Integration of Life Cycle assessment and population balance model for assessing environmental impacts of product population in a social scale case studies for the global warming potential of air conditioners in Japan |
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Authors: | Kazuhiko?Yokota Email author" target="_blank">Yasunari?MatsunoEmail author Masaru?Yamashita Yoshihiro?Adachi |
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Institution: | (1) Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, 113-8656 Bunkyo-ku, Tokyo, Japan |
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Abstract: | Scope In this study, a dynamic model was built in which LCA and PBM were integrated to quantitatively assess the total environmental
impacts induced by the product population in a society over time. Specifically, a determination was carried out concerning
how Japan’s air conditioner population is used (lifetime distribution, number of units, etc.) and an assessment was made concerning
the Global Warming Potential (GWP) associated with the air conditioner population.
Methods The proposed dynamic model was applied to air conditioners for analyzing the total GWP caused by the air conditioner population
in Japan from 1990 to 2010. To create a trend forecast model for future environmental load, scenarios for air conditioner
production up to 2010 were formulated and the total GWP from the air conditioner population was predicted. Conducted also
were sensitivity analyses whose parameters were air conditioner performance, lifetime and the rate of refrigerant recovery
when retired units are processed.
Results and Discussion Applying the PBM to the air conditioner population in 2000, it was found that 81.5 million units consumed 5.94 x 10p10 kWh in that year, which was a 6.1 % increase in the total annual power consumption in 1990. In both a stationary scenario
and a steady growth (1.5% annual increase), it was found that the total GWP would be 27.7% higher than in 1990 under the stationary
scenario and 37.8% higher under the steady growth scenario. The improvements in air conditioner performance will have a small
effect on reducing the total GWP from that population. Furthermore, in connection with the average lifetime, it was found
that the GWP, due to refrigerant releases when units are disposed of, would be relatively large in 2000 and the following
years.
Conclusions Thus, shorter product lifetimes will spur a replacement of air conditioners with new units, a situation that will only lead
to the reduction of GWP if the recovery rate of refrigerant is to be achieved to more than 50% under the stationary scenario.
Recommendations and Outlook To meet COP3 targets for Japan in 2010 (i.e. to reach the same level as in 1990 for household appliances), our study shows
that it will be vital to raise the refrigerant recovery rate. If the number of air conditioners in use remains unchanged,
recovery would have to be 45.7%, but under the steady growth scenario it would have to be at least 60.4%. Therefore, it will
be difficult to meet COP3 targets unless the refrigerant recovery rate is strongly increased. This method is applicable to
assess not only the GWP of air conditioners, but also other environmental impacts caused by a variety of product populations,
which will be quite effective for setting targets of products’ performance, policymaking, etc. |
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Keywords: | Air conditioner COP3 target global warming potential (GWP) life cycle assessment (LCA) lifetime shift performance improvement population balance model (PBM) scenario analysis sensitivity analysis |
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