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Glossary

Biogas

On the Cal-Gon dairy farm in Salem, PGE operates a facility that converts more than 20 tons of cow manure into energy each day.

Manure enters a 28-foot high digester where it releases methane gas, which then fires a generator on the farm, feeding up to 70 kilowatts of renewable electricity directly to PGE customers. Leftover materials are processed through a solids separator into relatively odor-free fibers and liquids that can be used for commercial nursery or farm soil applications.

The project started generating electricity in March 2002.

PGE hopes this system will eventually be cost-competitive with other renewable resources like wind turbines and solar power.

Biomass

Fuel derived from plant and organic matter that is used to generate electricity. Landfill gas is one of the most widely used forms of biomass generation. At those facilities, gases from decomposing organic matter are collected and burned to generate electricity. While biomass-based generation is not entirely pollution free, it does not contribute to global warming and produces much less pollution than more traditional sources of electricity.

Carbon dioxide (CO2)

CO₂ is naturally present in the Earth’s atmosphere and is a greenhouse gas considered to be the main contributor to climate change. Buying renewable energy decreases the amount of CO₂ being released into the atmosphere.

Carbon footprint

Your carbon footprint is a representation of the effect you, your home, or your business have on the climate in terms of the total amount of CO₂emissions you produce. Activities that constitute a household’s carbon footprint include electricity usage, vehicle travel, airline travel and natural gas usage.

Climate change

Climate change describes the ongoing transformation of the Earth’s average climate over time (from decades to millions of years). The majority of the world’s climate scientists have concluded that greenhouse gas emissions resulting from human activities, such as transportation and electricity production, have a significant impact on the atmosphere and are having a discernible influence on global climate.

Distribution system

The local poles, wires, transformers, substations and other equipment used to deliver electricity to end-use consumers. See “Grid.”

Energy efficiency

Refers to habit changes, new appliances or building improvements that reduce the energy used while maintaining the same benefits of lighting, heating, cooling, cleaning or other performance. Individual efforts that can be made to increase energy efficiency can be found at our Energy Efficiency Facts page.

Energy source

The primary source that provides the power that is converted to electricity through chemical, mechanical, or other means. Energy sources include fossil fuels, like coal, natural gas, petroleum and petroleum products, and renewable sources like water, wind, sunlight, geothermal, and biomass.

Geothermal

Energy generated by heat stored beneath the Earth's surface.

Green energy

Electricity that is made from renewable resources like wind, water, geothermal, solar and biomass.

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 climate change.

Green tag

See Renewable Energy Credit

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)

A measure of instantaneous power. One kilowatt equals 1,000 watts. Ten 100-watt light bulbs, for example, have a total power rating of one kilowatt.

Kilowatt hour (kWh)

A quantity of electricity usage measured by your electric meter. One kilowatt hour equals 1,000 watt hours, which is the same as running a 100-watt light bulb for 10 hours, or ten 100-watt light bulbs for one hour.

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.

New renewables

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

Oregon Public Utility Commission (OPUC)

The state regulatory agency that provides oversight, policy guidance and direction to public utilities, including electric companies like PGE.

Renewables

Energy sources that are either inexhaustible (solar, wind) or replenished over a short period of time (low impact 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 power generation. Natural gas and coal, for example, are not renewables because their use consumes fossil fuel reserves at a much quicker rate than they can be replenished.

Renewable Energy Credits (RECs), Green Tags or 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. 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. In addition to the carbon impact, purchasing RECs also supports renewable energy projects and encourages more renewable development.

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!

System power mix

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

Transmission lines

Interconnected electric lines which move high voltage electricity from a generation facility to a substation and on 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.