# Energy Units and Conversion Factors

## Metric prefixes

kilo (k) = 103

mega (M) = 106

giga (G) = 109

tera (T) = 1012

peta (P) = 1015

exa (E) = 1018

Example:

1 TJ = 1,000 GJ = 1,000,000 MJ = 1,000,000,000 kJ = 1,000,000,000,000 J

1 J = 0.001 MJ = 0.000001 GJ = 0.000000001 TJ

## Volume

1 m3 = 1,000 litres (l)

1 US gallon = 3.78 l

1 Imperial gallon = 4.55 l

## Energy unit conversion

 Multiply by: GJ Toe MBtu MWh GJ 1 0.024 0.948 0.278 Toe 41.868 1 39.683 11.630 MBtu 1.055 0.025 1 0.293 MWh 3.600 0.086 3.412 1

Toe = tonnes oil equivalent

1 Mtoe = 41.9 PJ

Example: 1 MWh x 3.600 = 3.6 GJ

## Heat of combustion (high heat values)

1 l ethanol = 84,530 Btu / US gallon = 21.2 MJ / l

1 l biodiesel = 127,960 Btu / US gallon = 32.1 MJ / l

Example:

1) These values can vary with fuel and temperature.

2) Around 1.5 litres of ethanol is required to equate to 1 litre of gasoline.

3) Heat values from U.S. Department of Energy Alternative Fuels Data Center.

## Solar thermal heat systems

1 million m2 = 0.7 GWth

Used where solar thermal heat data have been converted from square metres (m2) into gigawatts thermal (GWth), by accepted convention.