9 TEWI Assessment of Conventional and Solar Powered Cooling Systems
159
GWP for Electricity Generation
Electricity is required to drive the VCR, and most of the electricity generation sources
are fossil fuel based. For example, in Japan, the most share of the electricity is generated from gas (39.2%), coal (33.7%) and oil (8.2%). Other sources are hydro (8.2%),
solar PV (4.9%), waste (1.8%), nuclear (1.7%), biofuels (1.4%), wind (0.6%), and
geothermal (0.2%) (IEA 2018). Combined CO 2 emission factor for per unit electricity generation is 0.518 kg for Japan (Electricity Review Japan 2018). Developing
and underdeveloped countries have much higher GWP for per unit of electricity
generation.
Weight of the Cooling System
Choosing raw materials is crucial to building various parts of an air-conditioner. The
objective is to reduce the mass, increase the efficiency and decrease the cost. Different parts of the air conditioners are made of different metals, plastic and steel (Rude
2019). Frames and base structures are usually made of corrosion resistant stainless
steel. Heat exchangers and fins are typically made of Aluminum. Additionally, copper is chosen for tubing of condenser and evaporator. Copper has relatively higher
thermal conductivity, higher tensile strength, lower thermal expansion coefficient
than Aluminum. However, Aluminum is lighter and cheaper than Copper. In this
assessment, we have considered that 50% is stainless steel, 20% is copper, 20% is
Aluminum and 10% other materials of total weight.
GWP of Raw Materials Production
Building materials of a cooling system are mostly metals. These metals are usually
extracted from ores. The extraction process includes heating in high temperature
furnace, electrolysis of molten compounds, refining, shaping, cutting, and so forth.
A large amount of energy is required to obtain the metals in usable form to build a
cooling system. Hence, the raw materials that are used in the cooling system also
contribute to global warming.
System Lifespan
An average life expectancy of the cooling system is considered 15 years. Since TEWI
is usually calculated on per year basis, lifespan is necessary to calculate the annual
indirect warming impact to build the system.
159
GWP for Electricity Generation
Electricity is required to drive the VCR, and most of the electricity generation sources
are fossil fuel based. For example, in Japan, the most share of the electricity is generated from gas (39.2%), coal (33.7%) and oil (8.2%). Other sources are hydro (8.2%),
solar PV (4.9%), waste (1.8%), nuclear (1.7%), biofuels (1.4%), wind (0.6%), and
geothermal (0.2%) (IEA 2018). Combined CO 2 emission factor for per unit electricity generation is 0.518 kg for Japan (Electricity Review Japan 2018). Developing
and underdeveloped countries have much higher GWP for per unit of electricity
generation.
Weight of the Cooling System
Choosing raw materials is crucial to building various parts of an air-conditioner. The
objective is to reduce the mass, increase the efficiency and decrease the cost. Different parts of the air conditioners are made of different metals, plastic and steel (Rude
2019). Frames and base structures are usually made of corrosion resistant stainless
steel. Heat exchangers and fins are typically made of Aluminum. Additionally, copper is chosen for tubing of condenser and evaporator. Copper has relatively higher
thermal conductivity, higher tensile strength, lower thermal expansion coefficient
than Aluminum. However, Aluminum is lighter and cheaper than Copper. In this
assessment, we have considered that 50% is stainless steel, 20% is copper, 20% is
Aluminum and 10% other materials of total weight.
GWP of Raw Materials Production
Building materials of a cooling system are mostly metals. These metals are usually
extracted from ores. The extraction process includes heating in high temperature
furnace, electrolysis of molten compounds, refining, shaping, cutting, and so forth.
A large amount of energy is required to obtain the metals in usable form to build a
cooling system. Hence, the raw materials that are used in the cooling system also
contribute to global warming.
System Lifespan
An average life expectancy of the cooling system is considered 15 years. Since TEWI
is usually calculated on per year basis, lifespan is necessary to calculate the annual
indirect warming impact to build the system.