A Transformative Climate Action Framework: Putting People at the Center of our Nation’s Clean Energy Transition

The document details a modeling framework combining EnergyPATHWAYS (EP) for demand-side stock accounting and the Regional Investment and Operations (RIO) model for supply-side least-cost optimization. It outlines nine scenarios for the U.S. energy transition, including a 'Zero CO2 2050' case and various electric vehicle (EV) adoption speeds. The methodology emphasizes high temporal and spatial resolution, co-optimizing electricity and fuel systems to meet economy-wide emissions constraints.

• The modeling framework utilizes two primary tools: EnergyPATHWAYS (EP), a bottom-up stock accounting model for final-energy demand across 64 subsectors, and the Regional Investment and Operations (RIO) model, a linear programming model that optimizes least-cost supply-side pathways.
• The 'Zero CO2 2050' scenario targets a 46.5% reduction in CO2 emissions below 2005 levels by 2030, reaching zero CO2 emissions by 2050, with a cumulative CO2 budget of 77 GT for the 2020-2050 period.
• The RIO model is distinguished by its ability to co-optimize the fuels and electricity sectors, allowing for the analysis of biomass allocation, carbon capture site competition, and the use of clean drop-in fuels for electricity generators.
• To manage computational runtime while maintaining accuracy, RIO uses a clustering algorithm to select 40 representative 'sample days' from 8,760 hourly profiles to represent a full historical weather year.
• The analysis incorporates specific supply-side assumptions for renewable energy, including rooftop and distributed PV increasing to 500 GW by 2050 and offshore wind reaching 55 GW by 2040.
• The framework evaluates different vehicle electrification trajectories, ranging from an 'Accelerated EV' case (100% ZEV sales for all vehicle types by 2035) to a '10 year+ EV delay' case (100% ZEV sales for light-duty vehicles by 2045).
• Reliability in high-renewable systems is modeled by enforcing a planning reserve requirement in every hour, accounting for the risk that renewable output may be lower than expected.

APA

Union of Concerned Scientists (2021). A Transformative Climate Action Framework: Putting People at the Center of our Nation’s Clean Energy Transition. https://www.ucs.org/sites/default/files/2021-07/TechAppendix_Clean_Energy_TransformationJuly2021.pdf

Chicago

Union of Concerned Scientists. A Transformative Climate Action Framework: Putting People at the Center of our Nation’s Clean Energy Transition. 2021. https://www.ucs.org/sites/default/files/2021-07/TechAppendix_Clean_Energy_TransformationJuly2021.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=A Transformative Climate Action Framework: Putting People at the Center of our Nation’s Clean Energy Transition |date=July 2021 |url=https://www.ucs.org/sites/default/files/2021-07/TechAppendix_Clean_Energy_TransformationJuly2021.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2021transformative, author = {{Union of Concerned Scientists}}, title = {{A Transformative Climate Action Framework: Putting People at the Center of our Nation’s Clean Energy Transition}}, institution = {Union of Concerned Scientists}, year = {2021}, month = jul, url = {https://www.ucs.org/sites/default/files/2021-07/TechAppendix_Clean_Energy_TransformationJuly2021.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }