Research and development, manufacturing, and infrastructure investment decisions over the next decade will determine how the United States achieves a 100% clean electricity system by 2035, say the authors of a new report that finds multiple pathways to hit the target.
“There is no one single solution to transitioning the power sector to renewable and clean energy technologies,” said Paul Denholm, principal investigator and lead author of the study by the U.S. National Renewable Energy Laboratory (NREL). “There are several key challenges that we still need to understand and will need to be addressed over the next decade to enable the speed and scale of deployment necessary to achieve the 2035 goal.”
The study used NREL’s Regional Energy Deployment System (ReEDS) model, which helped the researchers “explore how different factors—like siting constraints or evolving technology cost reductions—might influence the ability to accelerate renewable and clean energy technology deployment,” said co-author and NREL analyst Brian Sergi.
Although the report’s release closely follows the recent signing of the U.S. Inflation Reduction Act (IRA), which will work alongside the Bipartisan Infrastructure Law to greatly expand U.S. clean energy infrastructure, the research took place before the new laws and does not reflect their influence on the different scenarios.
Even so, NREL found multiple pathways for the U.S. to reach the 2035 target in which “benefits exceed costs”, using different combinations of technology mix, policy changes, and infrastructure investments.
All the scenarios deploy new clean energy technologies “at an unprecedented scale and rate to achieve 100% clean electricity by 2035,” writes NREL. In the least-cost 2035 electricity mix, wind and solar energy provide 60% to 80% of generation, and overall generation capacity roughly triples between 2020 and 2035, including a combined two terawatts (two million megawatts) of wind and solar.
The scenarios also deploy five to eight gigawatts of new hydropower, three to five gigawatts of new geothermal capacity, and 120 to 135 gigawatts of diurnal energy storage. NREL says seasonal storage becomes important when about 80% to 95% of generation is from clean electricity and there is a multiday-to-seasonal mismatch of variable renewable supply and demand. The study only considered clean hydrogen-fueled combustion turbines for seasonal storage, but a variety of emerging technologies could also be used. All scenarios will also require a major expansion of transmission capacity.
NREL outlines four key hurdles to decarbonizing the power sector.
• End use energy services in buildings, transportation, and industrial sectors will need to electrify, thereby increasing strain on the electricity system.
• New energy infrastructure will have to be installed very rapidly—at three to six times the current pace—although the IRA could help speed up deployment.
• But that will put a strain current supply chain, work force, and manufacturing capacity, all of which will need to ramp up effectively.
• The report calls for continuing research and development on the emerging technologies that will be crucial to achieving the final 10% of the transition to carbon-free electricity, due to rising costs as systems become more decarbonized.
“Failing to achieve any of the ambitious tasks outlined in the study will likely make it harder to realize a net-zero grid by 2035,” said NREL analyst and study co-author Trieu Mai.