While diesel prices have remained at a reasonable price over the past year, manufacturers are still evaluating various alternative fuel options. Fuel prices are volatile, making it necessary to continue investigating potential fuels so as to be prepared when prices rise again.
Many cities have also announced they will be limiting, if not prohibiting completely, the use of fossil-fuel powered vehicles within city limits over the next decade, further increasing the need for alternative fuel development.
Though alternative fuel use is not a new concept, its development and use has been growing in recent years. The applications in which it can be used has been expanding, as well, making it possible for a variety of vehicle and machine types to achieve the emissions-reduction, cost and other benefits alternative fuel use can offer.
Earlier this year, companies such as Kenworth and Toyota announced investigation into hydrogen as a potential fuel option for heavy-duty trucking applications, specifically Class 8 trucks. Read the article “Hydrogen Proves its Potential in Heavy-Duty Applications” to learn more.
Due to the growing interest in various alternative fuel options, the U.S. Dept. of Transportation’s Federal Highway Administration (FHWA) announced last year that 55 routes in the U.S. will serve as the basis for a national network of “alternative fuel” corridors spanning 35 states. Along these routes new signage will be put up to alert drivers about the location of alternative fuel stations. The network is currently 85,000 miles long, and the FHWA plans to add more miles in the future to accommodate electric, hydrogen, propane and natural gas vehicles as more refueling and charging stations are built.
Natural gas
Natural gas is available in many forms—compressed natural gas (CNG), liquefied natural gas (LNG), etc. As it occurs naturally underground, it offers an opportunity for countries such as the U.S. to use a domestic fuel instead of one from a foreign entity, helping to keep its cost low.
Though it is not a 100% clean fuel, it does offer many emissions and cost reduction benefits in comparison to diesel. It is also seen by many as a stepping stone along the path to other, more environmentally friendly fuel options.
In June of this year, NGVA Europe (the European Natural & bio Gas Vehicle Association) released a study which found natural gas reduces greenhouse gas (GHG) emissions on a Well-to-Wheel basis in heavy-duty applications by 16% for CNG and up to 15% for LNG compared to diesel. In addition, the study said the use of renewable gas (i.e. biomethane) provides further benefits towards carbon-neutral mobility; when natural gas is blended with 20% renewable gas, it can reduce GHG emissions by 40% compared with oil-derived fuels.
Due to the many benefits it does offer, and its ability to be used in many heavy-duty applications, its use in the U.S. has been growing in recent years. ACT Research reported in May that natural gas Class 8 truck sales started 2017 off on a strong foot as refuse, transit and school bus fleets have increasingly adopted use of the fuel. 
The FPT NES 6 NG engine can operate on biomethane to achieve up to zero carbon dioxide emissions output.FPT Industrial
As its popularity has grown, particularly in the heavy-duty truck market, many manufacturers have introducing engines and vehicles that operate on natural gas. Frost & Sullivan reported in February that by 2025, one in 10 medium- and heavy-duty trucks sold will run on natural gas. "Compressed ignition engines with high-pressure direct injection (HPDI) technology are gaining traction and are expected to garner wide OEM support to reach sizeable scalability by 2025," said Frost & Sullivan Mobility Industry Analyst Saideep Sudhakar in a press release announcing the company’s new report. "The NG [natural gas] market is witnessing the first wave of consolidation across integrators and tank manufacturers. Japan, Russia, India and Indonesia are emerging as the next big adopters of NG vehicles."
Cummins Westport Inc. introduced its model year 2018 near-zero emission natural gas engines in May. According to the company, the ISX12N and L9N models are the lowest certified nitrogen oxide (NOx) emission engines available in North America; their NOx exhaust emissions are 90% lower than the current EPA limit. All of the engines have the option of using CNG, LNG or renewable natural gas (RNG).
FPT Industrial’s NEF 6 NG engine, which made its debut at EIMA 2016, has the ability to operate on biomethane, as well, which the company says helps it achieve up to zero carbon dioxide (CO2) emissions output.
DME
Earlier this year, a customer demonstration began of a DME-powered Mack truck was announced. Dimethyl Ether (DME) is a clean-burning fuel provides the same performance as diesel but burns cleanly without producing any soot. And when produced from local organic waste, it can reduce GHG emissions by 68-101% compared to diesel.
Mack Trucks partnered with Oberon Fuels on the development of the DME-powered Class 8 Mack Pinnacle which is being tested by the New York City Dept. of Sanitation (DSNY). Oberon is the first company to bring fuel-grade DME to market. The small-scale production of the fuel it has developed allows a smaller volume of feedstocks that typically go unused to be utilized in the production of the fuel. Usable feedstocks include shale gas, and biogas from animal, food and agricultural waste. 
A Class 8 Mack Pinnacle operating on DME underwent testing by the NYC Dept. of Sanitation during the first quarter of 2017.Mack Trucks
Mack Trucks’ sister company Volvo Trucks North America first announced a partnership with Oberon in 2013 as part of its alternative fuel strategy. It chose to focus efforts on this fuel source—after testing several different ones—as it met the performance characteristics it was looking for, as well as emissions reduction goals for both CO2 and GHG emissions.
The project with DSNY will involve use of Oberon’s catalytic distillation technology which enables production units to be placed near local feedstock sources, so cities like New York can deal with both their waste and energy challenges by doing everything locally. This further aids emissions output as the fuel does not have to be transported long distances to user.
Propane
Propane’s use within the heavy-duty equipment industry continues to expand beyond the commercial mowing and bus segments where it is most notably utilized. Jeremy Wishart, Deputy Director of Business Development at the Propane Education Research Council (PERC), says one of the key things the organization does is invest in technologies and market development opportunities beyond the ones in which it has traditionally been used. “It’s been a multi-tiered, multi-market effort to show customers propane applications, and build their awareness and comfort levels beyond the traditional uses of propane,” he says.
About 10 years ago, PERC started targeting what Wishart calls the light and medium portion of the heavy-duty vehicle and equipment markets, basically Class 7 and below. This market segment began to pick up momentum, he says, when Power Solutions International (PSI) introduced its 8.8 L propane autogas engine back in 2014. The engine is designed to provide diesel-like power and performance, producing 270 hp at 2,600 rpm and up to 565 lbs.-ft. of torque.
Wishart says the engine was targeted at the Class 7 delivery truck market, particularly to provide a diesel alternative for trucks delivering propane. “They [fuel providers] primarily wanted something that could deliver their product – propane – to a customer utilizing the fuel they’re taking to them.” Transporting propane to a customer using a diesel-powered truck made some customers question why it was beneficial for them to use the fuel if the company they were getting it from wasn’t even using it. “Now [fuel providers] have that opportunity with several propane-powered options to deliver propane,” he says.
Since its release, Wishart says the PSI engine has started transitioning to other applications. One such application is terminal tractors. In 2016, PSI partnered with TICO to integrate the 8.8 L into TICO’s Pro-Spotter terminal tractor. In March of this year, the company’s announced they would integrate a CNG version of the PSI 8.8 L into a new prototype terminal tractor being tested by TICO. "The increasing costs and complexity associated with meeting diesel emissions is helping the shift to offer gasoline and alternative fuel engines," said Frank Tubbert, TICO General Manager, in a press release announcing the new project. "This collaboration reflects that shift. We also wanted, in large part, to offer the customer more choices and to focus on clean air as a major policy objective." 
The PSI 8.8 L propane engine.Power Solutions International (PSI)
Seeing the growth potential of propane in various markets, Agility Fuel Solutions announced in May the establishment of a new Powertrain Systems business unit. It will initially focus on the development, certification and integration of low-pressure propane fuel systems for use on OEM engines and vehicles. "The most important step the transportation industry can take toward a healthy planet is replacing diesel with clean fuel. For some fleets the best choice is natural gas, for others propane. Agility now offers an even broader portfolio of clean fuel solutions for our customers," said Kathleen Ligocki, Chief Executive Officer in the press release announcing the new division.
Propane can offer both economic and environmental benefits. Though it varies by application and duty cycle, on average propane-powered equipment can provide a 30-50% lower operating cost, says Wishart. It also offers reductions in fuel evaporation, theft and spillage, which he says all contributes to a fleet’s bottom line. In addition, propane does not have the fuel contamination issues often experienced with ethanol and gasoline, nor does it experience gelling in cold climates as diesel does. For off-road applications, this is particularly beneficial as the equipment may not get used every day and thus cause start-up issues.
On the environmental side, he says propane emits 15% less GHG and 40% less carbon monoxide.
Todd Mouw, Vice President of Sales and Marketing at ROUSH Clean Tech, also notes that because propane is liquid and portable, it can be stored onboard a vehicle in a comparable amount to diesel without compromising load capacity. He says the technology is easier to maintain, as well, as there is no aftertreatment system on the engine.
In order for the propane market to progress, Mouw says it will be necessary for the industry to continue innovating as the company did with the introduction of its propane engine for Class 4-7 vehicles. The engine is Environmental Protection Agency (EPA) and California Air Resources Board (CARB) certified to the optional low NOx level 0.05 g/bhp-hr, making it 75% cleaner than the current emissions standards.
“We continue to invest in our supply chain and we believe this will further strengthen our foundation and give more customers the confidence to make the change,” he says. “Propane infrastructure is relatively easy and inexpensive, so that should not be an inhibitor to seeing the growth accelerate.
“Ultimately, human nature is resistant to change. But with propane autogas, we have a domestic, value priced, clean and abundant energy source that will allow operators to reduce operating cost without compromising the asset from a performance and durability perspective,” says Mouw. “We believe there will be strong demand signals from the market as we get more Class 6-7 operators seeing the results and wanting that to extend into their larger, Class 8 equipment.”
This is of course by no means a comprehensive list of all the alternative fuels in development and use today. But it does provide a picture of the variety of fuel options available, which is beneficial as not all fuels are suited for all applications. Having multiple options ensures there is a fuel that best meets each individual application’s specific needs, and better aids the transition away from fossil fuel use.
