8. Zero Carbon Vehicles

Transportation accounts for about 30% of GHG emissions in the United States, and more than half of that comes from passenger vehicles. Decarbonizing transportation is as challenging as decarbonizing electricity, but in different ways. Essentially, vehicles from aircraft to automobiles that currently run on liquid fossil fuels will have to find another power source that doesn’t emit GHG. Unlike stationary electrical power plants, vehicles are mobile and thus require zero carbon power sources that are robust, light weight, portable, and quickly renewed or refilled. The current choices are electrically-powered vehicles that run on rechargeable batteries or internal combustion engines that use liquid or gaseous biofuels with net zero carbon emissions. Possible advanced options for electrical power sources include chemical fuel cells, and hydrogen is under consideration as a non-carbon fuel for internal combustion engines. Transportation also can be decarbonized through initiatives like mass transit trains powered by net zero electricity and cities that reduce automobile use by being more pedestrian and bicycle-friendly. As with most things in life, none of these are perfect and they all have their advantages and disadvantages. Given the potential severity of the climate crisis, however, an “all of the above” strategy for zero carbon vehicles is warranted.