Generation Capacity

“The maximum demand that a given generator or group of generators can meet at a given time. For example, a 1,000 megawatt power plant could meet the demand of 1,000 homes using 1 kW of power simultaneously.” (AECT)


Please refer to Geo-Thermal Energy.

Geo-Thermal Energy

“This is energy available as heat emitted from within the earth’s crust, usually in the form of hot water or steam.” (IEA) In the U.S. geothermal energy is often used at the household or campus level.

In terms of a country or region that uses this to a large extent: the unique geology of Iceland allows for 25% of its total electricity production to come from geothermal power facilities. (National Energy Authority of Iceland)

Green Certificate

Green Certificate may also be known as a Renewable Energy Certificate (REC)

“A Green Certificate is a tradeable asset which proves that electricity has been generated by a renewable (green) energy source.” (

Owners of renewable generation have one REC for each megawatt of generation. They can keep or sell their certificates. REC purchasers can claim that the energy they used came from a renewable source. Such purchases support renewable power generation.

The EPA has a video on RECs at this link: RECs: Making Green Power Possible.

Greenhouse Gases

Sometimes referred to as “GHG” or “GHGs” – a term for gases that trap heat in the atmosphere; essentially, “gases that contribute to the greenhouse effect by absorbing infrared radiation (heat).” (IEA)

Primary examples of these gases as follows (courtesy of the site):

  • Carbon Dioxide (CO2): Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g., manufacture of cement). Carbon dioxide is removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle.
  • Methane (CH4): Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.
  • Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural and industrial activities, combustion of fossil fuels and solid waste, as well as during treatment of wastewater.
  • Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for stratospheric ozone-depleting substances (e.g., chlorofluorocarbons, hydrochlorofluorocarbons, and halons). These gases are typically emitted in smaller quantities, but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (“High GWP gases”).