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Transportation and Climate

Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) Tool

EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) is a full vehicle simulation tool which estimates the greenhouse gas (GHG) emissions from light-duty vehicle sources. It is a physics-based, forward-looking, full vehicle simulator, capable of simulating various vehicle types and powertrain technologies. Version 2.0 of the ALPHA model has been updated from the previous version to include more realistic vehicle behavior and now includes internal auditing of all energy flows in the model.

ALPHA is being used by EPA to inform the Midterm Evaluation of Light-duty Vehicle Standards for Model Years 2022-2025. The MTE will be conducted through a collaborative, data-driven, and transparent process. The documentation of ALPHA on this page is part of EPA’s commitment to transparency in the MTE process. ALPHA is an in-house vehicle simulation tool used by EPA, and is not intended to be a commercial product.

The ALPHA model shares an underlying structure with EPA's Greenhouse Gas Emissions Model (GEM) used for medium- and heavy-duty vehicle compliance calculations. ALPHA is under active development and the versions of the model presented below represent the state of the package at particular points in time.

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

ALPHA v2.0 Simulation Samples

EPA is using ALPHA simulation results to inform its on-going calibration of the Lumped Parameter Model (LPM), an EPA desktop computer application that estimates the effectiveness (CO2 Reduction) of various technology combinations. A subset of the numerous ALPHA simulation results being studied during the MTE process were identified as key simulations used to inform the calibration of the LPM.

  • ALPHA v2.0 Simulation Samples (ZIP) (4MB) This file contains a series of ALPHA V2.0 simulations (as of 2016.07.07) of the same type used to inform the calibration of the Lumped Parameter Model. Running this version of ALPHA requires Matlab/Simulink with StateFlow 2014a. For convenience, a plaintext form of the workspace for each ALPHA run is provided in an m-file format. Further details are in the readme.txt file.

ALPHA v2.0 Peer Review

EPA engaged ICF International to perform a peer review of the ALPHA Full Vehicle Simulation Model. This peer review process was carried out under EPA’s peer review guidelines. The entire model and all subsystems were unlocked for complete transparency. A number of independent subject matter experts provided reviews and comments on the methodologies used in the model.

  • ALPHA v2.0 Peer Review
    This file contains the ICF peer review report for ALPHA v 2.0 and will be available soon.

  • ALPHA v2.0 Peer Review (ZIP) (1.14MB)
    This file contains the files provided to peer reviewers for ALPHA v2.0 (as of 2016.05.05). Running the peer reviewed version of ALPHA requires Matlab/Simulink with StateFlow 2014a. Further details are in the readme.txt file.

Publications Concerning ALPHA v2.0

Throughout the MTE process, EPA’s goal is to publish as much of our research as possible in peer-reviewed technical papers and journals. These publications describe in more detail the development and use of the ALPHA model.

Overview of Testing and Integration with Modeling

Through its National Center for Advanced Technology (NCAT), EPA has integrated benchmarking and modeling activities to ensure robust data.

Engine Mapping Process Documents

Integrating test data and modeling results for engines into the ALPHA model requires a process for translating test results into a full map representing all phases of engine operation. The following documents explain the process for creating ALPHA engine maps for key engine packages.

ALPHA v1.0

The initial version of ALPHA, used for off-cycle technology evaluations, is provided for historical purposes. The software is a freely-distributed, desktop computer based application, built on MATLAB/Simulink. EPA is no longer using this version of ALPHA.

The downloadable installation file below (in a zip format) contains the ALPHA v1.0 tool. The model documentation provides details on how to launch and run the simulation tool.

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
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