Closing the Transportation Emissions Gap with Clean Fuels

Federal and state policies adopted over the past two decades have done a great deal to bend the curve of greenhouse gas (GHG) emissions from the US transportation sector. However, with 1.6 billion tons of CO2-equivalent projected to come from the transportation sector in 2030, we are still a long way from being on track to net-zero emissions by 2050, or from reducing transportation-related pollutants like NOx, particulate matter, and ozone, which disproportionately impact communities of color and low-income communities.

To achieve economy-wide net-zero emissions, we find that, in the transportation sector, a portfolio of strategies is the lowest cost and most likely to succeed. While efficiency improvements and vehicle electrification can cut transport emissions by up to two-thirds by 2050, low-GHG liquid fuels are needed to fill the remaining gap and achieve net-zero emissions in the transportation sector by mid-century.

Transportation is the largest source of GHG emissions in the US, accounting for 33% of the economy-wide total in 2019. While transport emissions declined 6% between 2005 and 2019, the majority of reductions have come from the passenger vehicle fleet (light-duty vehicles). Between 2005 and 2019, emissions from freight vehicles rose 5%, and aviation emissions rose by 14%.

Achieving net-zero emissions in the transportation sector will require aggressive federal policies across decarbonization pathways. Given future demand for transportation fuel, the US needs policies that promote development and wide-spread deployment of clean fuel, alongside electrification and efficiency measures. Clean fuel policies should focus on the comprehensive impacts—providing the largest incentives for the highest performing fuels across attributes and ensuring that deep decarbonization can be achieved across all modes of transportation.