Western Renewable Energy Zones Glossary

Avoidance Areas
Areas within Candidate Study Areas and/or Renewable Energy Zones where development of renewable energy resources should not occur because of purpose, policy, or other restrictions related to environmental, land use or other issues.

Busbar Cost
The per megawatt-hour revenue that a project would have to earn in order to break even on all development and operating costs, other than network transmission. Busbar cost includes any collector lines bringing power from dispersed generators to a central interconnection point on the transmission system. The busbar is the point at which the aggregate output of multiple units is metered, and is the point at which the units become subject to power-control area dispatch instructions.

Candidate Study Area
An initial modification of National Renewable Energy Lab base resource maps including any criteria identified by the work groups for Zone Identification and Technical Analysis and Environment and Lands. The Candidate Study Areas incorporate filters to identify a minimum threshold of developable resources, as well as state/province specific criteria. Identifying CSAs is an interim step the WREZ work groups will take in the process of developing proposed Renewable Energy Zones.

Categorization Criteria
Criteria developed by the Environment and Lands work group to categorize areas within a Qualified Resource Area and/or Renewable Energy Zone based on wildlife sensitivity.

Centroid
A centroid is a central point or logical collection point in a Renewable Energy Zone. Small generators will likely be dispersed throughout a REZ. The collector feeder lines from the generators will all converge at the centroid that connects to the bulk transmission grid.

Collector Line/System
A single or group of transmission lines that links one generator or a group of generators to the bulk power grid.

Delivered Cost of Generation
The delivered cost of generation is the phrase to define the economic cost of providing power to the consumer. This measure includes both the cost of generating power at the power plant and the cost of delivering the power over the transmission system to the end-user.

Exclusion Areas
Areas within Candidate Study Areas and/or Renewable Energy Zones where development is already precluded by statute or regulation (federal, provincial, state or local).

Load Center
Load center refers to major cities or metropolitan areas with large concentrated populations. Load centers consume large amounts of electricity.

Load-serving Entity
Load-serving Entity (LSE) is the broad term to describe entities that deliver electricity to end-users and wholesale customers, typically utility companies.

Megawatt
A watt is a unit of measure of power. One watt is equal to one joule of energy per second. A megawatt (MW) is equal to one million watts. The MW is a unit of electric power typically used in large scale electric planning. Many conventional electric power plants are defined by their nameplate capacity in MWs that typically range in amounts from 50 MWs to 250 MWs to 1000 MWs. The demand or use of electricity at a given instant is also defined in terms of MWs. In 2005, peak summer demand for electricity in the Western Electricity Coordinating Council area was 149,147 MW.

Non-Renewable Energy Zone Resources
Non-REZ resources serve sub-regional or in-state demand. These renewable energy resources that are not located in a REZ do not require multi-billion-dollar investments in extra-high voltage transmission extending across state lines. They primarily serve load in the same locality, state or utility service area. They do not need to be concentrated in one place in order to be developed, as development is unambiguously within the regulatory purview of the state where the resource is located. Finally, the ability of any state to develop them is largely unaffected by policies in neighboring states.

Qualified Resource Area
Qualified Resource Areas represent those lands with the greatest energy density within a contiguous area for each respective state. Initially, the WREZ Technical Committee created a basic set of renewable energy resource criteria to identify Candidate Study Areas that were then refined into QRAs. A QRA excludes any lands with statutory or regulatory development limitations and limitations related to topography, ground cover, or urban settlement. After public comments have been considered and sensitive areas for wildlife included, QRAs may be adjusted and/or identified as Renewable Energy Zones for future transmission modeling and planning purposes.

Renewable Energy Zone
Areas with high concentrations of developable renewable energy resources that can meet regional energy demand.

State Task Group
A task group established by the Western Governors’ Wildlife Council to participate in the WREZ project to categorize wildlife sensitivities within Qualified Resource Areas and/or Renewable Energy Zones.

Substation
An electrical substation serves as a link among generator, transmission and distribution systems. Substation transformers convert high voltage energy to low voltage energy and vice versa.

Supply Curve
A representation of the amount of renewable energy capacity that is economically developable from an area, and the cost at which increments of the total can be developed. The curve depicts projects and potential projects in ascending order according to their busbar costs. A Renewable Energy Zone supply curve includes and identifies all economically developable renewable energy technology categories contained in the REZ.

Transmission Segment
A transmission segment defines a discrete distance from two points along a transmission path. Transmission segments were identified in the WREZ project to calculate the distances from Renewable Energy Zones to load centers.

Western Electricity Coordinating Council
The Western Electricity Coordinating Council is an organization that promotes and regulates electric reliability across the Western Interconnection. WECC also conducts transmission planning and supports Western power markets.

Western Governors’ Wildlife Council
The Western Governors’ Association established the Western Governors’ Wildlife Council to coordinate and oversee implementation of the WGA Wildlife Corridors report endorsed by the Governors in June 2008. Each WGA member Governor appoints a representative to the WGWC. The mission of the WGWC is to identify key wildlife corridors and crucial habitats in the West and coordinate implementation of needed policy options and tools to conserve those landscapes

Western Interconnection
The Western Interconnection is a synchronized electric grid that spans 1.8 million square miles from the Canadian provinces of British Columbia and Alberta, to the northern part of Baja California, Mexico. The Western Interconnection covers all or most of 11 states (Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming), and portions of three states (South Dakota, Nebraska, and Texas). In addition to the Western Interconnection, there are the Eastern Interconnection and the Electrical Reliability Council of Texas (ERCOT) in the United States.