Since the advent of diesel fuel, scientists have been working to make it cleaner and more efficient. In recent years, the popularity of “clean diesel” has grown, which is term that designates diesel fuel that contains less sulfur than traditional fuel. This improvement helps diesel engines produce fewer harmful emissions and now is the standard for use in diesel vehicles and machinery around the country.
However, diesel fuel may be better but still, these engines still produce a great deal of nitrogen oxide (NOx) emissions and other harmful toxins. Because of the nature of the fuel, even “clean diesel” isn’t particularly “clean.”
In contrast, propane is a naturally clean fuel. That’s due to the chemical makeup of the propane molecule (C3H8) which is 8 atoms of hydrogen to three atoms of carbon. While many think that hydrogen will be an ideal fuel in the future, propane’s high hydrogen, low carbon composition provides a reliable and tested clean transportation product today, with lower emissions and pollutants than gasoline and much less than diesel.
Compared to clean diesel, propane-powered school buses were found to produce 96% fewer NOx emissions in a 2018 study conducted by researchers at the University of West Virginia. It’s important for school districts to consider NOx-reducing engines as the emissions can be dangerous to those who breathe them in. Diesel emissions can irritate asthma and other respiratory problems, which can be especially harmful to students who ride school buses.
Aside from the health benefits for students and the environment, propane is much more cost-effective than diesel. Considering all the benefits propane has to offer, it is a great choice to power school buses and many other types of fleet vehicles. Schools around the country continue to employ diesel buses to transport students, even though the buses are loud, smelly, expensive and have low fuel efficiency. However, more and more schools have made the switch to propane-powered buses because of the many success stories that have been shared by school districts in Missouri and across the U.S., and because switching just makes sense.
On paper, clean diesel may seem like a good choice, but the results do not translate into the real world. Unless the rigorous maintenance required for clean diesel engines is kept up, performance degrades over time and the engines fall below emissions standards. As a diesel vehicle ages, even after just a few years, the system can begin to degrade and harmful emissions levels increase. Not only is this dangerous for the environment, it also results in reduced performance of the vehicle as engine components begin to fail. To mitigate these issues, diesel engines must regularly undergo the rigorous maintenance recommended by manufacturers. These costs add up, because in addition to parts and labor, the vehicles are missing time on the road too.
Propane engines do not require any of this extra maintenance time and expense, making them a cost-effective choice over the life of the vehicle. Plus, propane engines will remain compliant with EPA and CARB emissions standards over time and can even exceed these standards. Unlike diesel, propane does not require additional fuels and filters to operate properly. Also, the price of propane is consistently less than that of diesel, and it tends to remain steadier, allowing for easier budgeting. Considering fuel prices and maintenance costs over time, propane vehicles can operate at about 19 cents per mile, compared to diesel fuel at 80 cents per mile. With the many miles that Missouri school buses travel each year, these savings can save a significant portion of a school’s transportation budget. Schools can then turn these savings into more resources for students, like new textbooks, better technology, or more teachers.
It may be tempting to consider clean diesel in a fleet of school buses, but propane is a better choice because it truly is a clean fuel. Propane autogas is nontoxic, so in the unlikely event of a spill, it will not contaminate nearby soil or water, unlike other fuels. Propane buses will continue to perform at a high level over time without the rigorous maintenance demanded by a diesel engine. Plus, propane engines are quiet, making propane buses a safer environment for bus drivers and students. Propane produces fewer emissions at a lower price, so it is the clear choice for schools that want to protect their communities and their budgets.
Learn more about propane autogas school buses.