It is essential to cost-effective decarbonization and resilience
In the shift to a low-carbon economy, cars and many industrial sectors will increasingly rely on electricity. The additional demand and the shift to low- and no-carbon generation such as wind, solar, nuclear, and geothermal, combined with battery storage, will require a similar or greater increase in transmission capacity. Though distributed energy resources will meet some of this demand, many studies find that transmission is critical to achieving net zero goals in a cost-effective manner.
Decarbonization pathways may require two or three times more transmission capacity than the US has today. A 2016 study by researchers with the National Oceanic and Atmospheric Administration called for a high-voltage direct current (HVDC) transmission network spanning the country as part of the lowest-cost solution for reducing emissions by 80 percent by 2030. The recent Princeton Net-Zero America study found that transmission capacity may need to triple, expanding traditional alternating current lines and adding interstate HVDC. Though the levels of expansion and technology options vary, transmission consistently plays an important role in decarbonization pathways across analyses by federal agencies, universities, and industry groups.
Expanding transmission capacity, whether through existing rights-of-way or building new lines, will allow transmission projects to connect physical resources between regions. The figure below, from the National Renewable Energy Laboratory’s (NREL) SEAMS study, illustrates how our renewable resources are spread across the country. The highest-efficiency wind and solar resources are found in the Great Plains and Southwest. These resource-rich areas depend on transmission capacity to connect with load centers in the Midwest and along both coasts. Decarbonizing the electric grid will require significant annual growth in renewable energy resources. Transmission must be coupled with the changing resource mix to balance the supply and demand across time and weather changes.
As demonstrated by a 2020 MIT study, state-level policies such as renewable portfolio standards and regional transmission arrangements will fail to realize the benefits of time-shifting renewable energy. Building new inter-regional transmission across the nation’s separate electric grids would be the cheapest option, reducing the cost per megawatt-hour ($/MWH) of zero-carbon electricity by almost 50 percent compared to regionally constrained approaches.
Transmission provides geographic diversity, allowing each region to share its resources. Decarbonization pathways in the studies above indicate nuclear, hydropower, and geothermal generation will also benefit from transmission. Transmission additionally serves as a buffer for regions across weather variability. A heat wave or cold snap can cause demand spikes that remote resources can support. Early analysis of the cold snap of February 2021 shows that the Eastern U.S. and the West Coast both had available capacity that could have been dispatched to decrease the rolling blackouts in the Great Plains — had the transmission lines existed.
More regionalized pathways are more expensive pathways. Even more important to consider, these regional solutions still require a scale of siting for generation that will face barriers. The current difficulties of building transmission mean that we must face the issues and fix them. Any alternative is still going to be challenging and even more expensive.