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Energy development
Schematic of the global sources of energy in 2010
Total Renewables split-up by source
   Fossil
   Renewable
   Nuclear
   Geo-heat
   Hydro
   Ethanol
   Biodiesel
   Wind
   Solar PV
   Solar CSP
   Oceanic
Source: Renewable Energy Policy Network
World total primary energy production
World total primary energy production
  Total world primary energy production (quadrillion Btu)
   China
   Russia
   Africa
   United States
   Europe
   Central and South America
Note the different y-axis for total (left) and regional curves (right)
US Energy Use/Flow in 2011
Estimated US Energy Use/Flow in 2011. Energy flow charts show the relative size of primary energy resources and end uses in the United States, with fuels compared on a common energy unit basis.
Energy flow charts show the relative size of primary energy resources and end uses in the United States, with fuels compared on a common energy unit basis (2011: 97.3 quads).

Compounds and Radiant Energy
   Solar
   Nuclear
   Hydro
   Wind
   Geothermal
   Natural gas
   Coal
   Biomass
   Petroleum

Producing Electrical Currents/Utilizing Effects Transmitted
   Electricity generation
   Residential, Commercial, Industrial, transportation
   Rejected energy (waste heat)
   Energy services

Energy development is the field of activities focused on obtaining sources of energy from natural resources. These activities include production of conventional, alternative and renewable sources of energy, and for the recovery and reuse of energy that would otherwise be wasted. Energy conservation and efficiency measures reduce the demand for energy development, and can have benefits to society with improvements to environmental issues.

Societies use energy for transportation, manufacturing, illumination, heating and air conditioning, and communication, for industrial, commercial, and domestic purposes. Energy resources may be classified as primary resources, where the resource can be used in substantially its original form, or as secondary resources, where the energy source must be converted into a more conveniently usable form. Non-renewable resources are significantly depleted by human use, whereas renewable resources are produced by ongoing processes that can sustain indefinite human exploitation.

Thousands of people are employed in the energy industry. The conventional industry comprises the petroleum industry, the natural gas industry, the electrical power industry, and the nuclear industry. New energy industries include the renewable energy industry, comprising alternative and sustainable manufacture, distribution, and sale of alternative fuels.

Classification of resources