It’s a gaping hole in most conversations about fuel: what do we do about liquid transportation fuels?

No matter how quickly we try to electrify our transportation sector, gasoline isn’t going away. Diesel isn’t going away. Jet fuel certainly isn’t going away. Even the most ambitious estimates set forth by the Energy Information Administration (EIA) in their Annual Energy Outlook indicate that liquid transportation fuel market penetration will remain well above 50% through 2050. 

Electric vehicle (EV) infrastructure is expensive, and much easier to install in cities and suburbs; rural communities especially will continue to rely on liquid transportation fuels. Furthermore, a third of the transportation fuel used in the United States goes to fuel heavy-duty applications. Think airplanes, trucks, large ships – these are not as easily electrified as a lightweight passenger car. Electric technology for these vehicles is limited and not available at scale.

​To be clear: I support electrification of the U.S.’s transportation space. What is happening with electric cars is revolutionary, and it will be good for the planet. More electric vehicles means fewer carbon emissions, and regardless of political leanings, I hope to live in a world where we can all agree that pollution is bad. In fact, I want renewable electricity widely available because it lowers the greenhouse gas (GHG) footprint of biofuel production plants, too. 

​​But EVs are not the be-all and end-all for the transportation space. We’ve invested billions over the years to develop advanced biofuels and other sources of renewable liquid fuels. Let’s make sure we are on track to decarbonize all the liquid fuels in our country, too.

US motor gasoline and diesel consumption (2000 - 2020), in million barrels/day.

Indeed, this investment in research and development has brought to fruition the possibility to replace whole gallons of diesel fuel, gasoline, and jet fuel. Rather than blending renewable fuels into these gallons, we are scaling “drop-in” replacements, a path that will lead to full replacement. This is a game-changer.

​However, the reality is that the most innovative renewable fuel sources available – those that reduce GHG emissions by 50% or more compared to a gasoline or diesel baseline – are cost competitive when the price of oil is high, but not when it is low. That is, they aren’t cost competitive unless we begin pricing the externalities associated with traditional energy sources. As good stewards of our human and environmental resources, it is our responsibility to make the economics for renewable fuels work.

​​That is exactly what Congress recognized when it first enacted the Renewable Fuel Standard (RFS) in 2005 and expanded it in 2007. The policy was ahead of the curve: it created standards for compliance that rewarded higher GHG emissions reductions. It envisioned a future where we could grow carbon feedstocks from starch, cellulose, and other agricultural resources that could be scaled. And scalability is king.

Sustainability means nothing if not aggregated – even the most incremental improvements make a difference when we are talking about every gallon of liquid transportation fuel in the U.S. market. And over the last few years, we’ve proved that food and fuel can be delivered together in this way. A soybean can deliver meal alongside oil, corn can be grown sustainably, and innovative agricultural practices enable us improve soil quality and sequester carbon in the soil.  Increased demand for protein for use in food drives availability of agriculturally based raw materials useful for making low carbon fuels. Starch is scalable. Cellulosic feedstocks like wood and municipal solid waste (MSW) are becoming scalable too.   ​

US liquid fuel components, by annual change

In addition to eliminating fossil-based emissions, we should begin to remove carbon dioxide from the atmosphere in excess of what is needed to displace fossil carbon. How can this be done? By using our immense agricultural and forestry resources properly. Carbon footprints and other sustainability measures can now be tracked through supply chains from growing or sourcing to burning of a fuel in an engine. The fossil footprint from liquid fuels can be eliminated, but it will take cooperation across agriculture and forestry where renewable carbon in generated; across electrical and natural gas generation. 

Today’s consumers demand more sustainable practices every day, extending to fuel as much as raw agricultural product. Modern farming practices enable us to capture carbon in the soil, and it is possible to sustainably harvest slash, or even trees, while capturing carbon dioxide in the biomass and soil in the forest. If we had incentives in place to reward these sustainable practices, we would see large offsets to fossil-based carbon. Done right, the agriculture and forestry sectors can be among the U.S.’s strongest allies in reducing GHG emissions.

In 2018, the U.S. transportation sector was responsible for a third of U.S. emissions. Air travel will grow 77% between 2018 and 2050 as the world continues to globalize and personal incomes continue to rise, projects the EIA. We need a way to fuel these airplanes sustainably and economically. Addressing climate change will necessitate comprehensive solutions in the transportation space. 

We’re all working toward the same goal: reducing GHG emissions to slow the effects of climate change. It’s a big elephant, though, and we’ll need a village of innovative technologies that can each take a bite if we ever hope to eat it.


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