On Friday, November 17, world leaders concluded the 23rd Conference of the Parties (COP) in Bonn, Germany.  While the United States federal government has largely disengaged from the process, leaders from every other nation met to hammer out details of how countries will meet the previously agreed upon target of keeping warming below 2 degrees Celsius.

Out of Bonn, there is recognition that most countries are not going to meet the 2 degree target agreed upon at the historic 2015 Paris Climate Accord, unless more stringent emission reductions are undertaken by individual nations. Global leaders will need to decide on and implement deep decarbonization strategies for every major sector – energy, transportation, agriculture and forestry, buildings, and industry.  And the longer we dally, the more difficult the task becomes.

The transportation sector will be particularly difficult to decarbonize – due to its diffuse nature and use of high-density, easily transportable liquid fuels. Additionally, vehicles and other forms of transportation (aviation, marine) are durable and long-lasting, making any progress on decarbonization a slow process.

According to the UN, transport is the second biggest source of energy-related greenhouse gas emissions, and transport’s share of emissions will continue to increase unless meaningful action is taken. So, how will the transportation sector effectively transition to a low or zero-emissions scenario? 

Rather than betting on one technology over another – business leaders and policy makers need to get serious about the necessary contributions that low-carbon biofuels, electrification and efficiency will each need to provide in the transportation sector. Only through using these technologies together in a complementary fashion will countries have the ability to cost-effectively make the necessary emission cuts to the transportation sector.  

Today and in the near future, biofuels such as ethanol and biogas should continue to be a leading edge in transportation decarbonization – particularly in the light duty fleet. In the U.S., the majority of light duty passenger vehicles can accept blends of 15 percent ethanol (E15). But higher biofuel blends are available, and are required, if we are to address transportation sector emissions immediately.

Higher biofuel blends (such as E25) can enable highly efficient, smaller engines. Additionally, in co-deploying higher biofuel blends, highly efficient internal combustion engines, and hybridization – we can immediately and dramatically reduce the volume of petroleum used in passenger vehicles.  Other biofuels, such as renewable natural gas, can also be an immediate wedge, particularly in fleet vehicles such as delivery trucks and buses.

Looking a bit further ahead, in the United States, the popular classes of crossover SUVs and larger trucks, which are presently difficult to electrify, could continue to be an outlet for biofuels while the fleet of smaller passenger vehicles transition towards electrification.  But looking forward several decades, electric vehicles will need to be the primary source of passenger transportation, in order to meet climate targets. Biofuels could still play a role in the future, but primarily as range extenders to electric vehicles.

Over the next several decades, biofuels will play an important role in the heavy duty transportation sector.  Despite Tesla’s recent splashy announcement of its electric semi-truck, liquid fuels will be required for the foreseeable future by aviation and shipping. This is where efficiency and low-carbon renewable biofuels should be deployed to reduce emissions to the greatest extent possible.  The aviation sector is currently scrambling to reduce the sector’s growing emissions – and this primarily includes investments in low-carbon biofuels and efficiency measures. Additional shifts in transportation, like ridesharing, autonomous vehicles, and mass transit will also play an important role in increasing the overall efficiency of the transportation sector, particularly in densely populated areas.

Despite rapid technological progress of renewable technologies, the somber mood in Bonn underscores the uncomfortable truth – time is running out to meet the requirements of a livable planet.  Leaders in the transportation sector, policy makers and stakeholders need to come together and put aside partisan infighting over favored technologies to evaluate common-sense measures available to drastically, and quickly, reduce transportation sector emissions.