Numbers

Energy By the Numbers

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 EnergyDensity 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 EnergyDensity 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.

HumanTime of Life Joulesx109
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

References

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
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