Thursday, June 26, 2014

Autogas on the rise as world’s preferred alternative fuel

June 23, 2014 (LBT) - Rapidly gaining popularity as cleanest and most environmentally friendly automotive fuel, Autogas is lmost 50% more cost effective than using a petrol vehicle

Road travel remains an essential feature of the world’s transportation mix, and is of tremendous importance to the many commuters who use this mode of transport. Autogas is the most commonly used and widely accepted alternative to conventional oil-based transport fuels, petrol and diesel due to the impressive environmental benefits it offers and its practical and cost advantages. Autogas is the third most popular automotive fuel in the world, with approximately 23 million vehicles in use around the world and over 57,000 refuelling sites.

Autogas is the most accessible alternative fuel and driving an Autogas vehicle is safe, easy and in several countries, almost 50% cheaper than driving a petrol vehicle. Autogas also has an octane rating that is between 90 and 110.

The use of Autogas is extremely popular in several countries and regions around the world including the European Union, Turkey, Australia, South Korea, Hong Kong, India, Croatia, Lithuania, the Philippines, Macedonia and Serbia with several of these countries having well-developed Autogas markets.

Turkey has the highest percentage of Autogas vehicles in the world. Some 37% of passenger cars run on Autogas, and Autogas consumption now exceeds petrol consumption. In Australia, there are over 615,000 Autogas-powered cars and is especially popular with taxis. In Hong Kong, all taxicabs rely on Autogas while many public light buses also rely on Autogas.

In England, Queen Elizabeth II converted her vehicle fleet to Autogas, including her high fuel consuming Rolls-Royce, while in the USA President Barrack Obama has issued a presidential memorandum that all federal car fleets must buy only 100% alternative fuel vehicles by the end of 2015. Currently in several states in the USA school buses, taxicabs and sheriff and police cars have already switched over to Autogas.

Autogas is also significantly better for vehicle engines and oil and filter life can be doubled as Autogas leaves fewer deposits in the combustion process than petrol or diesel, reducing the chances of oil contamination. Cylinder and piston wear is reduced as Autogas mixes better with air, as it enters the chamber as a gas, as opposed to diesel and petrol, which enter as a liquid.

Given that alternative, cleaner automotive fuels have a key role to play in addressing the worsening environmental problems caused by the rising consumption of road transportation fuels, Autogas used as an automotive fuel is rapidly establishing itself in many countries as by far the most important of these fuels. The strong case for Autogas as an environmentally friendly fuel rests on the fact that noxious emissions from Autogas are among the lowest of all automotive fuels.

It has been proved that driving on Autogas leads to a significant reduction in CO2 emissions compared to a petrol vehicle while Autogas emits almost no black carbon, a pollutant which is also the second biggest contributor to climate change. Autogas fuelled cars also generate 96% less mono-nitrogen oxides than diesel and 68% less than petrol while also emitting 120 times less small particle emissions than diesel vehicles.

In order to meet the diverse challenges associated with pursuing sustainability, security and competitiveness, the world will need to rely on a wide range of energy solutions and make intelligent use of resources by employing each available energy form where it is most effective. Autogas, automatically produced during the production of natural gas and oil, is a readily available resource that can and should be used to help the world meet its energy needs. In this context, it is essential to move the passenger car fuel sector towards a more diverse and flexible system - Autogas. Read more here.

Monday, June 23, 2014

A look inside the UPS refueling station build...

Watch this great video for a behind the scenes look inside the CleanFUEL USA garage as we begin to build the refueling equipment to fulfill the UPS propane autogas commitment.



UPS Still Getting Traction from Propane Autogas Announcement


When UPS announced investment in 1,000 propane autogas delivery vehicles and 50 refueling stations this year, it represented the single-largest such commitment for propane autogas vehicles. The historic adoption continues to make headlines, inspiring an interview with CleanFuel USA CEO Curtis Donaldson in the Houston Chronicle, and the posting of the PERC-created Straight Talk video with UPS on industry websites.

Friday, June 20, 2014

Freightliner Custom Chassis announces start of S2G production


Freightliner Custom Chassis Corporation announced the start of full production of its propane-autogas S2G medium-duty work truck this week. The S2G pairs FCCC’s popular, durable S2 chassis with the only factory-installed propane autogas engine available for the medium-duty truck market. The S2G is powered by an 8-liter V8 “big block” engine - featuring a CleanFUEL USA Liquid Propane Injection system - offering up 339hp and 495 ft-lbs of torque. Initial orders for the truck will focus on the propane-delivery market; FCCC has plans to expand into other applications and industries beginning in 2015. For more information, visit S2Gtruck.com

Thursday, June 19, 2014

Evolving Alt-Fuel Infrastructure

Managing the Best Option
Most professionals, no matter which alternative fuel they represent, admit there isn’t a single solution that will work for every fleet. It is more a matter of looking at the different options and deciding which will fit a particular operation.

“There is no one alternative fuel that fits perfectly for all fleets,” said Tucker Perkins, chief business development officer for the Propane Education & Research Council (PERC). “Similar to CNG, propane autogas delivers long-term operating cost efficiencies and emissions reductions.”

When it comes to infrastructure, propane autogas advocates have touted the low cost of refueling installation and maintenance, which can make it appealing to fleets both big and small. According to Darren Engle, director of government relations for Blue Star Gas, there is another benefit that must be highlighted when it comes to propane autogas: fiscal independence.

“With 98 percent of the propane autogas coming from the U.S., it reduces our dependence on foreign oil drastically,” Engle said, adding that the future will bring more collaboration between propane autogas marketers to help create fueling networks that span the country, allowing you to drive a propane-autogas-fueled vehicle from California to Washington, D.C. “Right now we have about 3,000 sites available in the U.S. where you can refuel. The challenge is that there’s no continuity in regards to pricing. They can be all over the board. Sometimes, the published price is what it would cost to fill a barbecue cylinder, not what it is to fill a vehicle.”

Propane autogas also has some changes looming in the very near future in terms of technology, according to Perkins.

Currently, when fueling a propane vehicle, drivers must wear gloves and protective eye wear. This is because, when the tank is filled and the nozzle is removed, a small amount of the fuel escapes. Worldwide, there are essentially seven different nozzle technologies that are being used. When UPS announced plans to purchase 1,000 propane autogas package delivery trucks and initially install 50 fueling stations at UPS locations, PERC saw this as an opportune time to deploy a new nozzle technology, which is modeled after a design currently used throughout Europe.

“The new nozzle only requires one hand to operate, making it very similar to a gasoline-style pump,” Perkins said. “The connection automatically mates and secures, and you’re able to flow the gas. Emissions are significantly reduced, with less than 1 cubic centimeter escaping during operation. In many cases, that’s less than half of the best technology out there now.”

The UPS deployment will also allow PERC and its partners to access data on driver fueling behaviors and see what their fueling experience is like.

“It was the perfect demonstration lab for us to test this new technology,” Perkins added. “We’ll get the nozzle into at least 30 of the UPS sites, we’ll keep good records, and then begin to build a body of evidence that allows us to mandate these into the code and standards."

The emissions are so low, according to Perkins, that there is no need for personal protective equipment or training. From a safety perspective, these nozzles give users more flexibility. PERC is working in partnership with a number of other companies to voluntarily use this equipment across the board at their own locations. Read more here.

Economics fuel change to propane buses in Toppenish

From the exterior, the Toppenish School District’s two newest school buses look like the others in the fleet of 20. But a closer look reveals green stickers at the back and near the passenger doors. One word — propane — tells the story.

Toppenish this month became one of a handful of school districts in the state to inch toward propane by adding two propane-powered school buses in an effort to fight rising diesel prices by finding a cleaner and cheaper fuel.

“We’re really anxious to try them out,” said district Transportation Director Blaine Thorington. The two vehicles could be ready for some summer school routes.

According to Educational School District 105 Transportation Coordinator Dan Payne, Toppenish is the only district in the region to have propane-powered school buses. Seattle, Camas and Tonasket school districts also have them, he said.

The two 77-passenger school buses were ordered in January 2013 from a Portland dealer, but production delays in North Carolina tested the patience of district officials, said Thorington, also a longtime Toppenish city councilman.

The first bus arrived in Toppenish two weeks ago and the second late last week. A smaller third bus, intended for physically disabled students, will arrive in six months.

The use of propane as an alternative fuel is growing nationally as school districts grapple with rising gas and diesel prices and shift toward more green initiatives. While the majority of school buses is powered by diesel fuel, alternatives like propane, biodiesel and compressed natural gas have become more popular over the years.

A gallon of propane, Thorington said, costs $1.90, significantly less than diesel, which is over $4 per gallon at several locations. Add in a 50-cent-per-gallon tax rebate and the cost of propane goes down to $1.40.

Each of the two conventional buses costs $104,000, Thorington said. In addition, the cleaner characteristics of propane — no soot residue or carbon — means fewer oil changes and maintenance inspections.

“Because of the lower maintenance costs and gas prices, they may cost less in the long run,” Payne said.

Compared with diesel-powered vehicles, propane buses run quieter, emit less pollution into the air and the cabin, and perform as well as a standard bus.

There are drawbacks, though. Propane gets less mileage per gallon than diesel and not all of the fuel can be used.

“You can’t use every drop,” Thorington said. “You can probably use 80 percent or so. Even if it says the tank is full, we can’t use (some of it) depending on the temperature and the atmosphere.”

Don’t count on taking cross-country trips with a propane bus, either. With a very limited number of refueling stations and lower mileage, taking trips out of the Valley could be a hassle.

“From Toppenish, you probably couldn’t get to Seattle and back,” said Thorington. “We’d have to find a fueling station.”

Fortunately, Bleyhl Farm Service partnered with the district on a propane fueling station in Toppenish to serve the buses.

The main objective for Toppenish is to trim fuel costs. The district has already spent more than $90,000 on diesel in the 2013-14 school year; there are no projections yet on how much the district will save, but Thorington said fuel costs will go down.

There are no immediate plans to purchase more propane-powered buses, but that could change if the rollout goes well. Ideally, Thorington said they could replace half of the district’s 20-bus diesel fleet. Read more here.

Tuesday, June 17, 2014

Propane Powered Buses for Toppenish Students

Propane powered busses are set to start running this fall for the school district.

Yakima Valley diesel prices are beginning to rise above four dollars a gallon.

The Toppenish School District is planning to pay about half that with their new propane powered buses.

"After a government rebate our net costs of our propane is about a dollar-forty," says Blaine Thorington, Toppenish District Transportation Director.

The yellow buses are going green according to Thorington, who heads the Toppenish district transportation team and adds, "The exhaust coming out is clean, there's no black exhaust to have to deal with and they tell us that the oil when we dump it after an oil change is the same color, same texture as the new oil that goes in."

Thorington says these propane powered vehicles, or autogas, will be a "great barometer" for the district to see if the money they save is worth adding more.

The buses run using two large forty gallon tanks that are bolstered under the vehicle. While the high flamability of propane could be a safety issue, Blaine believes these buses are just as safe as any other in his fleet.

The large tanks are filled a couple miles away from the bus depot.

The company that builds these pump believes the fuel is much safer to handle as well, "It's a really good alternative fuel, it's used a lot in Eurpoe where they use mostly diesel, and ya i think it's a safer way to go," said Claude Zehnder, petroleum manager for Blehyl Farm Service.

Bus driver Rick Barber drove and fueled an autogas bus today, and says he is impressed and adds, "A lot more responsive, no engine noise, sounds just like a regular gas engine, nice and quite, pleanty of power to it."

Monday, June 16, 2014

Making the pitch for propane: Company focuses on fleets to build volume in effort to get the price of a system down

Via the Houston Chronicle (click for full article)
By Ryan Holeywell

Curtis Donaldson founded Georgetown-based CleanFUEL USA in 1993 after more than a decade working at Conoco (which became ConocoPhillips in a later merger). His company develops vehicle engines that run on propane - a component of natural gas - as well as propane fueling stations, primarily for fleets. It made news earlier this year when it entered a deal with UPS to supply the delivery company with 1,000 trucks and more than 50 fuel stations. He spoke with the Chronicle about the promise he sees in propane. Excerpts, condensed and edited for clarity.

Q: What prompted you to get into the propane business?
A: Conoco was looking at alternative fuels and putting them in our stations in the early 1990s. That was my project. I kind of got exposed to alternative fuels while working for a major oil company and fell in love with it. When Conoco decided not to progress beyond Denver, where the pilot project was, I left and started my own business to build dispensers.
The one thing I figured out for sure was customers aren't going to want to fill up with a device if it looks like something out of the ordinary. We build dispensers that look just like gasoline dispensers. Initially we were just making station equipment, then we migrated into making engines. Now, most of our business is on the engine side.
Q: What made you fall in love with propane?
A: I think two things. The idea of clean air quality drew me to it, and it's the utilization of a domestic resource.
Think about propane. It's in every town in America. There's no infrastructure cost to America to utilize propane. During the oil embargo (in the 1970s), propane grew from 1974 to 1981. We had 1.1 billion gallons sold by 1981, and 750,000 vehicles. I know we can do it. We've already done it once. Let's just do it again.
Q: The bulk of your customers are on the fleet side. What will it take for propane to catch on with private consumers?
A: In Europe, it's a consumer fuel. You can go to any dealership and order a propane vehicle. To get to that in the United States, we're starting with the fleets so we can build up the infrastructure of public fueling stations. It's the chicken and egg problem.
The other key is getting the volume up to get the price of the system down. Right now, based on a $10,000 propane system, who can economically justify the cost of converting? It's the fleets.
We start with fleets to build volume and infrastructure, and hopefully through building that volume, costs comes down. If we can get a system installed for $5,000, I think the consumer will start saying, "Wait a minute, I want some of that action."
Q: Why has the U.S. lagged behind the rest of the world in terms of using propane as a vehicle fuel?
A: If you look abroad, fuels in most countries are heavily taxed. In countries where propane has become prolific, the tax was waived for propane, or it's a minimal tax. In Poland about 30 percent of vehicles run on propane. Turkey's about 30 percent. Korea's about 25 percent. Australia's about 20 percent. In the U.S. we're about three-quarters of one percent.
 If we could just get to 10 percent there's enough supply that we wouldn't upset supply and demand economics.
Q: Are there any downsides to using propane in a vehicle?
Curtis Donaldson, managing director of CleanFUEL USA, shown with a company vehicle in a Houston parking lot in 2014, founded the company in 1993 to make propane-fueled vehicles and pumps to fuel them.
A: For fleets fueled in central locations, it's a no-brainer. The truck goes out and it comes back. But some trucks aren't centrally fueled. The drivers are wondering '"Where can I find propane?" I can show you where it is on a map, but how comfortable is the driver thinking he has to go out of his way?
Also, there's capital required. If they didn't put it into their budget this year, they have to put it in their budget next year. They have to spend $10,000 per vehicle to convert them. For fleets, it takes between a year and two years to pay off. But it doesn't change the fact that they need to have $10,000 per vehicle.
Q: How do you make your pitch to fleet managers?
A: If we can catch a guy who's already educated on alternative fuels, the cycle of sales is much shorter. You're just differentiating between other fuels at that point. But last week we were meeting with two fleets and it was raw education - Propane 101. We try to get them comfortable they're not jumping off a cliff with propane.
Q: If I'm a fleet manager considering alternative fuels, why should I use propane instead of compressed natural gas?
A: I'm for all energies being used.
I think the best use for CNG is in tractor-trailers and larger vehicles and mass transit. You can put a bunch of tanks on there, where the frame will support multiple tanks to get enough fuel on board.
I believe propane owns medium-duty down through light-duty. We're a liquid fuel. My pitch is we can range better, and range more closely to gasoline because we're a liquid. We're abundant. We're in every town. And the cost of infrastructure is less - about a tenth of what a CNG station costs.

Thursday, June 12, 2014

Thomas Built to hold tech training program in Dallas

The Thomas Built Institute Service Training – West will be held Sept. 9-12 in Dallas.

Thomas Built Buses officials said that the technician training program will enhance bus technician skills and complement school bus maintenance programs.

“We know how tough it is to keep up with ever-changing technology, EPA standards and safety regulations,” said Mike Stotler, service education manager for Thomas Built Buses. “The annual Thomas Built Institute has become a very popular opportunity for school bus technicians to get hands-on training and a factory-certified curriculum in small classes, all in less than a week’s time.”

Participating technicians select the track they want and receive 28 credit hours of continuing education.

The 2014 curriculum includes:
• An introduction to propane
• 2014 emissions systems
• Advanced electrical
• Coolant, maintenance and cost savings
• Utilizing websites, resources and wire diagrams
• Wheelchair lifts and seats
• A choice of one of the following tracks: Type C: multiplex, service link and troubleshooting; or Type D: electrical and fan drive

The cost is $325, which includes lunch and ground transportation.

Thomas Built officials said that classes fill up quickly, so early enrollment is recommended. Registration is limited to 100 participants to ensure small classes and personal attention. To register, go here.

Tuesday, June 10, 2014

PERC: Autogas Maintenance Gains

Beyond fuel cost savings and reduced emissions, “It’s equally important to consider the ease and operating costs before making the switch,” PERC says. “Parts, service, repairs, and garaging are important considerations that can have a big impact on ROI and a fleet’s success.”

The association is circulating information about the maintenance advantages of propane autogas as experienced by three different school bus operators. “Each,” PERC says, “found that maintenance with propane autogas has an advantage when compared with conventional and other alternative fuels that go well beyond the pump.”

PERC notes that the following data reflect each school district’s personal experience, and that factors may vary when compared with other fleets.
As related to Fleets & Fuels by PERC,

Tippecanoe Schools Corp, Lafayette, Ind.
Tippecanoe School Corp was formed in 1962 as one of Indiana’s largest geographical school districts, with 19 schools covering 465 square miles. TSC currently owns 160 school buses, including five 78-passenger propane-powered Blue Bird Vision Type C school buses they purchased in spring of 2012. Equipped with Roush CleanTech propane autogas fuel systems and Ford 6.8-liter engines, the buses have delivered top-of-the-line performance.

“Overall, it’s been very simple and we’ve only had to perform routine maintenance on the propane-autogas-powered buses,” said TSC’s Certified Master Truck Technician Alan Fidler, recognized as America’s Best Service Technician in 2011 and 2012. “It’s been much easier than working with diesel because of all the emission controls on new diesel engines, which seem to have a lot of problems.”
Compared with their diesel buses, TSC has noticed significant cost savings with propane autogas on routine maintenance such as oil changes and fuel filters. Fidler reports using 32 quarts of oil per oil change with their International and Cummins diesel engines versus only seven quarts with their Roush CleanTech propane autogas engines. In addition, diesel engines call for two fuel filters that cost $40 each while propane-autogas-powered buses use a single filter that costs substantially less.

Far Fewer Oil Changes, and No Additives
“In sum, the school district could change the oil in a propane bus almost five times before matching the price of what it costs to change the oil once in the diesel bus,” Fidler said. “When you tally the cost of oil and what we spend on fuel filters, the savings really add up with propane autogas.”

The school district also has to contend with the cost of fuel additives with diesel during winter months. When the temperature drops, gel from diesel thickens and runs the risk of gumming up the engine. Propane, on the other hand, requires no additives and is ready to go in any temperature or climate.

“You have to either blend your diesel fuel with kerosene to avoid gelling, which can add up to $3,000 to $5,000, or you have to use an anti-gel,” said Filder. “The kerosene has a tendency to dry up the diesel, but if you don’t blend, the anti-gel is even more expensive and can put the bus out for a longer time period. We don’t have these issues with propane.”

Training Was Very Simple
Years ago, Fidler worked on a propane-powered bus with an old vapor system. He recalled it having a bit of trouble starting up in the winter months, but propane engine technology has since been improved upon.

“The new liquid injection systems are much different than the old systems,” Fidler said, “If I had any apprehension about the district purchasing new propane-autogas-powered buses at first, it was because I was worried about their performance in the winter. But the new buses start right up in the cold unlike the old propane technology, and actually have an advantage of warming up a little bit quicker than our conventional diesel buses do.”

All of TSC’s maintenance technicians went through training before operating on the vehicles in order to learn how the Roush CleanTech fuel injection systems work and how to drain the tank in order to change the fuel pump. However, Fidler notes that the training was very simple, and he liked that the district did not have to make any adjustments to garaging or maintenance facilities to accommodate the alternative fuel.

“We service both our propane and diesel buses in the same area,” Fidler explained. “We didn’t have to add any special equipment or make any adjustments to the maintenance shop for the new propane autogas buses. It was a very turn-key process.”

Portland Public Schools, Portland, Ore.
Portland Public Schools, a leader in alternative fuel transportation, has been using propane autogas for more than 30 years. In 1983, the school district first converted three Thomas Built Type C buses with CleanFuel USA propane autogas fuel systems. Thrilled with the fuel’s obvious benefits — clean, cost effective and maintenance friendly — PPS has since contracted with First Student to convert an additional 52 propane-autogas-powered school buses in addition to their 45 gasoline buses.

“We were one of the first districts in the nation to order the newer liquid injection buses straight from the factory. We were sort of the guinea pig,” explains Eric Stewart, lead mechanic at PPS. “We’ve got things down now. It’s much easier to maintain these buses today than it has been in the past. Liquid injection propane autogas buses can be serviced at dealers now and maintenance is much simpler.”
PPS has seen a visible difference between gasoline and propane autogas fuel systems when preforming regular maintenance in the shop. Compared with gasoline, propane autogas is a much cleaner fuel.

‘You Could Extend Your Maintenance Intervals’
“When I go to change a propane autogas fuel filter, it comes out tremendously cleaner than the gasoline filters. It’s a difference you can actually see.” Stewart said. “If you weren’t concerned with the factory warranty, you could extend your maintenance intervals with the propane buses and save on oil and filters significantly.”

Much like TSC, PPS did not make any changes to its maintenance facilities when it switched to propane. In fact, Stewart says the maintenance techs have noticed another green benefit of the fuel: fewer exhaust fumes in the shop.

“Gasoline fumes can really choke you out of the shop if you don’t direct them outside. When working on a propane autogas bus, this isn’t necessary because the exhaust fumes inside the shop aren’t as harmful due to the fuel’s clean-burning properties,” said Stewart.

Give It a Try
Stewart has been with PPS for the last eight years working with both gasoline and propane autogas. When asked what advice he’d give to other fleets looking to add alternative fuels to their fleet, he stated that with new technology and improved dealer services on the buses, there’s no reason for districts to not give propane a try.

“You can’t go wrong with propane autogas,” Stewart said. “The simplicity and ease of the fuel is great, and it’s so similar to gasoline that you really don’t have to change the way you do things. After switching to the liquid injection technology, the power and start-up is no different than gasoline. If you got behind the wheel of one, you would never be able to notice a difference.” Read more here.

Thursday, June 5, 2014

Propane Autogas Stakeholders Convene for Engine Fuel Summit



Propane Autogas For Fleets: Study Identifies Some Key Considerations

The Mississippi Propane Gas Association (MPGA) recently commissioned a study conducted by the Stennis Institute at Mississippi State University that found propane autogas offers "numerous benefits" as a fleet fuel versus gasoline and diesel. The study also looked at the challenges fleet managers might encounter when considering autogas.

The researchers approached their work with an awareness of how propane has fit into the larger alt-fuel vehicle sector in recent years. "Over the last decade, the number of propane vehicles in use has incrementally declined, creating the impetus for inquiry into the reasons propane has declined in use, potentially, and whether propane should be considered as an alternative fuel for fleet vehicles," the report states.

The examination sought to investigate the viability of the fuel itself relative to gasoline and diesel, the state of refueling infrastructure, the availability of propane vehicles in the market, and other considerations. Among the key benefits that the researchers uncovered was autogas' fuel-cost advantage over petroleum-based fuels - although, like gasoline, diesel and natural gas, the price of propane varies widely region to region and state to state. Propane can also be purchased under long-term contracts that provide fleet owners with both bulk-pricing discounts and price stability.

Another important benefit is the greater availability of propane refueling infrastructure relative to other alternatives fuels. Using Mississippi as an example, the researchers noted that there are currently 124 public and two private propane stations in the state, according to the U.S. Department of Energy. (The MPGA counts more than 240 - a discrepancy that is likely attributable to the fact that alternative fuel stations self-report their operations to the DOE on a voluntary basis.)

The study also found that even if public propane refueling infrastructure is not available, stations can be built "with a minimal cost, when compared to other fuels." A 2010 report from the DOE, for instance, found that a typical propane refueling station could be developed for $37,000 (500-gallon tank and a single dispenser) to $60,000 (2,000-gallon tank and a single dispenser).

"Much of this infrastructure cost can be amortized within the fuel price itself through lease agreements with propane suppliers," the report says. "This possibility places the infrastructure considerations for propane in a class of its own, at least in the majority of the alternative vehicle fuels market."

Among the areas where autogas is potentially soft as an alternative to gasoline and diesel is the relative lack of vehicle availability. "Many of the previously existing propane vehicles from the 1990s have been retired, reducing the number of available vehicles running propane," according to the Stennis Institute.

The study also identifies issues such as vehicle conversion costs, propane-fuel price volatility and access to autogas refueling vs. gasoline and diesel as areas that fleet managers will need to weight against the benefits of propane.

The Stennis Institute ultimately concludes that propane autogas "should be considered when planning a conversion of a vehicle, or vehicle fleet, to alternative fuel vehicles."

"Propane, while not necessarily intended for large refuse trucks or heavy-duty applications as the primary source of fuel, is perfectly suited for light- and medium-duty vehicle fleet applications," the report states. Read more here.