The Azimuth Project
Energy (Rev #9)


Energy refers to the capacity to do work and is commonly measured in joules. This page is an overview for energy.


A concept related to energy is power. Power is the capacity to do work over time. Power is measured in watts which are defined as joules/second. In many contexts the terms are used interchangeably since an energy source is also a source of power, and a power source supplies energy.

Energy sources have always been important for humans. Even in primitive societies, wood or charcoal is used for cooking and heating. Energy sources provided light for illumination, heat for metallurgy, heat for brick kilns, and heat for warmth during cold weather.

Some energy sources are known as fuels. A fuel is a substance which can be burned or converted to produce energy. Firewood was the first major fuel, then charcoal, then coal, then petroleum (or oil). Oil was the dominant energy source for the 20th century and remains so today.

The industrial revolution was made possible by the presence of large coal deposits which provided the fuel for steam which powered factories and train locomotives in the 19th century. Virtually all of modernity relies on energy. Energy is used to power automobiles, electrical motors, construction equipment; to heat furnaces, ovens, houses and buildings; and to distill and enable chemical reactions that require energy inputs; among other things.

Energy Crises

There are several potential crises related to energy:

  • Energy Dependency - Most countries import a portion of their energy from other countries. The most common ways to import energy are by pipeline (oil and natural gas), by tanker, and by bulk cargo ship. Geopolitical events can disrupt the supply of energy greatly harming the economies of countries dependent on imports.

  • Global warming - Fossil fuels like crude oil, natural gas, and coal are carbon-based fuels. About 85% of the worldwide energy usage came from fossil fuels in 2007. When burned the carbon in the fuels combines with oxygen to emit CO2 into the atmosphere. The burning of fossil fuels are the largest factor in the increase in CO2 concentrations which, in turn, are the major cause of global warming.

  • Peak oil - The reserves for fossil fuels are finite. At some point in the future the rate of extraction will drop off and the cost of extraction will rise. Some scientists and economists believe that we are near or approaching peak oil.


Improving the technology and economics of energy is crucial to saving the planet. For more details, start here:

Then try some of the pages listed below!

Azimuth Project pages

Energy is a ‘category’ in the Azimuth Library. For all the pages in this category, go here.

Here are some of the best:

Energy concepts

Fossil fuels

Alternative liquid fuels

Nuclear power

Solar power

Wind power


category: energy