Technical Limitations

This website explains detailed assumptions that are essential to appropriate interpretation of the data. We recommend familiarizing yourself with the website documentation before using Annual Technology Baseline (ATB) data. The following summary of technical limitations does not substitute for the more complete documentation. Contact us if you have questions. 

The purpose of the Transportation ATB is to provide estimates for Base Year (2022) and future year projections. The vehicle assumptions represent time-series trajectories at three levels of technical innovation. The fuels assumptions show snapshots in time for current market and future modeled fuels. The assumptions are intended to be useful to analysts, including modelers interested in representing technical innovation.

The ATB strives to provide future projections grounded in science- and engineering-based technology analysis. References are provided that document the available scientific basis. However, we note the following limitations: 

• The ATB may be missing important possible future scenarios and technology options. We welcome feedback on topics for future updates.
• Because fuels assumptions are snapshots in time, emissions assumptions will not reflect expected emissions at each time point.
• The assumptions for fuel costs and fuel emissions may not align. Some fuel costs lack techno-economic references, and some fuel pathways use different techno-economic sources for costs and emissions.
• For technologies that are not yet deployed at scale, especially medium- and heavy-duty battery electric vehicles and fuel cell electric vehicles, we have attempted to convey the uncertainty in recharging and refueling costs—but these remain challenging topics for projections.