Home » Wood pellets » Units of energy

Units of Energy

The unit of energy in the I.S.-system(Systéme International) is the Joule. Besides the 'Joule' there are some other units that are still used, like the calorie, BTU, and BOE.

A brief summary...

The Joule

The Joule is named after James Prescott Joule and is the IS-unit of energy.
Joule can be written in meters, kilograms and seconds:

• 1 Joule = 1kg.m²/s² = 1W.s= 1 N.m.

Eén joule is defined as:

• the energy required to lift a weight of 1 newton 1 meter up (1 newton on earth is a mass of roughly 100 grams).

In nutrition the energy content of food is expressed in kJ..
Calculating Joules in kWh is simple: 1 kWh = 3600 kJ.

1 Joule = 1W.s =
0,23987 - 2,2391	Calorie
0,000948	BTU
1/3.600.000	kWh

The Calorie

Before the Joule was introduced, people used the calorie as an unit of energy or heat. Professor Nicolas Clément introduced this unit in 1824. The original definition was based on the kilogram:

• 1 Calorie is the enrgy required to heat 1 kilogram of water by 1 degree Celsius

There are many sligthly different versions of this definition. The most important one is based on grams instead of the kilogram. A (gram)calorie is 100 times smaller then a (kilogram)calorie. Other versions are based on different begin temperatures of the heated water (4 °C, 15 °C of 20 °C).
Values (in J) of (gram)calorie range from 4,182 J to 4,190 J. In thermodynamics 1 (gram)calorie equals 4,184 J.

1 (gram)calorie =
4,182 - 4,190	Joule
0,00397	BTU
0,0000012	kWh

The BTU

The BTU is used in the US and Canada as a unit of energy content of fuels.
One BTU of British Thermal Unit is:

• The heat required to heat 1 pound of water with one degree Fahrenheit.

The heating power of a stove or boiler can be expressed in BTU/hour (BTU/h).

1 BTU =
1054-1060	Joule
252-253	cal
0,000293	kWh

The BOE

BOE stands for the term Barrel of oil equivalent. One BOE is the amount of energy that is released by using one barrel of crude oil or 1700 kWh.


Calculator
A handy website to convert these units and others is Convertworld.com.

Other info:

Wikipedia - Conversion of units