A group of grid companies released a report re-enforcing a long-standing assertion that achieving carbon reduction goals depends on long-haul, high-voltage transmission lines to carry renewable energy to load centers.

The report says that state and local policies, however, discourage transmission development due to siting and permitting processes that slow and even stop projects. States prefer the optics of locally sourced renewable energy even when less expensive renewable power could be imported. The report was prepared by the ScottMadden Inc. consulting firm for the WIRES coalition.

The report outlines what it says are four recent developments that warrant consideration given their impacts on the bulk power system and transmission: the changing energy mix, deployment of distributed energy resources and energy storage, aspirations for beneficial electrification such as electric vehicles, and ongoing interest in renewable and zero emissions resources.

The report argues that transmission can, and should, play a "significant role in addressing the challenges raised by these factors." It says that as more states, utilities, and other companies mandate or commit to clean energy goals, it will not be possible to meet those targets without additional transmission. "Similarly, the current transmission system will need expansion and hardening if it is to withstand, reduce, and recover quickly from high-impact events affecting the bulk power system."

In the current environment, the report says, transmission is increasingly difficult to build. "With greenfield transmission projects taking 10 years or longer to be put into service, decisions regarding any transmission projects required to meet renewables integration and resilience concerns must be made quickly."

The report details region-by-region opportunities for long-haul transmission projects to move renewable energy to load centers. It also criticizes what it calls the failure of the Federal Energy Regulatory Commission's Order 1000 to spark construction of more interregional power lines to move wind and solar power across multiple states.

The 2011 order called for more interregional planning but stopped short of requiring it. Encouragement without a mandate backing it up wasn't enough to overcome state opposition to big projects.

The report calls on FERC to create financial incentives for transmission to support renewable energy and strengthen grid networks against natural disasters and cyberattacks.

"Until a forcing function requires these regions to develop a methodology that facilitates largely public policy projects, the hope of interregional transmission meeting national needs for transmission will remain elusive," the report says.

Transmission developers can't look for unified backing from green energy partisans. "Environmental interests stack up on both sides of the transmission development debate," the report says.

Using data from the Energy Department's Lawrence Berkeley National Laboratory and the National Renewable Energy Laboratory, the report maps U.S. regions where surplus wind and solar power are likely to exceed state-set renewable energy targets.