Embracing Alcohol-based Fuels as the Key to Decarbonizing Long-Haul Trucking

by Peter Sopher (Clean Energy Ventures/Biofuels Digest) ... BloombergNEF forecast shows that the 2040 market penetration of these EVs remains a relatively small proportion of the overall fleet, especially for heavy commercial vehicles. To meet our greenhouse gas mitigation goals and impending state and national emissions regulations, we need new solutions to road and other highly polluting segments of the transportation sector – air, ocean, and rail transport, for example – where economic and performance traction of clean fuels are critically lagging.

The challenge is the ideal engine for a long-haul truck is one that minimizes weight, as well as refueling time and cost for cross-country trips, while maximizing torque and other performance measures.

For economic long-haul trucking, liquid fuels are still the best option at this point, but traditional diesel carries a high climate cost in terms of emissions, not to mention NO_x and particulates. The clean fuels that best fit long-haul trucking applications are alcohol-based ones including bioethanol and methanol, both of which pose less of an environmental impact compared to petroleum-based diesel. Major engine manufacturers are beginning to invest in new technologies to decouple diesel fuel from the diesel engine, such as diesel-style engines that can be powered by alcohol-based fuels, which require no sacrifice in performance or cost and comfortably meets the strictest NO_x, particulates and CO₂ emissions standards. Technologies like these are expected to be commercially available within five years, bringing the same benefits of diesel-fueled trucks in terms of optimized weight and the frequency, duration, and cost of refueling.

Another consideration for the future of long-haul trucking is the infrastructure, where the framework for climate-friendly alcohol-based fuels is far more developed than that of other clean alternatives like electrification or hydrogen. Depending on how it’s evaluated, U.S. ethanol production is 25 to 50 percent that of diesel; 17 billion gallons/year of ethanol is produced (an energy equivalent of 11 billion gallons/year of diesel) compared to 40+ billion gallons/year for diesel, so the global commodity precursors for alcohol-based fuels are readily available. Furthermore, many fleet operators own the refueling infrastructure used by long-haul trucks, and climate-friendly alcohol-based fuels like ethanol are easily transportable and can be stored in conventional storage tanks currently used for gasoline.

Similarly, hydrogen brings major challenges as well. Transporting gaseous fuels is no small task, a key reason why the adoption of natural gas-fueled buses and trucks has been so disappointing even with extremely low natural gas prices on a dollars per gallon equivalent basis. The build-out of infrastructure for hydrogen transport is in a nascent phase and will require continued, substantial momentum from corporations and local and national governments around the world to develop in a robust manner over the coming decades, with competition from stationary hydrogen storage and use of green hydrogen in industrial and chemical applications.

And speed matters for the climate fight – we can’t wait decades for electrification and hydrogen-based technologies to be fully viable alternatives; we have to start implementing innovative technologies that can make a difference sooner. Climate-friendly alcohol-based fuels have as clean (or cleaner) emissions profiles for the medium-term horizon than electricity and hydrogen. According to Argonne National Labs’ Greenhouse Gas, Regulated Emissions, and Energy Use in Transportation Model (GREET), there are significant life-cycle CO₂ reductions by transitioning from petroleum diesel to corn-based ethanol (39%), sugarcane-based ethanol (71%), corn stover ethanol (89%), flare gas methanol (86%), and biomass (94%). As sustainable harvesting and renewable power increasingly penetrate society, these emissions reduction percentages will see dramatic increases to 90%+ in the future.

It is also a naïve oversimplification to insinuate that electricity, alcohol-based fuels, and hydrogen are completely clean today, as coal-fired power plants still fuel electricity generation, fossil natural gas is burned to produce most hydrogen, and alcohol-based fuels are often produced with fossil-fueled machinery. READ MORE