ENERGY

Measuring Energy

Energy is measured in different units, is based on the type of energy used and the traditional industry practices. British thermal unit (Btu) is one of the earliest energy units adopted by various traders and are still in use. Joules (J), the S.I. unit of energy, are becoming more and more popular today.

Energy is transformed from one form to another to meet the final user's needs. Due to historical reasons, there is no single universal unit of energy widely accepted. Depending on energy level and final user's requirements, the energy units may be activity specific.

For low energy level activities, energy unit such as electron-volt (equivalent to 1.602 x 10^-19 joule) is commonly used in particle-related measurement.

For lifestyle energy level activities, energy unit such as kilocalorie (equivalent to the amount of heat needed to raise one kilogram of water by 1 ^oC) is widely used in the measurement of daily energy consumption.

Bulk energy is traded in volumetric or weight units and is measured in volume or weight equivalent units. Energy unit such as British Thermal Unit is used but it is still not large enough in trading activities. Millions of British Thermal Units (1 x 10⁶ Btu) and Quad (1 x 10¹⁵ Btu) are more commonly used.

Typical energy contents in primary fuels are as follows.

Energy contents of Primary Fuels
Coal	about 2.5 million BTU/ ton.
Crude oil	about 5.6 million BTU/ barrel.
Oil	about 5.78 million BTU/ barrel.
Natural Gas	about 1,030 BTU/ ft3.
Liquefied Natural Gas	about 2.5 million BTU/ barrel

Commonly used energy units include:

• British thermal unit (Btu)
  British thermal unit is the amount of energy that needed to raise the temperature of one pound of water by one degree Fahrenheit. This is the standard measurement used to state the amount of energy that a fuel has as well as the amount of output of any heat generating device.
• Calorie (Cal)
  Calorie is the amount of energy needed to raise the temperature of one gram of water one degree Celsius.
• Joule (J)
  The basic unit of energy. A joule is defined as the amount of energy expended by a force of one newton moving an object one meter in the same direction as the force.
• Kilowatt-hours (kWh)
  Kilowatts-hours measure the total amount of electricity used over time. It is also useful for measuring amounts of electricity used by appliances, such as refrigerators, and by households. Kilowatt-hours are what show up on your electricity bill. One kilowatt (kW) equals 1,000 watts, and one kilowatt-hour (kWh) is one hour of using electricity at a rate of 1,000 watts.
• Ton of oil equivalent (toe)
  Unit representing energy generated by burning one metric ton (1000 kilograms ) or 7.4 barrels of oil, equivalent to the energy obtained from 1270 cubic meters of natural gas or 1.4 metric tons of coal, i.e. 41.87 gigajoules (GJ), or 11.63 megawatt hours (MWh).

Measuring Power

Power is the rate at which energy is used. Some units of measurement for power include horsepower and watts. Like units of energy, power units can be converted into one another.

• Horsepower (hp)
  The original meaning of this unit is to measure the amount of energy required to raise coal out of a coal mine. To give a better sense of horsepower, one horsepower is equivalent to lifting 33,000 pounds for 1 foot in one minute.
• Watt (W)
  A unit of power, describe the rate at which energy is being used at a specific moment. It is the equivalent of one joule per second .

Conversion of Energy Units:
1 x calorie (cal.)	= 4.1868 joules
1 x British Thermal Unit (BTU)	= 1,055 joules
	= 252 cal.
1 x kilowatt-hour	= 3.6 x 106 joules
1 x megawatt-hour	= 3.6 x 109 joules
1 x gigawatt-hour	= 3.6 x 1012 joules
1 x ton of oil equivalent (toe)	= 4.1868 x 1010 joules
1 x million tons of oil equivalent (Mtoe)	= 4.1868 x 1016 joules