Climate Change

1. An example of what it means to let a lightbulb of 100 W emit
light continuously for 1 year
 We assume electricity generation is by a coal power
plant. The energy density of coal is roughly 6.7 kWh/kg
(kWh = kilowatt-hour) . This corresponds to 0.765 Wy
(Watt-year. Conversion of coal to electricity has an
efficiency of 40%. So, 1 kg coal can generate 0.4 x 0.765
= 0.306 W for 1 year. Inversely, to generate 100 W for 1
year, we need 326 kg of coal. [79]
(Note that 100 Wy = 876 kWh)
 How much CO2 is emitted during that time?
 CO2 emission from coal = 2.3 kg/kg coal
(anthracite)
 So, 326 kg coal emits 750 kg CO2 in the atmosphere
From EIA

2. How does this energy compare with the energy needed to heat
1000 L of water from 20 to 100 °C?
Answer: Roughly 1/10th of the amount of energy that is needed to let a lightbulb
of 100W emit light one year long.
1 cal heat increases the temperature of 1 g of water with 1 °C
1 kcal increases the temperature of 1 kg (1 L) of water with 1 °C
80 kcal brings 1 L of water from 20 °C to 100 °C
1 kcal = 1.162 Wh
80 kcal = 93 Wh
Thus, 93 kW can increase the temperature of 1000 L water from 20 to 100 °C. If
this rise needs to be achieved in 1 hour, energy use is 93 kWh, which is roughly
1/10th of the amount of energy that is used to let a lightbulb of 100W emit light
one year long (876 kWh as shown in previous slide).
To increase the temperature with 80 °C 10 times faster (within 6 min), 930 kW
would be required during that time span.

3. Household energy consumption
 Space heating and cooling makes 40-60 % of the average residential energy needs, followed by
lighting and other appliances and water heating.
Source UK
Source US: EIA
0
10
20
30
40
50
60
70
Space
heating/cooling
Lighting &
household
machinery
Lighting Water heating Cooking
%
Household energy consumption
U.K. U.S.

4. Energy consumption for space heating by type of home
(in the Netherlands)
Home type
Natural gas
consumption
(m³) kWh/year
Electricity
kWh/year
CO2 emission from
gas combustion
tons /year
Flat 900 9 180
Row house 1 350 13 770
Edge house 1 590 16 218
Twin house 1 670 16 218
Single house 2 220 22 644
Average 1 440 14 688
Hazenpad 2,
Linden *
3 800 38 760 4 900 22
* Total energy consumption = 43 660 kWh/year
Source: HOME 2012, ECN

5. Energy consumption for lighting by sector

6. Energy consumption for lighting by type of bulb
Watt per lumen
 Incandescent light bulbs consume ~ 3-5 x more energy for the same amount of light (expressed in
lumen) than fluorescent or LED bulbs. Incandescent light bulbs are now forbidden in the EU.
CFL = compact fluorescent bulbs
LED = light emitting diode

7. Life span and embodied CO2 emissions by bulb type
 The average life span of an LED bulb is 25 times longer than that of an incandescent light bulb. The
CO2 emissions from the energy to produce and use the bulb is 4 x larger for an incandescent than for a
LED bulb. Source

8. Embodied energy of materials
The embodied energy of an object is the energy it takes to produce 1 kg of that object. It includes
the energy of each step in the production, including its transportation and disposal. It also
includes all the indirect energy required, i.e., all the energy required to manufacture the
equipment and materials needed to manufacture the object, e.g. trucks, mining equipment,
etc. Source See also LCA
0
5
10
15
20
25
30
35
40
45
50
kWh/kg
Embodied energy

9. Embodied energy of a car
 Treloar, et al. have estimated the embodied energy in an average automobile in Australia as
270 GJ (gigajoules) (= 75 000 kWh) with a life span of 15 years for the car. Note that the
CO2 emission to make a car = 16 tons (0.27 kg/kWh). For all cars in the world (~1
billion) that would be 16 gigatons [Ref]erence] .
 A similar calculation is based on the Toyota Prius, an energy efficient car on the road.
Embodied energy is 165 GJ, half of which is in steel and aluminium. This is 40 % lower
than the average Australian car (from: click here).
1 GJ= 31.71 x 10-12 TWy = 277 780 x 10-12 TWh = 277 780 x 10-3 kWh = 278 kWh 1MJ = 0.278 kWh
From wattzon.com

10. Effective energy for driving a car
 How does that embodied energy of a car compare to the energy used for driving the car
(only in terms of gasoline consumption)?
 Energy density of gasoline is 9.6 kWh/L
 Assuming the car uses 8 L gasoline per 100 km and the car travels 20 000 km/year,
1600 L gasoline is consumed/year
 This corresponds to 15 360 kWh/year and 2.9 tons CO2 emission.
 Thus, roughly 5 x more energy is used to make a car than to drive that car over
a distance of half the cicumference of the Earth.
 Note that there are ~1 billion cars in the world, that the average time a car is on the
road is 1 hour/day and that the number of passengers is 1.6/car. It is clear that
individualized transportation in developed countries is economically extremely
inefficient. The main reason of why people live with these figures is the easyness and
freedom in mobility.
 Driving a conventional car is also thermodynamically less efficient than an electric
transportation vehicle, since energy conversion efficiency of an internal combustion
motor is 10-50 % vs 40-90 % for an electric motor.

11. Energy consumption by transportation type per passenger.km
 Source (Japan)  Source: U.S. Department of
Transportation
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Rail
(commuter)
Car Bus
(transit)
Air Taxi
KWh/passenger.km
Transportation energy by vehicle type
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Rail Bus Air Sea Car
kWh/passenger.km
Transportation energy by vehicle type

12. Embodied energy of food
Food
Energy
(kWh) to
Produce 1
kg
Efficiency *
(%)
Source Source
Corn 1 102
Milk 1.65 45
Apples 3.7 15
Eggs 8.8 19
Chicken 7 15
Cheese 14.8 31
Pork 27.7 8.5
Beef 69.3 4.3
* Potential energy in food as a proportion of the energy needed to produce that food
The embodied energy of food is the energy it takes to produce 1 kg of that food.