#Version History

Policy and technology updates throughout the model, including data center load; this version corresponds to the LCRI Net-Zero Scenarios 2.0 report and the open-source version of US-REGEN.

Changes

• Added and updated incentives from the Inflation Reduction Act (IRA) across a wide range clean energy technologies in the electric and non-electric sectors.
• Updated scenarios for data center load.
• Updated technology and resource assumptions for hydrogen production and infrastructure, CO₂ storage, and bioenergy.
• Enhanced and updated representation of energy-related water use and criteria air pollutant emissions.
• Integration of electric and fuel supply models into a single joint optimization program.

Major enhancements to support the Low-Carbon Resources Initiative in 2021, including the creation of a fuels model within US-REGEN.

Changes

• Fuels model was added that describes the supply and conversion of primary energy into delivered fuels supplied to the electric and end-use models. It includes several technologies for conversion, blending, and synthesis of fuels, including petroleum refining, biomass to liquids or gas, blending of renewable natural gas and hydrogen into existing pipeline infrastructure, ammonia production, and fuel synthesis.
• Carbon management enhancements include updates to the transport and storage of captured carbon dioxide, and the addition of direct air capture technologies and natural climate solutions as potential carbon sinks.
• Updated and expanded hydrogen production technologies include 4 types of electrolysis in addition to steam-methane reforming, and coal/biomass gasification.
• Updated biomass supply assumptions.
• Expanded transportation technologies (vehicle classes and types) and their associated cost/performance assumptions, including the addition of hydrogen fuel cell vehicles.

January 2020 documentation update, describing the model's structure at the end of 2019.

Changes

• Electric model was substantially revamped, with a greater focus on hourly dispatch to support storage modeling, reserve margins added as a default option, and the option to use sub-state data now included, where data is available.
• CO₂ storage and transport costs were added explicitly to the modeling of carbon capture and storage technologies.
• Additional state level policies were added to maintain coverage of renewable portfolio and clean energy standards, state clean energy targets, and other technology carveouts for solar and offshore wind.
• Improvements were made to the end-use model, incorporating insights from the state supplemental projects.

Describes the model's structure as of first quarter 2018 and introduces an end-use model to improve the characterization of energy demand.

Changes

• Technology cost updates were applied to solar PV, onshore wind, and biomass with carbon capture and storage.
• Unit database was updated to be current as of August 2016, and the base year data from the EIA was updated to the latest available.
• A new existing inter-state transmission dataset was developed using NREL data.
• Production and Investment Tax Credit representations were adjusted following new legislation, and the state renewable portfolio standards were updated to be current as of December 2016. The biggest change was an implementation of the U.S. EPA's final regulations on CO₂ emissions from existing fossil units, collectively known as the Clean Power Plan. Updates here included the ability to model state-by-state rate- or mass-based constraints, and a representation of the renewable set-aside allowance allocation program included under the Clean Power Plan.
• End-use model was developed in 2016-2017 and integrated with the electric sector model to dynamically capture the evolution of demand for electricity and other end-use fuels. It has temporarily replaced the computable general equilibrium (CGE) model used in previous versions to represent demand-side feedbacks. Although the end-use model describes trade-offs between technologies and fuels in much greater detail than the CGE model, it does not incorporate macroeconomic feedbacks, for example service demand responses to increased energy prices. Future model versions will re-introduce the CGE structure as an additional layer to capture these feedbacks.

Describes the unit commitment model, its capabilities, and its relation to the dynamic version of US-REGEN.

Changes

• A stand-alone unit commitment version of US-REGEN has been developed to better understand the short-run costs and engineering challenges of operating the electricity generation capacity mixes suggested by the full US-REGEN dynamic model.
• This unit commitment model investigates power system operations on an hourly level for each unit over an annual time horizon and includes constraints related to ramping, turndown limits, and startups, which are not traditionally captured in reduced-form representations of dispatch.
• Given the significance of transmission and trade as flexibility resources in electricity markets, a novel feature of the model is its endogenous treatment of imports and exports across regions.

Describes the model's structure as of fourth quarter 2014.

First public release that describes the US-REGEN model, the methodology and theory that underlie it, and the construction of the associated datasets that inform the model.