Reducing Greenhouse Gas Emissions from the Transportation Sector

The transportation sector is entirely dependent on petroleum-based fuels today and is one of the major sources of greenhouse gas (GHG) emissions.  While many focus on passenger cars and light-trucks which make up the majority of transportation emissions, the transportation sector is actually quite varied, consisting of a wide diversity of vehicles and applications.  The challenge of GHG emissions reduction in transportation relates to this diversity.  This analysis addresses all sub-sectors of transportation including light-duty vehicles (passenger cars and trucks), heavy-duty vehicles (buses and long- and short-haul trucks), aviation, rail, marine and off-road.   

The goal of reducing emissions from transportation involves pulling three “levers”: addressing travel demand, vehicle efficiency and fuel carbon (also known as the three legged-stool).  Generally, travel demands are projected to increase in the future, both because of population growth but also per capita increases in demand for personal mobility and goods movement. Vehicle efficiency is critical for reducing energy use per vehicle.  There is significant potential in all subsectors to reduce energy use per mile of travel by 50% or more from today’s levels.  Reductions in fuel carbon can come about primarily by switching to new lower-carbon fuels.  Some, such as biofuels, may be implemented with small changes to vehicles and delivery and refueling infrastructure, while others such as hydrogen or electricity, require significant changes to vehicles and/or infrastructure.  Vehicles in some sub-sectors, such as light-duty, buses and trains can be electrified, powered by wire, batteries, or fuel cells.  Others, such as long-haul trucking, aviation and marine, will likely continue to rely on combustion of liquid fuels.  

This talk will review the opportunities to reduce emission in the various sub-sectors via these levers and where the challenges and barriers exist and present scenarios for reduced energy use and fuel substitution by 2050.