Download Climate Change Issue greenhouse effect> The earth receives

Climate Change Issue
<The greenhouse effect>
The earth receives energy from the sun in the form of visible light rays, and energy escapes from
the earth in the form of infrared rays. The temperature of the earth is determined by these balance. If
greenhouse gases that absorb infrared rays are accumulated in the atmosphere, less of that energy
escapes into space, causing the earth’s temperature to rise. This phenomenon is known as “the
greenhouse effect”.
<Greenhouse gases>
In terms of quantity, carbon dioxide gas has the greatest impact, but CH4, N2O, HFCs, PFCs and
SF6 which are not present in great volumes still contribute to the greenhouse effect.
<IPCC (Intergovernmental Panel on climate Change ; established by UNEP and WMO)>
Evaluates and reports on scientific knowledge of climate change and its environmental and
societal impact. The panel released predictions for the end of 21st century : temperature increase 1.8
～4.0℃, and 18～59cm rise in sea level vs. average value between 1980～1999 in it’s 4th
assessment report published 2007.
<FCCC (Framework Convention on Climate Change)>
Aim : Stabilize concentration of greenhouse gases in the atmosphere at acceptable level.
Adoption : May 1992 at the UN Conference on Environment and Development in Brazil.
Enforcement : March 1994
Conference of the parties to the convention have been held every years since 1995. At the third
conference (COP Ⅲ) held in December 1997 in Kyoto, a protocol was adopted and was called
“Kyoto protocol”.
<Kyoto Protocol>
Target years : 2008～2012
Base year : 1990 (1995 can also be selected for HFCs. PFCs and SF6)
Level : about 5% reduction, average for all developed countries (6% for Japan, 8% for EU)
Target gases : basket of CO2, CH4, N2O, HFCs, PFCs and SF6
Enforcement : February 2005
Nowadays, the climate change issue becomes significant global environmental issue. Although
HFCs emission is extremely low, HFCs was included in the emission reduction target of Kyoto
Protocol because of their high GWP (global warming potential).
HFCs are used in various applications as refrigerant, blowing agent, solvent etc. For example, uses
as refrigerant, making use of HFC’s excellent characteristics and being used in equipments under
confined condition, are considered to have sufficient societal benefit and importance. Namely, when
HFCs are used as refrigerant of air-conditioners / refrigerators, total GHG (greenhouse gas) emission
is composed of direct emission as refrigerant leakage and indirect emission caused by energy
consumption to run equipments, as carbon dioxide emission at power plant*1. Generally, indirect
emission occupies major part of them. Therefore, global warming impact of refrigerants should not
be compared simply by GWP, but by total global warming effect like LCCP (Life Cycle Climate
Performance)*2 that is obtained by summing of direct and indirect emission of individual
refrigeration system. As HFCs have excellent refrigerant physical properties, non-flammability and
low toxicity, energy and cost efficient designation of equipment become possible. Therefore, we can
often see the case lowering the global warming impact and energy consumption at the same time, by
adopting HFC refrigerant having higher GWP than non HFC refrigerants.
Until more excellent alternatives / alternate technologies would be available in the future, HFCs
will remain to be most important option, we should use them at applications that can make use of
their excellent feature after total evaluation of the global environment impact, safety, economics, etc.
Moreover, in order to reduce emission at application of HFCs, we should follow “Responsible Use
Principle”*3, considering energy efficient designation of equipment, prevention of leakage, recovery,
recycle and decomposition of HFC.
*1. CO2 emission intensity for electric generation in Japan in 2006 : 0.410 kg/kWh, cited from web
site of the federation of electric power companies of Japan
*2. LCCP (Life Cycle Climate Performance)
= Emission during refrigerant manufacture + Indirect emission from electric generation associated
with operating load + Direct emission from equipment operating and servicing
Example is shown in figure 3.
Equipment : Split air-conditioner,
Cooling capacity : 4.0 kW
Refrigerant recovery rate at end of life : 60%, Life of equipment : 12 year,
Location : Tokyo
Fig 3.
*3. Responsible Use Principle for HFCs
Established as voluntary principle for responsible use of HFCs by UNEP, US EPA, METI, and 25
industries organization in US, Japan, etc. in Nov. 2002.
Points are :
・Select HFCs for applications where they provide health and safety, environmental, technical,
economic, or unique societal benefits
・Minimize emissions and maximize energy efficiency at each stage of manufacture, use and
disposal of products
・Promote recovery, recycle and destruction of HFCs
・Consider alternatives that are technically, environmentally, and economically feasible