Energy Sources: History, Selection, and Transitions

Janet Patton, NDSU Central Grasslands Research Extension Center, Streeter, ND


The history of civilization is linked to energy and its sources. For thousands of years, we have depended on sunlight, muscle power, and fire for the energy we need. We also rely on the forces of nature: heat and light from the sun, the solar energy stored in fossil fuels and biomass, wind and water, atomic energy, and heat from within the Earth.

Primary sources of energy are those that create heat directly, and may be divided into non-renewable sources (coal, petroleum, natural gas, and nuclear) and renewable sources (hydropower, biomass, wind, geothermal, and solar). Secondary sources, such as electricity and hydrogen, require energy from other sources for their generation.

Energy itself is found in several forms. Muscles, water, and wind produce mechanical energy. Chemical energy is converted to thermal energy during the combustion of fuels. This heat may be used directly or transformed into mechanical energy to run engines and turbines for transportation and the generation of electricity.

The subject of energy is a complex one, encompassing science, engineering, agriculture, economics, history, and politics. This report is an overview of many of these aspects of energy throughout history, as well as its global and national importance today, along with a look at the energy industry in North Dakota. A list of terms and units may be found in Table 1.


Table 1.

Energy Terms

power = rate at which energy is transferred; energy flow

energy density = amount of energy per unit mass

efficiency of energy conversions (or production) = output to input ratio

energy intensity = cost of product or service in energy units


1 newton = a unit of force that produces an acceleration of 1 meter per second per second on an object weighing 1 kilogram

1 joule (J) = the amount of work done by a force of one newton over a distance of     one meter

1 watt (W) = electrical flow of 1 joule per second

1 kilowatt (kW) = 1,000 watts (the rate of electrical flow) (= 3,412 Btu or 3.6 million joules)

1 megawatt (MW) = 1,000 kilowatts

1 kilowatt-hour (kWh) = 1 kilowatt used in 1 hour (rate over time = an amount of electricity)

1 horsepower (hp) = 746 watts

1 British thermal unit (Btu) = heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit. (= 1,055 joules)

1 quad Btu = 1 quadrillion British thermal units

1 barrel (bbl) = 42 gallons (A barrel of crude oil equals 5.80 million Btu)

Table of Contents

NDSU Central Grasslands Research Extension Center