The Azimuth Project
Energy use (Rev #4, changes)

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Contents

Idea

Energy use varies widely depending on the context. Something can be used as a feedstock for raw materials, heat, light, or to generate mechanical power.

Energy sources

Chemical

  • Oil
  • Gas
  • Coal

Biological

  • Biomass

Environmental

  • Solar
  • Wind
  • Geothermal
  • Tidal

Uses Other

Energy sources can be used for a variety of purposes. Products from refined oil are used to make plastics and pesticides, while coal, natural gas, and even renewable electricity generation can be used to generate fertilizer. To generate power for transportation fuels refined from oil tend to be used, although natural gas is gaining popularity as a transportation fuel. Renewable energy sources tend to be used to generate electricity directly, as can chemical energy sources, although electricity generation is primarily from coal and natural gas in that context.

  • Trash

The three E’s, efficiency, exergy, and efficacy

Uses

  • Efficacy: This generally refers to the net amount of energy used for a given task. For instance if someone were to ride a bicycle down to the store instead of driving a hybrid, the efficiency of the bike ride might be lower than the efficiency of the hybrid car, but since the bicycle uses much less energy than the hybrid car it would have greater efficacy in terms of energy consumption.

  • Exergy: Exergy is a measure of the maximum useful work that can be done. The exergy of an energy sources depends on it’s use. For instance given the same amount of energy, if electricity is used via resistive heating it would provide roughly the same amount of heat that natural gas would. On the other hand, if the electricity was used to power a heat pump it could provide much more heat than it would if it was used in a resistive heater or if the equivalent amount of natural gas energy were used.

  • Efficiency: When converting energy from one form to another, we always incur some losses. These losses depend on the conversion. For example converting the chemical energy of coal to electricity is not very efficient, however converting electrical energy to chemical energy in a battery can be much more efficient. The efficiency generally depends on the process and environment.

Energy sources can be used for a variety of purposes. Some are used directly, while others are converted to different forms of energy before use. They can even be used as a feedstock for plastics, pesticides, and fertilizer among other things. To generate power for transportation, fuels refined from oil tend to be used, although natural gas is gaining popularity as a transportation fuel. Renewable energy sources tend to be used to generate electricity directly, as can chemical energy sources, although electricity generation is primarily from coal and natural gas in that context.

Liquid fuels

Most liquid fuels are derived from oil, however natural gas can be compressed to the point where it is a liquid and used as a transportation fuel. Generally speaking, per barrel of refined oil, we get about twenty gallons of gasoline, ten gallons of diesel, four gallons of kerosene, and ten gallons of other products such as heavy fuel oil and lpg. Most gasoline is used to power passenger vehicles and medium duty vehicles, while diesel tends to be used for medium and heavy duty vehicles, although it is also used for passenger vehicles. Kerosene is used in airliners and other vehicles that use turbines for propulsion. Heavy fuel oil is used to heat homes and as bunker fuel to power large cargo ships.

Solid fuels

Coal is the dominant solid fuel used in the world, although petroleum coke is also produced and used in much smaller quantities. About 60% of coal is used for electricity production, 15% is used for steel making, and the rest is used by industry for fertilizer production among other things. Trash, when properly sorted, can also be used to generate electricity and heat like fossil fuels.

Gaseous fuels

The most common source of methane is natural gas, however there are projects that capture methane from decomposing garbage. Roughly one third of world natural gas production is used for electricity, a quarter is used for heating structures, and the rest is used in industry, possibly for on site CHP. Natural gas can also be compressed to where it’s energy density approaches that of liquid fuels like gasoline and used as a transportation fuel.

Electricity

Electricity is primarily generated from the combustion of fossil fuels, however it is also generated in large part from nuclear fission, and renewables like hydro-power. It can also be generate by other renewable energy sources, but currently those represent and extremely small portion of generation. Unlike other fuels, electricity can be transmitted great distances nearly instantaneously with few losses. It is almost exclusively used to provide light, and it can also be used to provide heat and mechanical power, like fossil fuels.

References

category: energy
International Energy Outlook 2010 - Highlights