High efficiency ac could save 25Gt of CO229th July 2015
A draft report presented at last week’s 36th Montreal Protocol OEWG meeting in Paris suggested that such an action would provide a substantial part of the mitigation needed to keep the planet from warming more than 2°C above pre-industrial levels – a figure considered by many as the upper temperature limit for preventing potentially irreversible and catastrophic climate change impacts.
The report by researchers at California’s Lawrence Berkeley National Laboratory (LBNL) maintains that improving the efficiency of air conditioners and switching to lower GWP refrigerants could avoid an estimated 25 billion tonnes of CO2 emissions in 2030, 32.5 billion tonnes in 2040, and 40 billion tonnes in 2050. Savings in peak demand could be equal to 500-1200GW of electricity.
These estimates show the emissions reduction potential that could be captured over the lifetime of the ACs for the global stock in 2030. The report authors point out that the cumulative emissions reduction would be much higher than these estimates and would accrue even higher total benefits the earlier the policy is enacted.
The draft report by Nihar Shah, Max Wei, Virginie Letschert, and Amol Phadke , entitled Benefits of Leapfrogging to Super-efficiency and Low Global Warming Potential Refrigerants in Air Conditioning, was presented as parties to the Montreal Protocol discussed potential controls of HFCs.
“The proposed HFC amendment would avoid the equivalent of another 100 billion tonnes of CO2 by 2050, and perhaps much more, and would avoid more than 0.5°C of warming by end of century,” commented Durwood Zaelke, president of the Institute for Governance & Sustainable Development.
“Leapfrogging over HFCs into climate-friendly alternatives during the ongoing phaseout of HCFCs under the Montreal Protocol would add an additional 39 to 64 billion tonnes of CO2 equivalent; this could bring the total mitigation up to 250 to 300 billion tonnes CO2-equivalent by 2050 from a dual strategy to phase down HFCs while improving air conditioning efficiency,” Zaelke added.
“Past phase outs of refrigerants under the Montreal Protocol have catalysed improvements in appliance energy efficiency on the order of 30 to 60%. Parallel efforts to set efficiency standards and to ban imports of inferior air conditioners could ensure that efficiency was improved even faster,” Zaelke said.
Discussing the report, Dr Nihar Shah, the lead author of the report, said: “Our calculations take into account that there will be some rebound effect from efficiency improvements, as some users will use their air conditioners more when they are cheaper to operate. Even with this, the climate and cost benefits are substantial.”
The lower GWP refrigerants considered included R32, R290 and some HFO blends as offering offering significant emissions abatement potential. Other HFO blends, the report observes, offer reduction in emissions due to lower GWP but increase indirect emissions compared to the baseline R410A due to lower cooling capacity, lower efficiency or both.
The report points out that the systems tested under the AHRI’s Alternative Refrigerants Evaluation Programme (AREP) were not specifically designed and optimised for the low-GWP refrigerants; systems optimised for the refrigerants, it says, could show greater efficiency.