14 Mar
The Department of Energy unveiled its draft Transmission Needs Study last month, which highlights the need for a vastly expanded electric grid to transport clean power across the country and ensure all Americans have access to reliable, cheap energy — both today and decades in the future.
Unfortunately, the U.S. has fallen far behind when it comes to building a grid capable of meeting our energy needs. Those needs are constantly evolving, too, as the transportation and building sectors electrify and extreme weather events becomes more frequent. As DOE acknowledges in its report, high-capacity power lines can take many years to develop, so transmission planning “should be defined as much by anticipated future need as current need.”
ACEG believes it is essential to incorporate those anticipated future needs — and long-term electric reliability considerations — into transmission planning. And we have advocated for a strong FERC rule to require exactly that. But state and regional authorities don’t need to wait for FERC; they should act now to plan for the future, and DOE’s report can serve as a helpful tool.
In the study, DOE clearly and powerfully emphasizes how expanded interregional transmission will make the grid more resilient in the face of extreme weather and other disruptions. When regions can access diverse generation resources from a large geographic area, it increases grid flexibility and provides crucial “insurance” in the event of localized disruptions.
Based on a review of existing literature — including key studies from NREL and Princeton University — DOE identifies where new transmission is most needed, and explores how each region can benefit from a better grid. The greatest value, according to DOE, would come from connecting ERCOT to the Western and Eastern Interconnection, followed by enhancing connections between SPP with the Mountain region of the Western Interconnect and MISO to the east.
Overall, DOE states the U.S. would need a 57% increase in transmission and a 120% increase in interregional transfer capacity by 2035 to support new clean energy resources and increased electrification. To give just one example, on a regional level, the Mountain region would need 85% more transfer capacity with the Plains to achieve this goal.
The study also explores how to plan between regions. For example, models suggest the best way to alleviate congestion between the Midwest and Delta regions is to build more transmission between the Midwest and the Plains and between the Plains and the Delta — rather than between the Midwest and Delta directly.
DOE is seeking comments on its draft study by April 20. The report is only step one in a longer process of identifying specific transmission lines that can bring the U.S. closer to a truly modern grid, but it is still an important product that can help inform transmission expansion across the country. ACEG encourages states and regional authorities to incorporate DOE’s insights into their planning and infrastructure expansion programs — so they can better prepare to meet the present and future energy needs of their communities.
What Does Each Region Need?
DOE modeled transmission needs based on a future with moderate load growth and high clean energy penetration, a future the department considers its “new normal” for planning purposes thanks to the Inflation Reduction Act.
The following is an overview of transmission needs by region, according to DOE’s review.
Northwest
- Increase transfer capacity between the Northwest and Mountain regions to meet expected load and generation growth.
- Alleviate unscheduled flows between California and the Northwest.
Mountain
- Increase transfer capacity between the Mountain region and its neighbors in the Western Interconnection by 88%.
- Upgrade transmission along the eastern edge of the region to protect system reliability in the Western Interconnection as transmission is expanded along the coast.
- Alleviate unscheduled flows on three qualified paths within the region.
California
- Alleviate unscheduled flows between California and the Northwest.
- Increase transfer capacity between the Mountain region and California by 88% relative to 2020.
- Improve the interregional transmission system to integrate new generation resources aligned with California’s clean energy policy.
- Alleviate unscheduled flows between California and the Northwest.
Southwest
- Increase transfer capacity between the Southwest and Texas across the interconnection seam to alleviate transfer limits, particularly when it comes to reliability and resource adequacy needs.
- The value of new transmission between the Southwest and Texas was the highest of all transfers that DOE considered, and the value has been increasing in recent years.
- Increase transfer capacity between the plains by 914% to meet future load and clean energy needs.
Texas
- Increase transfer capacity between Texas and the Eastern and Western Interconnections to alleviate transfer limits, meet resource adequacy needs, and address capacity shortages during periods of emergency.
- Increased interregional transmission between the Southwest and Texas was the most-valuable transfer among those DOE considered.
Plains
- Increase transfer capacity between the Plains and its neighbors, including a 175% increase in capacity with the Midwest and a 13-fold increase with Texas.
- Increased transmission is needed to reduce hourly price differences between the Plains and its neighbors.
Midwest
- Expand transmission infrastructure to ensure systems remain reliable when more than 40% renewable energy is incorporated into MISO.
- Increase transfer capacity between the Midwest and the Plains by 175% and between the Midwest and Southeast by 54%.
- Capacity expansion models suggest the most effective way to alleviate congestion between the Midwest and Delta regions is to increase transfer capacity between the Midwest and the Plains and between the Plains and the Delta — rather than between the Midwest and Delta directly.
Delta
- Improve transmission infrastructure to ensure systems are reliable when more than 40% of renewable is incorporated into MISO.
- Alleviate transfer capacity limits between the Midwest and Delta regions. Transfer limits between MISO Central and MISO South are biding most of the year, which can cause problems during extreme events in both regions.
- Increase transfer capacity between the Delta and Plains regions by 414% and between the Delta and Southeast regions by 86%.
Southeast
- Increase new transmission by 77% compared to 2020; existing utility plans for transmission development do not meet anticipated need.
- Increase transfer capacity between the Southeast by as much as and all its neighbors by as much as 10 GW to meet future load and generation growth.
Florida
- Increase transfer capacity between Florida and the Southeast by approximately 32% compared to the 2020 system.
Mid-Atlantic
- Relieve congestion constraints in the eastern portion of the Mid-Atlantic.
- Increase transfer capacity between the Mid-Atlantic and all its neighbors, including a 156% increase in transfer capacity with the Midwest compared to the 2020 system.
New York
- Increase transmission to improve access to low-cost generation, which will relive high prices in areas like Long Island.
- Increase transfer capacity between New York and both its neighbors by 2035, including a 122% increase in transfer capacity with the Mid-Atlantic and a 255% increase in transfer capacity with New England.
New England
- Offshore transmission can help integrate offshore wind generation without compromising reliability of the onshore transmission system.
- Increase transfer capacity with New York by 255% by 2035.
- Increase transfer capacity with Canada to meet future load and generation growth. This will also enable bidirectional flow of hydropower, wind, and solar.
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