GLOSSARY

Sulfur Dioxide (SO2)

Formed by combustion of fuels containing sulfur--primarily coal and oil. Major health effects associated with SO2 include asthma, respiratory illness, and aggravation of existing cardiovascular disease. SO2 combines with water and oxygen in the atmosphere to form acid rain, which raises the acid levels of lakes and streams, affecting the ability of fish and some amphibians to survive. It also damages sensitive forests and ecosystems, particularly in the eastern part of the U.S. It also accelerates the decay of buildings. Making electricity is responsible for two-thirds of all the SO2 pollution in the U.S., 13 million tons each year.

System Power Mix

The average mix of electric power plants and other energy serving customers in a region. In the U.S., coal, other fossil fuels, and nuclear generation are the most-used sources for system power.

Tradable Renewable Certificates (TRCs)

A commodity that represent the environmental benefits of generating electricity from renewable generation sources. One REC is created each time a megawatt hour of energy from a renewable facility is generated . RECs represent how and when a unit of electricity was made at a particular generation facility and the environmental benefits (or attributes) that result from making that electricity. For example, basic attributes would be: type of generation (e.g. wind), location, , date of actual generation, emissions per MWh, if any. Environmental attributes include the emissions of NOx, SOx, CO2, mercury, and particulate matter that are avoided as a result of the wind (or other renewable) generation from that generating facility. RECs can be sold and traded for voluntary and regulatory purposes and the owner of the REC can legally claim to have purchased renewable energy.

Purchasing RECs helps ensure that more electricity is generated from renewable energy sources, which reduces the amount of electricity that has to be generated from polluting fossil fuel generation. As a result, RECs may be used to offset CO2 emissions associated with electricity usage and other sources. In addition to the carbon impact, purchasing RECs also supports renewable energy and encourages more renewable development.

Transmission Charges

Part of the basic service charges on every customer's bill for transporting electricity from the source of supply to the electric distribution company. The Federal Energy Regulatory Commission regulates retail transmission prices and services.

Transmission Lines

Interconnected electric lines which move high voltage electricity from a generation facility ultimately to the distribution lines of an electric distribution company. See Grid.

Wind power

The conversion of wind energy into more useful forms, usually electricity, using wind turbines.