported the targets of the Kyoto Protocol that seeks to reduce global warming refrigerants, such as HFCs.
In a recent report by the Environmental Investigation Agency (EIA) titled "Turning Up the Heat", an analysis of HCFCs and HFCs used in refrigeration and A/C applications concludes that these chemicals are up to 10,000 times worse for the climate than carbon dioxide, and their emissions could be expected to add two to three times more greenhouse gases to the atmosphere than the Kyoto Protocol is required to reduce. "As it stands the global warming impact of world HCFCs and HFCs emissions will rival the total greenhouse gas emissions of the entire European Union within ten years," said Alexander von Bismarck, campaign director for EIA's Washington, DC office.
Current amendments to the Montreal Protocol establish a production and consumption cap for HCFC-22 at 1/1/2009 levels with a complete ban on production and consumption by 1/1/2020.
In response to these established deadlines the HVAC industry has put substantial development resources into qualifying other technologies - including hydrocarbon and carbon-dioxide based systems. Broadly speaking, these technologies have been adapted to the applications and equipment being adversely affected; however, equipment costs, operating safety, and durability are expected trade offs.
The timing and opportunity to develop and commercialize thermoacoustic based systems, given the relative obscurity of thermoacoustic technology, its benign environmental impact, mechanical simplicity, extended maintenance-free operation and potential for consumer driven technological adoption is now!