Introduction to the REZ Transmission Planning Process

Achieving clean energy goals may require new investments in transmission and generation, especially if planners anticipate economic growth and increased demand for electricity. The renewable energy zone (REZ) transmission planning process can help practitioners ensure their infrastructure investments achieve national goals in the most economical matter.

Defining Renewable Energy Zones (REZs) and the REZ Transmission Planning Process

A REZ is a geographic area that enables the development of profitable and cost-effective grid-connected renewable energy. A REZ has high-quality renewable energy resources, suitable topography and land-use designations, and demonstrated interest from developers, all of which support cost-effective renewable energy development.

The REZ transmission planning process is an approach to plan, approve, and build transmission infrastructure that connects REZs to the power system. The REZ process helps to increase the share of solar, wind, and other renewable energy resources in the power system while maintaining reliability and economics. The REZ process focuses on large-scale wind and solar resources that can be developed in sufficient quantities to warrant transmission system expansion and upgrades.

What is the REZ transmission planning process?

The six steps of the REZ transmission planning process are outlined in the figure below. These steps are individually described in the pages that follow, providing detailed description of their purpose, outputs, and the key decision makers and stakeholders involved. These steps consist of:

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Figure. Renewable energy zone transmission planning process outline

Why is the REZ transmission planning process advantageous?

REZ transmission planning is a process to plan, approve, and build transmission infrastructure that connect REZs to the power system. The REZ process helps to increase the share of solar, wind, and other renewable energy resources in the power system while maintaining reliability and economics. The REZ process focuses on large-scale wind and solar resources that can be developed in sufficient quantities to warrant transmission system expansion and upgrades. These variable renewable energy resources are similar to large hydropower in that transmission systems must be brought to the location of the resource to connect them to the grid.

The REZ process focuses on large-scale wind and solar development because other renewable energy resources (such as geothermal or mini-hydropower) are seldom found in sufficient concentration to warrant consideration as a REZ. However, when located within a designated REZ, these supplemental renewable energy resources may provide additional value to a designated REZ.

Who should use the REZ Guidebook, and how?

The REZ Guidebook seeks to help power system planners, developers, key decision makers, and stakeholders understand and use the REZ transmission planning process to integrate transmission expansion planning and renewable energy generation planning.

The first sections of this guidebook present the organizational structure of the REZ process and an outline of the steps involved in the process. The remaining sections describe each step of the REZ process in detail.

Has the REZ process been applied before?

The broad outline presented in the REZ Guidebook is based on the Competitive Renewable Energy Zones (CREZ) process used in Texas between 2005 and 2015 (see The REZ Process: Organizational Structure) and may be modified based on unique circumstances.