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Main article: "exergy
Primary energy sources are transformed by the energy sector to generate energy carriers.

Primary energy sources are transformed in "energy conversion processes to more convenient forms of energy (that can directly be used by society), such as "electrical energy, refined "fuels, or synthetic fuels such as "hydrogen fuel. In the field of "energetics, these forms are called "energy carriers and correspond to the concept of "secondary energy" in energy statistics.

Conversion to energy carriers (or secondary energy)[edit]

Energy carriers are energy forms which have been transformed from primary energy sources. Electricity is one of the most common energy carriers, being transformed from various primary energy sources such as coal, oil, natural gas, and wind. Electricity is particularly useful since it has low entropy (is highly ordered) and can be converted into other forms of energy very efficiently.

According to the "laws of thermodynamics, primary energy sources cannot be produced. They must be available to society to enable the production of energy carriers.[3]

Conversion efficiency varies; for thermal energy electricity and mechanical energy production is limited by "Carnot's theorem, and generates a lot of "waste heat. Other non thermal conversions can be more efficient, for example wind turbines do not capture all the wind energy, but generate very little waste heat, since wind energy is low entropy. In principle solar photovoltaic conversions could be very efficient, but current conversion can only be done well for narrow frequency ranges, whereas solar thermal is also subject to Carnot efficiency limits. Hydroelectric power is also converted very efficiently. The amount of usable energy is the "exergy of a system.


Primary energy outlook. Projected from 2007 ("EIA, 2010)

Energy accidents and fatalities[edit]

Energy accidents

Energy accidents are accidents that occur in systems that provide energy or power. These can result in fatalities, as can the normal running of many systems, for example those deaths due to pollution.

Globally, coal is responsible for 100,000 deaths per trillion kWh.[5]

See also[edit]


  1. ^ At the scale of "earth sciences, all primary energy sources can be considered to be renewable. The non-renewable essence of resources (PES) is due to the scale of needs within human society. In certain situations, the use of resources by human society is performed at a much higher rate than the minimum rate at which it can be geophysically renewed. This is the rationale behind the differentiation between non-renewable primary energy sources (oil, coal, gas, uranium) and renewable primary energy sources (wind, solar, hydro).
  2. ^ Some "nuclear fuels, such as "plutonium or "depleted uranium, are also used in nuclear fission power plants. However, they cannot be considered to be primary energy sources as they cannot be found in nature in any quantity. Indeed, there must be a consumption of natural uranium (primary energy source) in order to make these other nuclear fuels available.


  1. ^ a b "2014 Key World Energy Statistics" (PDF). IEA. 2014. Archived from the original on 2014-05-05. 
  2. ^ "OECD Factbook 2013: Economic, Environmental and Social Statistics". 2013. Retrieved 12 April 2014. 
  3. ^ a b Giampietro, Mario; Mayumi, Kozo (2009). The Biofuel Delusion: The Fallacy of Large Scale Agro-Biofuels Production. Earthscan, Taylor & Francis group. p. 336. "ISBN "978-1-84407-681-9. 
  4. ^ "Energy and the Natural Environment" by David A. Dobson, Ph.D., Welty Environmental Center Feature Article, accessed July 9, 2009
  5. ^ How Deadly Is Your Kilowatt? We Rank The Killer Energy Sources James Conca, June 10, 2012

Further reading[edit]

External links[edit]

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