Environmental Engineering Reference
In-Depth Information
Material
Source
Embodied energy MJ/kg
Bricks
Fired clay
2-5
Concrete
Raw materials 6-12
Copper
Ore
60-150
Cotton
Standing plant 140
Glass
Silicon sands
15-30
Iron
Ore
20-25
Lead
Ore
30-50
Oxygen
Air
6-14
Paper
Wood pulp
25-35
Polyethylene Crude oil
75-115
Silicon (pure) Silicon sands
1,400-4,100
Steel alloy
Iron ore
30-60
Timber
Forestry
1-3
Water
Streams
< 0.01
Source:
Smil (
2008
).
The energy sector is, itself, another big spender of energy. Between 10 per cent and 20
per cent of the energy contained in crude oil is expended in its extraction, transportation
and refinement into lighter combustion fuels such as petrol and diesel. Though coal and gas
do not need to be refined, 5 per cent to 10 per cent of their inherent energy is expended in
extraction and transportation to power plants and homes. Another 10-20 per cent is used
to build and run the power plants and to carry the electricity to the site of consumption.
