GLOSSARY

Green Tag

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.

Greenhouse Effect

The increasing mean global surface temperature of the Earth caused by gases in the atmosphere (including carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbon). The greenhouse effect allows solar radiation to penetrate but absorbs the infrared radiation returning to space.

Greenhouse Gases

A family of gases that trap radiant energy. Greenhouse gases include carbon dioxide, methane, nitrous oxide, water vapor, and halocarbons (i.e., chlorofluorocarbons). Human beings are increasing the amount of greenhouse gases in the air by burning fossil fuels. These increases affect our environment in the form of global warming and climate change.

Grid

A network for the transmission of electricity throughout a region. The term is also used to refer to the layout of an electric distribution system.

Hydro Power

The force or energy of moving water used to generate electricity.

Kilowatt (kW)

Kilowatt, the standard unit for measuring electricity demand, equal to 1,000 watts.

Kilowatt Hour (kWh)

Kilowatt-hour, the standard unit for measuring electricity energy consumption, equal to 1,000 watt-hours.

Megawatt (MW)

A term commonly used to rate the power output of electric power plants or to define large electric customer loads. A megawatt equals one thousand kilowatts, or a million watts. A large utility power plant typically has a power rating of 500 to 1,000 megawatts. One megawatt of power could supply 500 to 1,000 average homes, depending on the time of day.

Meter Read

Recording the amount of electrical energy used by homes and businesses as displayed by an electricity meter. Electricity meters are typically mounted on the exterior walls of homes and businesses. Most record total kilowatt hours of energy used per month and are usually read monthly by utility employees.

New Renewables

Any renewable energy source built (or repowered) after January 1, 1997. See Renewables.

Nitrogen Oxides (NOx)

Formed when fossil fuels (notably oil, coal, and natural gas) and biomass (plant matter, wood chips, and landfill gas) are burned at high temperatures. NOx contributes to acid rain and smog. Health effects associated with smog include damage to lung tissue, increased asthma attacks, and respiratory illness in children with frequent high-level exposure. When NOx causes acid rain, it contributes to pollution of lakes and coastal waters and the degradation of sensitive forests. This pollution is destructive to fish and other animal life. Making electricity is responsible for 25% of all the NOx pollution in the U.S., over 6 million tons each year.

Off-Peak/On-Peak

Blocks of time when energy demand is relatively lower (off-peak) or higher (on-peak).

Renewable Energy Certificate (RECs)

Renewable energy certificates (referred to as RECs, and also known as renewable energy credits) represent the environmental and other non-power attributes of renewable electricity generation and are part of most renewable electricity products.

RECs are measured in 1 mega-watt-hour (MWh) increments of power generated from renewable sources like wind, solar, hydro and biomass. They can be traded separately from the actual electricity produced by renewable facilities. Purchasing RECs ensures that the renewable electricity products you buy are generated using renewable resources, reducing the amount of electricity that has to be generated from polluting fossil fuels. RECs can also offset CO2 emissions associated with your electricity usage.

Renewables

Energy sources that are either inexhaustible (solar, wind) or replenished over a short period of time (hydro, biomass, geothermal). Most renewable energy ultimately comes from the sun - indirectly in the case of wind, water, and biomass; directly in the case of solar (PV) generation. Natural gas and coal, for example, are not renewables because their use consumes gas and coal reserves at a much quicker rate than they can be replenished.

Solar

Energy from the sun. Sunlight can be converted to electricity directly, as in the case of photovoltaic (PV) applications or indirectly as in the case of solar thermal applications. According to the U.S. National Renewable Energy Laboratories (NREL), the amount of energy from the sun that falls to the earth in one day could supply the entire world's energy needs for 27 years.