As modeled by NREL, wind and solar energy would provide 60%–80% of generation in the least-costly electricity mix in 2035. The overall generation capacity would grow to roughly three times the 2020 level by 2035—including a combined 2 TW (terawatts) of wind and solar.

To achieve those levels would require an additional 40–90 GW of solar on the grid per year and 70–150 GW of wind per year by the end of the decade, said NREL. That is more than four times the current annual deployment levels for each technology.

If challenges arise around siting and land use restrictions, researchers said nuclear power capacity would help make up the difference. However, nuclear resources would need to more than double the current installed capacity.

Across four scenarios modeled by NREL, 5–8 GW of new hydropower and 3–5 GW of new geothermal would also be deployed by 2035. Energy storage between 2–12 hours of capacity would also increase, with 120–350 GW of capacity deployed by 2035.

NREL also said seasonal storage capacity in 2035 could range from about 100 to 680 GW. Seasonal storage is important when clean electricity makes up about 80%–95% of generation and a mismatch exists between variable renewable supply and demand.

Seasonal storage is represented in the study as hydrogen-fueled combustion turbines, but it could also include other emerging technologies.

In all scenarios, significant transmission is also added in many locations, mostly to deliver energy from wind-rich regions to load centers in the eastern U.S. As modeled, the total transmission capacity in 2035 is one to almost three times the current capacity. That would require between 1,400 and 10,100 miles of new high-capacity lines per year, assuming new construction were to start in 2026.

In all modeled scenarios, NREL found that the health and climate benefits associated with fewer emissions exceed the power system costs to get to 100% clean electricity.

To decarbonize the grid by 2035, researchers said the total system costs between 2023 and 2035 would range from $330 billion to $740 billion. The scenarios with the highest cost modeled by NREL included restrictions on new transmission and other infrastructure development.

In the scenario with the highest cost, the amount of wind to be delivered to large population centers would be constrained, with more storage and nuclear generation deployed.

Overall, researchers said that as a result of the emission reductions and better air quality, up to 130,000 premature deaths would be avoided in the coming decades, saving $390 billion to $400 billion. Those totals would likely exceed the cost of decarbonizing the electric grid.

NREL said that when factoring in the avoided cost of damage from the impacts of climate change, a net-zero grid could save more than an additional $1.2 trillion.

“The benefits of a zero-carbon grid outweigh the costs in each of the more than 100 scenarios modeled in this study, and accelerated cost declines for renewable and clean energy technologies could lead to even larger benefits,” said Patrick Brown, another co-author.

NREL identified four key challenges that must be addressed in the next decade, through further research and other societal efforts, to enable full power sector decarbonization.

Dramatic acceleration of electrification

Electrification of some end-use energy services in the buildings, transportation, and industrial sectors is a key strategy for decarbonizing those sectors. NREL said increased electrification also increases overall electricity demand and the scale of the power system that needs to be decarbonized.

New energy infrastructure

This would include siting and interconnecting new renewables and storage at a rate three to six times greater than recent levels, which would set the stage for doubling or tripling the capacity of transmission, upgrading the distribution system, building new pipelines and storage for hydrogen and CO2, and/or deploying nuclear and carbon management technologies. The recently-enacted Inflation Reduction Act could jumpstart the deployment needed by making it more cost-effective.

Expanded clean energy manufacturing

The unprecedented deployment rates would require growth in raw materials, manufacturing facilities, and a trained workforce throughout clean energy supply chains. NREL said further analysis is needed to understand how to rapidly scale up manufacturing.

Continued R&D

NREL said technologies currently being deployed widely can provide most of U.S. electricity by 2035 in a deeply decarbonized power sector, but achieving a net-zero electricity sector at the lowest cost will take advances in research & development into emerging technologies—particularly to overcome the last 10% to full decarbonization.

NREL said getting from a 90% clean grid to full decarbonization could be accelerated by developing large-scale, commercialized deployment solutions for clean hydrogen and other low-carbon fuels, advanced nuclear, price-responsive demand response, carbon capture and storage, direct air capture, and advanced grid controls.

The new report follows the enactment of the Inflation Reduction Act (IRA), which is estimated to reduce economy-wide emissions in the U.S. to 40% below 2005 levels by 2030. Initial analysis from the U.S. Department of Energy (DOE) estimates that grid emissions could decline to 68%–78% below 2005 levels by 2030.

NREL said the longer-term implications of the new law are uncertain, but they likely will not get the U.S. all the way to 100% carbon-free electricity by 2035.

None of the scenarios presented in NREL’s report include energy provisions in the IRA or the previously enacted infrastructure law, but researchers said their inclusion is not expected to significantly alter the 100% systems explored—and the study’s insights on the implications of achieving net-zero power sector decarbonization by 2035 are expected to still apply.

NREL’s study was funded by DOE. For more, here is a closer look.