Environmental impact of electricity generation

Electric power systems consist of generation plants of different energy sources, transmission networks, and distribution lines. Each of these components can have environmental impacts at multiple stages of their development and use including in their construction, during the generation of electricity, and in their decommissioning and disposal. We can split these impacts into operational impacts (fuel sourcing, global atmospheric and localized pollution) and construction impacts (manufacturing, installation, decommissioning, and disposal). This page looks exclusively at the operational environmental impact of electricity generation. The page is organized by energy source and includes impacts such as water usage, emissions, local pollution, and wildlife displacement.'The electricity sector is unique among industrial sectors in its very large contribution to emissions associated with nearly all air issues. Electricity generation produces a large share of Canadian nitrogen oxides and sulphur dioxide emissions, which contribute to smog and acid rain and the formation of fine particulate matter. It is the largest uncontrolled industrial source of mercury emissions in Canada. Fossil fuel-fired electric power plants also emit carbon dioxide, which may contribute to climate change. In addition, the sector has significant impacts on water and habitat and species. In particular, hydro dams and transmission lines have significant effects on water and biodiversity.' Electric power systems consist of generation plants of different energy sources, transmission networks, and distribution lines. Each of these components can have environmental impacts at multiple stages of their development and use including in their construction, during the generation of electricity, and in their decommissioning and disposal. We can split these impacts into operational impacts (fuel sourcing, global atmospheric and localized pollution) and construction impacts (manufacturing, installation, decommissioning, and disposal). This page looks exclusively at the operational environmental impact of electricity generation. The page is organized by energy source and includes impacts such as water usage, emissions, local pollution, and wildlife displacement. More detailed information on electricity generation impacts for specific technologies and on other environmental impacts of electric power systems in general can be found under the Category:Environmental impact of the energy industry. Water usage is one of the most obvious environmental impacts of electricity generation. All thermal cycles (coal, natural gas, nuclear, geothermal, and biomass) use water as a cooling fluid to drive the thermodynamic cycles that allow electricity to be extracted from heat energy. Other energy sources such as wind and solar use water for cleaning equipment, while hydroelectricity has water usage from evaporation from the reservoirs. The amount of water usage is often of great concern for electricity generating systems as populations increase and droughts become a concern. In addition, changes in water resources may impact the reliability of electricity generation. The power sector in the United States withdraws more water than any other sector and is heavily dependent on available water resources. According to the U.S. Geological Survey, in 2005, thermo-electric power generation water withdrawals accounted for 41 percent (201 Bgal/d) of all freshwater withdrawals. Nearly all of the water withdrawn for thermoelectric power was surface water used for once-through cooling at power plants. Withdrawals for irrigation and public supply in 2005 were 37% and 13% of all freshwater withdrawals respectively. Likely future trends in water consumption are covered here. Discussions of water usage of electricity generation distinguish between water withdrawal and water consumption. According to the USGS, “withdrawal” is defined as the amount of water removed from the ground or diverted from a water source for use, while “consumption” refers to the amount of water that is evaporated, transpired, incorporated into products or crops, or otherwise removed from the immediate water environment. Both water withdrawal and consumption are important environmental impacts to evaluate.