Diesel’s Last Decade

Here’s my prediction for the next 10 years: diesel engines will no longer be made. Let’s declare the 2020s diesel’s last decade and explore how to make this prediction a reality.

In 2020, I wrote an article entitled “The Path to Zero” where I laid out five beliefs that can propel us toward a low-carbon future. Among them, was this: “The path to zero [carbon] means we should replace more bad, while we add more good, to the energy grid…” and went on to explain that carbon isn’t the only problem we’re facing. When I published that idea, I had diesel on my mind, so my declaration of independence from diesel isn’t a new thought, but now the idea is gaining momentum.

A Few Facts About Diesel

About 85% of diesel fuel’s mass is carbon, and when burned, you might assume by its exhaust that a great deal of carbon gets thrown into the atmosphere. That’s not totally wrong, but the CO2 emissions from diesel are actually slightly lower than for gasoline (73.25 g/MJ vs. 73.38 g/MJ), and aren’t nearly offensive as, say, kerosene or coal.

Diesel is also a relatively dense fuel. It burns hot and as a result, delivers more miles per gallon than comparable gas-powered engines. It’s the combined power density and efficiency that explains the engine’s popularity for long-haul, heavy freight transportation including trucks, ships, buses and trains. Diesel paved the way for massive productivity improvements in everything from agriculture to zinc mining. With the expansion of diesel’s footprint, however, came significant environmental and health downsides.

Diesel’s Damaging Emissions

Exhaust from diesel engines is full of criteria pollutants like CO2, SOx, and particulate matter, which can contribute to smog, acid rain, and soil and water pollution. In some cases, exposure to particulate matter can lead to heart and lung disease, respiratory damage, and even premature death.

The Energy Information Administration (EIA) says consumption of diesel fuel by the U.S. transportation sector in 2019 was about 47.2 billion gallons, which accounted for 15% of total U.S. petroleum consumption. On an energy content basis, this accounted for about 23% of total energy consumption by the transportation sector, emitting 468 million metric tons of CO2, or about 25% of total transportation emissions. That makes the presence of diesel big in our midst and worthy of a serious conversation about its end-days.

A Cleaner Alternative to Diesel

Propane autogas offers comparable range, efficiency, and power when compared with diesel, but with a lower total cost of ownership, fewer maintenance needs, and significantly reduced emissions. With propane, particulate matter emissions are near zero when used in modern engines. With a simple three-way catalyst, propane reduces NOx in engines by 94% compared to best-in-class diesel counterparts. The best propane-powered engines are being certified to the CARB ultra-low NOx standard (0.02 g/hp-hr). Additionally, with the arrival and growth of renewable propane, propane-powered transportation is poised to further reduce CO2 emissions and revolutionize clean energy. Both conventional and renewable propane are part of a low-carbon future because they are cleaner than conventional diesel.

Get Schooled on Propane Buses

Here’s just one thing we could do to make the 2020s diesel’s last decade: convert all the school buses in America from diesel to propane. The savings in fuel and maintenance costs alone would be enough to hire 23,000 new school teachers for students across the country. The EPA’S Clean School Bus Program recently awarded funding for the purchase of clean school buses. If their goal is to remove diesel buses from school transportation, they should consider the following facts:

• Propane-powered school buses equipped with newer engines emit 60% to 94% fewer NOx emissions, depending on the model year, than comparable diesel-fueled school buses.
• Today’s propane engines are 90% cleaner than the mandated EPA NOx emission standard.
• Unlike diesel-powered units, propane buses do not require costly diesel after-treatment systems and diesel exhaust fluid to mitigate NOx emissions.
• Particulate matter emissions from propane school buses on a typical operation cycle are near zero.

Furthermore, propane school buses do not experience cold start issues that are common with diesel models, making them an ideal choice for student transportation in any climate. Today, propane buses transport 1.3 million children each day, helping school districts meet sustainability goals while supporting the well-being of bus drivers, student passengers, and their communities.

Accelerating Diesel’s Demise

In propane and propane engines, we have the clean fuel and technology necessary to very affordably (unlike battery electric or hydrogen fuel cell alternatives) accelerate diesel’s demise today without requiring compromises in power, range, or performance. It is clear to me and an increasing number of fleet operators around the country that the path away from diesel – and toward zero emissions – runs through propane.

For more comparative facts about diesel vs. propane, please visit https://propane.com/for-my-business/fleet-vehicles/propane-autogas-versus-diesel/.

About the Author

Tucker Perkins, President and CEO

Tucker is an engineer, entrepreneur, business leader, speaker and is now the president and chief executive officer of the Propane Education & Research Council. He has worked in the propane industry nearly his entire professional career, having served as the director of business development for Inergy, chief executive officer of Premier Propane, and the chief operating officer of Columbia Propane, a unit of the Columbia Energy Group. Tucker is also the former chairman of a PERC advisory committee on engine fuel matters and is active with the National Propane Gas Association and the Virginia Propane Gas Association.