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

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 Wh80 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.

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 UKSource US: EIA

Space

hea

ting/

cool

ing

Light

ing

& h

ouse

hold

mac

hine

ry

Light

ing

Wat

er h

eatin

g

Cooki

ng0

10

20

30

40

50

60

70

Household energy consumptionU.K.U.S.

%

Energy consumption for space heating by type of home

(in the Netherlands)

Home typeNatural 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

Energy consumption for lighting by sector

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

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

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

Bricks

Cemen

t

Timber

Ceramic ti

lesGlas

sSte

el

Iron

Lead

Fine p

aper

Copper

Stainles

s stee

l

Plastics

Rubber

Aluminium 0

5

10

15

20

25

30

35

40

45

50

Embodied energy

kWh

/ kg

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

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.

Energy consumption by transportation type per passenger.km

Source (Japan) Source: U.S. Department of Transportation

Rail (com-muter)

Car Bus (transit)

Air Taxi0

0.5

1

1.5

2

2.5

3

3.5

4

4.5Transportation energy by vehicle type

KW

h /

pass

enger.

km

Rail Bus Air Sea Car0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8Transportation energy by vehicle type

kW

h /

pass

enger.

km

Embodied energy of food

Food

Energy (kWh) to

Produce 1 kg

Efficiency * (%)

Source Source

Corn 1 102

Milk 1.65 45

Apples 3.7 15Eggs 8.8 19

Chicken 7 15Cheese 14.8 31

Pork 27.7 8.5Beef 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.