Glossary Terms

Wind Rose

A wind rose shows the direction and the frequency of that direction that the wind blows at a particular location. Wind roses are used in wind projects to portray the amount of energy that comes into the wind project from various directions.

Wake Losses

The space behind a wind turbine that is marked by decreased wind power capacity due to the fact that the turbine itself used the energy in turning the blades. The wind behind the turbine, in its wake, is less effective at generating energy for a certain distance in the downwind direction due to turbulence created by the upwind machine.


The process of separating a service into component parts (generation, transmission, distribution, ancillary services, etc) to allow customers to choose where to buy each service separately. Utility unbundling, overseen by regulators, generally requires utilities to ensure that the price of each service accurately reflects the cost of that service (plus a margin for profit). In this way, unbundling helps ensure that customers pay for what they receive and are not forced to subsidize services they do not use.


A device for converting the flow of a fluid (air, steam, water, or hot gases) into mechanical motion that can be utilized to produce electricity.


A standardized set of terms for generation, purchase, transmission and/or delivery of electricity on a utility’s system, a state, region, or country. The term is commonly used in electric utility rate making in North America. The term is also commonly used in Europe. In this context tariffs are not taxes or customs duties on goods crossing international borders.

System Benefits Charge (SBC)

A required fee (also known as a public benefits charge) from all electricity customers to fund programs that are in the public interest that may or may not be competitive in a deregulated electricity market. These programs include energy conservation, support for renewable energy use, subsidies for people with low-income, and research, development and pilot project construction for new technologies.


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