Transmission Impossible? Prospects for Decarbonizing the US Grid

Encouraged by the declining cost of grid-scale renewables, recent analyses conclude that the United States could reach net zero carbon dioxide emissions by 2050 at relatively low cost using currently available technologies. While the cost of renewable generation has declined dramatically, integrating these renewables would require a large expansion in transmission to deliver that power. Already there is growing evidence that the United States has insufficient transmission capacity, and current levels of annual investment are well below what would be required for a renewables-dominated system. We describe a variety of challenges that make it difficult to build new transmission and potential policy responses to mitigate them, as well as possible substitutes for some new transmission capacity.