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Diesel School Buses Continue Market Domination Amid Move Toward Lower-Emission Alternatives

By: Ryan Gray

17 June 2026 at 03:33

New data shows that nearly three-quarters of all registered school buses are powered by diesel, even as the U.S. Environmental Protection Agency Clean School Bus Program is expected to extend federal funding to include the fuel.

The S&P Global Mobility TIPNet data for December 2025 indicates internal combustion engines account for 98 percent of all power in U.S. commercial vehicles, 76 percent being fueled by diesel. Gasoline is powering 23 percent followed by 0.5 percent natural gas and propane. Electric vehicles account for the other 0.5 percent.

A deeper analysis conducted this spring by the Engine Technology Forum (ETF) found that school districts are opting to replace their aging school bus fleets with diesel. The ETF said 72 percent of the 2010 and newer model-year school buses are diesel, a 5-percent increase from 2023. The diesel buses rely on SCR and particulate matter filters, the latter introduced in 2007, to reduce levels of PM and nitrogen oxide, or NOx, by more than 90 percent compared to pre-2007 engines.

“Fleet turnover is one of the most effective tools we have to improve air quality today,” said Allen Schaeffer, executive director of ETF, in a statement last week. “The increasing share of 2010 [and older] model-year diesel buses show that school districts are making practical, cost-effective investments that deliver immediate environmental and operational benefits for students.”

Meanwhile, diesel school buses make up over 87 percent of the total fleet of school buses. The ETF analysis found about 18 percent of the national fleet regardless of fuel are pre-2007 model years.

The analysis also found that electric school buses account for only 1.1 percent of the national fleet. Meanwhile, ETF said a news report last year indicated propane school buses make up about 5 percent of the national fleet.

Diesel School Buses to Further Benefit from Federal Rulemaking, Funding?

The school bus and larger commercial truck industry await a new final rule on 2027 NOx and PM levels from the EPA, which is expected this summer. EPA is also expected to announce the return of the five-year, $5-billion Clean School Bus Program, which has been on hiatus since January of last year. The agency indicated in an RFI published earlier this year that it was considering adding biodiesel and renewable diesel as fundable fuel types.

“If we get back to the idea that an EPA program on school buses is to bring the most benefit to the most school districts to make school bus emissions cleaner, using renewable fuels ranks high on the list of accessible and affordable and good options,” Schaeffer, told School Transportation News.

Additionally, Congress is currently debating increased funding through the Diesel Emissions Reduction Act. Senate bill 2235 and would also increase spending to $100 million for each fiscal year 2026 through 2029, according to the Congressional Budget Office. H.R. 2140 contains the same spending amounts and remained in the Energy and Commerce committee.

An online STN survey of transportation directors conducted in April indicated that only 11 percent of 193 respondents are prioritizing electric or alternative school bus purchases for the upcoming school year compared to the previous school year. Diesel school buses also continue to be the most common fuel type, according to registrants of next month’s STN EXPO West conference who are signed up to attend the Transportation Director Summit.

Still, some school districts are maintaining previous plans to phase out diesel and expand electric and propane school bus purchasing. Cypress-Fairbanks Independent School District in the Houston, Texas area — the largest school bus operation in the state — has no current plans to purchase diesel school buses as it focuses on propane and electric, said Bobby Williams, assistant director of transportation for fleet maintenance.

He said propane now represents 41 percent of the district’s fleet, with diesel coming in second at 34 percent.

Pittsburg Unified School District near San Francisco, California, operates a small fleet of 33 buses, with nine powered by renewable diesel.Matthew Belasco, the district’s director of transportation, cited California’s 2035 mandate to transition to zero-emissions school buses as a leading reason why fellow districts have moved away from diesel, despite technically still being able to purchase them for the next nine years.

The district currently operates seven electric school buses and 17 propane.

“Most state and federal funding programs have been focused on supporting zero-emission and, in some cases, low-emission alternatives, like propane,” he added. “We got some funding for propane a few years ago. Generally, though, districts that seem to be looking to replace buses have moved toward electric or propane options.”

The post Diesel School Buses Continue Market Domination Amid Move Toward Lower-Emission Alternatives appeared first on School Transportation News.

Report Highlights Propane and Electric TCO for School Bus

School Transportation News

By: Ryan Gray

4 May 2026 at 17:32

LAS VEGAS – As the school bus industry awaits the return and final awards of the Clean School Bus Program, propane and battery-electric continue to offer the most consistent operational cost savings.

That was the verdict of the 2026 State of Sustainable Fleets report produced by TRC Clean Transportation Companies and released this morning at the opening of ACT Expo. The published conclusions are derived from a national survey of light-, medium- and heavy-duty fleet operators across not only the school sector, but transit, refuse, delivery, freight, utility, municipal, and private contractors. The report also relied on industry interviews, market data, policy and funding analysis, and lifecycle and cost analysis.

Propane autogas — including renewable propane, which ACT News and the Propane Education and Research Council previously reported is projected to reach 300 million gallons produced by 2030 — and electric arrive at lower total cost of ownership in different ways, the report highlights.

Propane school buses traditionally cost about 10 percent more upfront to purchase than diesel counterparts. The price of EPA’s new rule expected to be updated next month would have resulted in additional costs of $8,000 to $18,000 for each new diesel vehicle. Discussions at last month’s STN EXPO East provided similar figures. But depending on how the pending 2027 federal NOx regulations update is rewritten, increased costs tied to diesel warranties and end-of-life provisions could be cut in half, according to a panel Monday morning on EPA27, with speakers Andrea Lukas of Cummins and David Hillman of International.

The speakers noted that the low NOx requirement of 0.035 g/brake-hp-hr remains with the effective date of Jan. 1, 2027 still ineffect. The separate issue of GHG and the prior regulation in effect mandating the use of battery-electric in California Air Resources Board states to be addressed with the new rule.

Daily operations are more immediately impacted by fuel prices amid the Iran war. The survey found that Midwest school districts were paying $1.31 to $1.90 per gasoline gallon equivalent, or 47- to 63 percent less than gasoline, to fuel their propane school buses. The U.S. Department of Energy said private propane fueling nationwide averaged $2.91 per GGE in January 2025.

Meanwhile, diesel prices at the pump fell $0.05 to a national average of $5.35 per gallon and gasoline increased by 7 cents to $4.12 per gallon, according to the U.S. Energy Information Administration. The State of Sustainable Fleets report found that propane Autogas delivers 50-percent lower daily fuel costs than diesel and 40 percent lower than gasoline.

Overall, 39 percent of the fleets surveyed recovered operational costs savings compared to vehicles replaced by propane.

In terms of GHG emissions, the responding fleets reported that propane offered a 59-percent reduction in California compared to gasoline. Like battery-electric, propane emits zero pounds of sulfur dioxides, according to the U.S. Department of Energy’s AFLEET data. However, that is where the similarities to propane end.

Electric school buses of course emit nothing from the tailpipe. In fact, they don’t have tailpipes. Electricity for charging in California offered a 59-pecent reduction in lifecycle GHG emissions last year compared to diesel. Propane, while reducing NOx by over 90 percent compared to diesel (including biodiesel blends and renewable diesel), emits nearly 640 percent more CO2. It emits slightly higher PM10 than diesel and same levels of PM2.5, the especially fine particles of soot that are most dangerous to children.

**Comparative chart of emissions by fuel type. Source: U.S. Department of Energy AFLEET, via World Resources Institute Electric School Bus Initiative.**

Tips for Making Battery-Electric Work

The report forecasts that medium- and heavy-duty electric vehicle registrations — which set a record last year — will fall in 2026 due to the loss of the EV tax credits and “pivots announced by manufacturers.” Registrations of electric school buses was up 60 percent, despite the absence of EPA Clean School Bus Program funding but with continued state support in California, New York and Maryland among others. And electric school bus registrations were drastically better than anemic growth in electric big trucks.

EVs are showing improved TCO. Fifty-seven percent of the fleets surveyed reported operational cost savings on medium-duty electric vehicles compared to the vehicles they replaced. The biggest savings occur on routes that fit electric duty cycles, managing vehicle charging and limiting maximum loads. For example, the report found that fleets can also save 30 percent by shifting to off-peak charging cycles, and doubling or tripling charging windows can cut capital and fueling costs by more than half.

Additional best practices include right-sizing charging equipment, maximizing charging windows and charging multiple vehicles per station.

Costly charging infrastructure remains a challenge, but funding assistance continues, despite the termination of the federal EV credit. The report cited a $6 billion investment by electric utility member companies of the Edison Electric Institute to support charging infrastructure through consulting services, customer rebates, make-ready infrastructure, and end-to-end charging solutions.

Overall, 54 percent of the fleets surveyed said the plan is to increase usage of EVs in the next two years. In the school bus sector, the report cites S&P Global Mobility data showing that 2,289 new electric school buses were registered last year, a 59-percent increase from 2024.

The U.S. Environmental Protection Agency had yet to announce the latest and final funding opportunities under the five-year, $5-billion Clean School Bus Program at this writing. But the remaining $2.7 billion to be awarded will result in more electric school bus orders over the coming years, as well as propane and likely diesel. In addition to California and New York, which have large funding programs to try and meet their mandates that school buses be all-electric over the next two decades, the report cites increased state funding elsewhere, such as new programs in Illinois, Michigan, New Jersey and New Mexico.

Despite the Lion Electric bankruptcy and consolidation of operations to solely serve Quebec, the State of Sustainable Fleets reported positive news for electric school bus manufacturing. It cited Blue Bird’s all-time record revenue and profit posted in the fourth quarter and full year of 2025. Thomas Built Buses also announced its first Type D electric school bus, which is now available to order. IC Bus continues manufacturing and selling its CE Series electric and is offering bundled consulting, financing and maintenance services.

Diesel Continues On

The State of Sustainable Fleets report cited an American Trucking Associations blog in November that the EPA Clean Trucks Plan, which was set to reduce NOx by more than 80 percent and PM by 50 percent for 2027 model year engines, will remain largely unchanged.

A final rule was expected this spring but no announcement had been made at this writing.

“All major manufacturers have developed at least one HD engine capable of meeting those requirements,” the report states.

The report at ACT Expo suggests the final rule may remove warranty and useful life provisions that are expected to increase new diesel vehicle costs in the range of $8,000 to $18,000, with the Cummins-International session earlier Monday again indicating those figures could be less. The new final rule from EPA will eventually result in more specific cost figures.

Still, a “pre-buy, no-buy” dynamic is expected this year and next. The report states that manufacturers are already selling out new build slots for the third and fourth quarters of 2026.

As the industry awaits the Clean School Bus Program announcement and its expected incentives for using biodiesel and renewable diesel, the report found 56 percent of fleets used one of these drop-in fuels, more than double the number from 2023. Twenty-one percent reported utilizing both biodiesel and RD.

Benefits of using RD, the report confirmed, are improved cold-weather performance over biodiesel and fewer diesel particulate filter changes while realizing maintenance savings of approximately $0.015 to $0.02 per mile.

What About CNG, Hydrogen and … Hybrids?

The report also covered CNG, hydrogen and hybrids. But CNG is no longer manufactured as an option for the school bus sector, and hydrogen as yet to be offered as a viable power plant. The school bus industry did test the applicability of hybrids a decade ago and shortly thereafter abandoned those efforts. But hybrid is showing some promise for tractor-trailer trucks, the report notes.

“Adoption of a new technology is almost always driven by a combination of regulation, economic savings and incentives,” Patrick Couch, senior vice president of technical services for TRC Clean Transportation Solutions, told School Transportation News last week. “For hybrid technologies, OEMs will be focused on high-fuel use applications and applications where they are allowed by regulations and operationally more suitable than alternatives. School buses may be a secondary or tertiary focus for hybrid product offerings.”

The post Report Highlights Propane and Electric TCO for School Bus appeared first on School Transportation News.

RNG-Fueled Fleets in California Mark Five Years of Carbon-Free Outcomes

Alternative Energy HQ

By: newenergy

4 September 2025 at 00:41

RNG Remains the Most Immediate, Cost-Effective Way to Decarbonize Heavy-Duty Transportation Washington, DC – Last calendar year marked the fifth consecutive year that commercial fleets in the State of California fueled by bio-CNG (renewable natural gas, or RNG) achieved a carbon-negative transportation outcome, according to a report released today by The Transport Project (TTP) and RNG Coalition alongside partner California Renewable Transportation Alliance (CRTA). Lowest …

The post RNG-Fueled Fleets in California Mark Five Years of Carbon-Free Outcomes appeared first on Alternative Energy HQ.