Exploration of Resource and
Transmission Expansion Decisions in
the Western Renewable Energy Zone
Initiative
Feb 24, 2010 - eetd.lbl.gov
Abstract
Building transmission to reach renewable energy (RE) goals requires coordination among
renewable developers, utilities and transmission owners, resource and transmission planners,
state and federal regulators, and environmental organizations. The Western Renewable Energy
Zone (WREZ) initiative brings together a diverse set of voices to develop data, tools, and a
unique forum for coordinating transmission expansion in the Western Interconnection. In this
report we use a new tool developed in the WREZ initiative to evaluate possible renewable
resource selection and transmission expansion decisions. We evaluate these ecisions under a
number of alternative future scenarios centered on meeting 33% of the annual load in the
Western Interconnection with new renewable resources located within WREZ-identified
resource hubs.
Of the renewable resources in WREZ resource hubs, and under the assumptions described in this
report, our analysis finds that wind energy is the largest source of renewable energy procured to
meet the 33% RE target across nearly all scenarios analyzed (38-65%). Solar energy is almost
always the second largest source (14-41%). Solar exceeds wind by a small margin only when solar
thermal energy is assumed to experience cost reductions relative to all other technologies.
Biomass, geothermal, and hydropower are found to represent a smaller portion of the selected
resources, largely due to the limited resource quantity of these resources identified within the
WREZ-identified hubs (16-23% combined). We find several load zones where wind energy is the
least cost resource under a wide range of sensitivity scenarios. Load zones in the Southwest, on
the other hand, are found to switch between wind and solar, and therefore to vary transmission
expansion decisions, depending on uncertainties and policies that affect the relative economics of
each renewable option. Uncertainties and policies that impact bus-bar costs are the most important
to evaluate carefully, but factors that impact transmission costs and the relative market value of
each renewable option can also be important. Under scenarios in which each load zone must meet
33% of its load with delivered renewable energy from the WREZ-identified resource hubs, the
total transmission investment required to meet the 33% west-wide RE target is estimated at
between $22 billion and $34 billion. Although a few of the new transmission lines are very long—
over 800 miles—most are relatively short, with average transmission distances ranging from 230-315 miles, depending on the scenario. Needed transmission expenditure are found to decline to
$17 billion if wide use of renewable energy credits is allowed; consideration of renewable
resources outside of WREZ-identified hubs would further reduce this transmission cost estimate.
Even with total transmission expenditures of $17-34 billion, however, these costs still represent
just 10-19% of the total delivered cost of renewable energy.
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