As automotive and technology companies collaborate on connectivity and futuristic, over-the-air charging for consumer vehicles, the school bus industry is focusing on alternative fuel innovation that accommodates government regulation, incentive grants, low cost operations and passenger health.
“The automotive industry is truly so diverse, and different niches need different fueling applications. There’s no silver bullet for fuel options,” said Brian Carney, group account director at ROUSH CleanTech.
There continues to be a big push toward propane, as all three major OEMs now offer it as do many of the Type A manufacturers, and CNG has been gaining ground in not just California. But the simple fact is that diesel continues to dominate the school bus market. So how can some 90 percent of the industry be influenced to go green? The answer lies in quickly emerging drop-in fuel that requires no new infrastructure investments.
While biodiesel-petroleum blends are abundant, a next-generation and entirely different green diesel is on the horizon that burns cleaner than traditional Ultra Low Sulfur Diesel and performs better. Proponents claim that Renewable Diesel, or RD, is more sustainable and safer to handle, due to its renewable properties derived from animal and fish fat, vegetable oils and greases.
According to the U.S. Department of Energy, producing RD involves hydrogenating triglycerides to remove metals and compounds with oxygen and nitrogen using existing refinery infrastructure. Distinguished by this unique processing method, RD is becoming a good fit for fleets subject to greenhouse gas emissions and other strict pollutant reduction requirements, as RD promises 65- to 90-percent reduction in GHG and 9 percent fewer emissions of NOx. It can be used in all diesel vehicles and fueling infrastructures without warranty or code issues, making it an easy start up.
While a great option for school transportation, access is a barrier. For now, the industry will have to watch the performance of new commercial test fleets that ramped up on the West Coast last year. In California, for instance, San Jose Unified is the only known school district using RD in its fleet. Lead Equipment Mechanic Andrew DeBolt said the district is transitioning the entire 72-bus fleet to RD as well as department trucks, vans and off-road equipment.
DeBolt, a former Ford dealer mechanic, said RD is offering at least the same fuel economy as ULSD with less soot clogging DPFs. He added that RD is also a better option than biodiesel because there are no warranty or clogging issues. And the district’s 10 remaining CNG buses are being phased out in favor of new diesel buses that will be fueled by RD.
“We’re going to diesel so we can have reliability,” he said. “If you take it one step further, it means one less engine to train on, it makes the shop is safer and there are fewer parts to stock. It just makes sense.”
Nearby, Oakland, California, became the first major U.S. city to switch entirely to RD for its 250 diesel-powered fleet vehicles, including street sweepers, dump trucks, tractors, mowers and construction equipment. Six months after launching, there have been no reported issues as the fuel is fully compatible with existing equipment.
“If we didn’t tell the drivers, they wouldn’t have noticed. We didn’t make any modifications to vehicles or fueling whatsoever. We made a significant emission improvement overnight,” said Oakland’s Fleet Service Director Richard Battersby, who is a scheduled presenter this month at the STN EXPO on this very topic.
With Finnish oil refining company Neste serving as a supplier, Oakland stands to utilize about 230,000 gallons of RD this year, though it’s important to note it costs about 10 cents per gallon more than regular diesel. Still, the cetane number of RD ranges from 75 to 90, compared to petroleum diesel (40 to 55) and biodiesel (50 to 65), equating to improved performance.
In Oregon, the City of Portland and the Eugene Water and Electric Board are two of the largest fleets using and praising RD. Fleet managers there said they have noticed fewer alerts and regens from vehicle emission systems. With less black soot emitted into particulate traps, for example, Battersby said he expects Oakland’s fleet maintenance costs to reduce.
The biggest issue, however, continues to be availability.
“Renewable Diesel is not everywhere. The industry has some catching up to do, as demand is growing faster than supply. Over time it should gain more access, because it is a superior fuel for diesel engines,” said Rick Wallace, senior policy analyst at the Oregon Department of Energy, who’s extensively studied the fuel.
Additionally, renewable natural gas and propane, the latter of which is already is being used in Europe, are currently undergoing test phases. During a CAL-START webinar last month, Pat O’Keefe, CEO and president of NexGen Fuel, said renewable gasoline and propane first require specification standards before they could be put into wide-scale use.
Progress in CNG
Meanwhile, both the acceptance and infrastructure of propane and CNG continue to accelerate. While CNG-powered vehicles have had explosive growth in corporate and utility fleets, the school bus CNG market has seen a slower pace. That seems to be changing, as governments provide incentive funding and manufacturers add more products to the market.
Blue Bird and Thomas Built Buses have offered CNG in Type D transit-style applications for years, and now both are coming are offering options for their respective Type-C flagship models, the Vision and Saf-T-Liner C2. Lion Bus was the first to announce a Type C option last spring powered by a NGV Motori version of the International DT466 engine. For the Type A segment, Collins Bus Corporation offers its new NEXBUS CNG powered by the Cummins Westport WiNG Power System on a Ford E-450 cutaway chassis.
Real-world use of CNG has been positive, especially when a whole community collaborates. For nearly two decades, the entire community of Bakersfield, California, has been committed to achieving cleaner air, which has driven the successful adoption of CNG vehicles for Kern County school transportation. Beginning in 1999, the district obtained grants to transition its bus fleet to CNG power and construct a 24/7 fueling infrastructure, also accessible to public and private fleets.
Now with 56 CNG buses (a combination of Blue Bird and Thomas) and high demand for natural gas fueling services, the district is upgrading its fueling station using $1.75 million in federal and state grants. By September, phase two improvements will bring equipment for faster fill ups and a trailer unit for on-the-spot refueling of smaller CNG fleets in remote areas.
“We think of the whole market,” said KCSOS School Transportation Director Sheryl Boe. “Profits from the station will help with expansion and repairs. We will get to a point where we give to the general fund for other educational needs.”
The road’s been a little bumpier for Mansfield ISD in Texas. As early adopters in 2006, the district leveraged a grant for conversion kits to install CNG power on two buses. Over the past decade, the department added a two-pump fueling station and 37 CNG buses (Thomas Built and TransTech) to its 242-vehicle fleet. On average, the alternative buses have each rolled from 70,000 to 100,000 miles with a few snafus.
“When they go down, they are out for weeks at a time,” said Assistant Transportation Director Jason Gillis, who explained the challenges of finding mechanics to repair various technologies on both the buses and at the pump. “It was saving us money when diesel was expensive. But training costs are up, and CNG is now the same per gallon as diesel.”
For now, the district uses CNG buses for shorter special education routes, while the rest are utilized as backup transportation.
Cost Advantage of Propane
A byproduct of oil refining and natural gas processing, propane has become an attractive alternative due to its availability and the lower entry cost for fueling infrastructure.
Outside of Phoenix, the Kyrene School District now runs 85 percent of its school bus fleet on propane autogas. The school district first adopted the fuel in 2014 when it purchased 25 Blue Bird Vision Propane-Powered buses. This spring, it added 73 more. Equipped with a Ford 6.8L V10 engine, the 98 buses are powered by ROUSH CleanTech propane autogas fuel systems.
Currently, the district averages $1.15 per gallon compared with $1.50 per gallon for diesel. In addition, the district benefits from a 36 cents per gallon tax rebate provided by the federal government. And a propane provider is helping to install an onsite fuel station to further reduce the cost per gallon.
Drivers also like the quieter ride. “This allows drivers to better interact and talk with students on the bus without competing with a diesel engine,” said Eric Nethercutt, director of transportation and facilities for Kyrene School District.
Electric Baby Steps
Hybrid and plug-in electric school buses are represented in miniscule numbers. But there’s traction. A new report from Navigant, Transportation Forecast: Medium and Heavy Duty Vehicles, predicts that global annual electric and hybrid bus sales are expected to grow from just more than 9,000 vehicles in 2016 to 52,000 in 2025.
“There are exciting things coming to school buses. Hybrid and electric will become increasingly popular over the coming years with battery costs coming down,” said David Alexander, senior research analyst with Navigant Research.
The industry has tried hybrids once already with little luck, as IC Bus, Thomas and Collins Bus all encountered high vehicle cost, power plants and supply-chain issues that caused the companies to abandon their respective projects. Since then, several OEMs have embraced an even cleaner alternative: zero-emissions electric.
Trans Tech debuted the first factory-built, battery-powered electric school bus in Oct. 2011 at the NAPT Trade Show. While that initial model never achieved NHTSA certification for route service, two years later Motiv assumed the grant project and announced the new Trans Tech “battery agnostic” SST-e would hit the road in 2014 at Kings Canyon Unified School District in California. The bus achieves a 50-percent charge in under an hour and is fully charged in eight hours.
Lion Bus is the first to fill electric desires in the Type C segment with its eLion, mostly in its home province of Quebec, though several initial orders in the U.S. are being filled this month.
Some districts are opting to convert their diesel buses to electric through companies like ADOMANI, which offer all-electric powertrain conversions through partnerships with dealers like A-Z Bus Sales and manufacturers like GreenPower Bus.
“The demand is clearly there as school districts are ready to add electric school buses to their fleets and replace older high polluting diesel buses,” said ADOMANI Chief Executive Officer Jim Reynolds.
In California, where incentive grants are sparking things, at least nine school districts in the South Coast and San Joaquin Valley air basins intend to eventually put a total of 25 GreenPower all-electric school buses on the road. They will include the EVS 03 (Type C) and EVS 01M (Type A) all-electric school buses, powered by batteries with a range of 100 miles on a single charge.
“California is one of the leading states in air quality programs,” said GreenPower Chief Executive Officer Phillip Oldridge. “We expect as the transition to electric picks up momentum, that we will continue to see increased adoption of our all-electric school buses.”
Other ongoing electric school bus projects include one by the Clinton Global Initiative, which selected a district outside of Los Angeles, Torrance Unified School District, to participate. In May, TUSD Transportation Manager Mark Plumb said the district’s two electric buses are “about to hit the road.” The two-year project has progressed slowly and has been expensive, Plumb added, but the $900 annual electric bill to charge the buses beats the $9,000 annual bill for traditional fuels. He also shared that when electric buses are plugged in, they provide power back into the power grid to help reduce costs and consumption.