1.1 Summary
The US Regional Economy, Greenhouse Gas, and Energy Model (US-REGEN) is an energy-economy model developed and maintained by the Electric Power Research Institute (EPRI). It combines a detailed dispatch and capacity expansion model of the United States electric sector with a technologically detailed consumer choice model of end-use service and energy demand. The two models are solved iteratively to convergence, allowing analysis of policy impacts on the electric sector taking into account electricity demand responses, and conversely allowing analysis of how end-use energy policies and technological improvements impact electric demand and load shapes. The electric sector model can also be run separately with higher regional and temporal resolution, or for a single year with hourly resolution and unit commitment constraints. This makes US-REGEN capable of modeling a wide range of environmental and energy policies in both the electric and non-electric sectors.
US-REGEN is a regional model of the United States. It can consider multiple sub-regions of the continental U.S., to account for differences in resource endowments, energy demand, costs, policies, and policy impacts, as well as transmission of electricity. By default, the model uses 16 sub-regions, each an aggregation of states, but with the datasets currently included, can be configured to consider any arbitrary aggregation of the lower 48 states plus the eleven New York Independent System Operator (NYISO) zones within New York state. The electric model can be extended to include additional sub-state detail for other states based on the boundaries of independent system operators (ISOs) and regional transmission operators (RTOs). An extension of the model to include Canadian provinces is under development. Figure 1‑1 shows a map of the default sub-regions in the model.[1] US-REGEN is an inter-temporal optimization model. By default it solves in five year time-steps from 2015 through 2050, but can be configured to use other time-steps and base years.
The electric sector component of US-REGEN is a detailed generation planning model. In each time step, the model makes decisions about capacity (e.g. new investments, retrofits, and/or retirements) and dispatch to meet energy demand for both generation and inter-region transmission. It uses a bottom-up representation of power generation capacity and dispatch across a range of intra-annual time segments. It models transmission capacity between regions and requires that generation and load plus net exports and line losses balance in each time segment and for each region. In electric sector only mode, the model is capable of representing all lower 48 states as well as various intra-state zones as separate regions.
The end-use component of US-REGEN represents trade-offs between end-use technologies and fuels for a wide range of disaggregated sectors and activities with economy-wide coverage. The model includes structural detail across several dimensions relevant for fuel and technology choice, such as building size, type, and vintage, climate zone and location, and vehicle ownership and driving intensity. Within each structural category, service demand may be met with a range of options, characterized as combinations of fuels and technologies. The model evaluates the total cost of each option in each new vintage based on assumed technology cost and performance, fuel prices, structural attributes of service demand, and non-economic factors. The resulting allocation across the options is based on a logit model translating relative costs to equilibrium market shares, with a lagged process to simulate a gradual transition toward the model's calculated equilibrium shares. The model then calculates annual and hourly fuel use by region as a function of the resulting mix of end-use technologies. The electricity data outputs of this model are inputs to the electric sector model.
The electric sector model is formulated as a linear programming problem. The end use model is a set of modules representing different sectors, which are formulated using a mix of logit simulation and linear programming methods. Both are implemented within the GAMS software environment.
The two models comprising US-REGEN use several primary sources to calibrate to observed data:
- Economic data sourced from the IMPLAN database
- Energy data from the Energy Information Administration (EIA) of the U.S. Department of Energy
- Gridded weather data from the National Aeronautics and Space Administration (NASA)
- Household travel survey data from the U.S. Department of Transportation Federal Highway Administration
- U.S. generation fleet and emissions data from ABB Energy Velocity (formerly Ventyx)
- The National Emissions Inventory (NEI)
- Technology cost and performance data from the Electric Power Research Institute (EPRI)
- A variety of other sources providing detail on economic growth, policy, and biomass, among others
Further details on data sources are provided in the subsequent chapters and in Appendix A. Chapter 2 of this document covers the electric sector model, and Chapter 3 covers the end-use model. Note that this documentation is not intended to convey results and analysis arising from use of US-REGEN, although some limited results are shown to demonstrate how the model works.[2]
In defining the regions of the integrated model, there is necessarily a tradeoff between optimally representing the economy, where data is typically available along state lines, and optimally representing the U.S. electricity sector, the internal boundaries of which frequently cross state boundaries. ↩︎
Reports and journal articles based on US-REGEN results are available for download from https://eea.epri.com/usregenopen in new window ↩︎