Energy By the Numbers

  1. Food
  2. Fuel
  3. Needs
  4. Activities
  5. Embodied Energy

Food

From USDA Home and Garden Bulletin Number 72.

Food

Mass

(g)

Energy

(MegaJoules)

Density

(kJ/g)

Cheddar Cheese

28

0.477

17

Milk 2%

244

0.507

2.07

Halibut

85

0.498

5.86

Rice, wild

164

0.694

4.24

Apple

138

0.339

2.46

Fuel

From ORNL, these sources of energy are physical heat rather than edible food. These liquid fuels assume standard temperature and pressure.

Fuel

Energy

Density

Units

Ethanol HHV

23.4

MJ/litre

Propane

25.5

MJ/litre

Automotive Gasoline

34.8

MJ/litre

Jet Fuel (naptha)

35.5

MJ/litre

Crude Petroleum

38.5

MJ/litre

Diesel Motor Fuel

38.7

MJ/litre


We can also use natural solid material to provide (heat) energy. The following values also come from ORNL.

Fuel

Energy

Density

Units

Switchgrass

17.1

MJ/kilogram

Wood - HHV, bone dry

22

MJ/kilogram

Coal - Anthracite

25.2

MJ/kilogram

HHV - higher heating value

Needs

Human's Annual Energy Needs, with drastic assumptions about activity levels.

Human

Time of Life

Joules

x109

Infant

1.1456

Child

2.75

Male

3.36

Female

3.05


References

Activities

In a society grounded upon electricity, we've come to rely upon its utility. Even if wonderfully optimized, we use lots. The following associates a common household activity with its energy consumption.

Activity

Energy (kWh)

Joules

Clothes Dryer (1 load)

1.89

6792453

Clothes Washer (1 load/hot wash)

6.42

23094000

Clothes Washer (1 load/cold wash)

0.94

3396226

Electric Stove (1 family meal)

4.15

14943396

Dishwasher (1 load)

3.02

10867924

AC Central 20 degrees (1 hour)

2.64

9509433



Embodied Energy

Objects can release energy via chemical reactions as with fire. Usually, humans put much more energy into fabricating a product than what can ever come out. This emplaced energy or embodied energy, as seen in the following table, gives an indication of this great disparity.

Embodied Energy

 

MJ/kg

MJ/m

Aggregate

0.10

150

Stone (local)

0.79

2030

Concrete block

0.94

2350

Concrete (30Mpa)

1.30

3180

Concrete precast

2.00

2780

Brick

2.50

5170

Cellulose insulation

3.30

112

Steel (recycled)

8.90

37210

Steel

32.00

251200

Plywood

10.40

5720

Glass

15.90

37550

Fibreglass insulation

30.30

970

Zinc

51.00

371280

Brass

62.00

519560

PVC

70.00

93620

Copper

70.60

631164

Paint

93.30

117500

Linoleum

116.00

150930

Polystyrene Insulation

117.00

3770

Carpet (synthetic)

148.00

84900

Aluminium (recycled)

8.10

21870

Aluminium

227.00

515700


by Mark Foster Mortimer