EES 119/219
Lecture 9
Energy production
and consumption
•
The big
issues:
–
Population
growth (Fig.1)
–
Growth
in per capita consumption (Fig. 2)
–
Inequality
of energy consumption (Fig. 3)
Current use – easy
numbers
•
Average
use per person:
–
World 2 kW
–
•
à Total use
–
World: 2 kW/person x 6.4 x109persons = 12.8x1012W à 12.8 TW
–
Origin of Energyà
Energy Sources
•
Categories
based on rates of use and replenishment
•
Exhaustible: rate of replenishment much slower than rate of use: Fossil fuels; thermal
fission
•
Renewable: rate of replenishment comparable to human life time: Wood; biomass
•
Sustainable: rate of use small compared to available reservoir: solar energy
(including hydro; wind); geothermal; breeder fission; fusion
Schematic history of
energy use (Fig. 4)
•
Current
energy sources
–
Predominantly
fossil fuels: 80à90 %
–
Currently
in use:
•
Coal
•
Oil
•
Natural
gas
–
Future
use: unconventional hydrocarbons
•
Shale
oil
•
Tar
sands
•
Coalbed
methane
•
Gas
hydrates
Coal
•
Observations:
–
Sedimentary
rock rich in organic material
•
Mostly
C, little H, O
–
Coal
seams are 1à 20 m thick
–
Layers
of mudstone, siltstone or sandstone are common in coals fields
Energy content of coal: 2.72x107 J/kg
The formation of coal is related to the carbon cycle (Fig. 5)
Steps in the formation of coal (Fig.
6)
As the rank of coal increases, carbon content and energy
content increase, but O and H contents decrease (Fig. 7)
The age distribution
of coal reflects two maxima, one in the Carboniferous and one in the
Creataceous/early Tertiary (see Fig. 5.11)
Most of the coal
deposits are in the Northern Hemisphere (Fig. 5.15), the