When to switch to natural gas engines

Red, yellow and white buses driving down a highway

Natural gas engines can be a great option for commercial vehicles. They’re quieter than diesel engines, they reduce air pollution, and they can help fleets save a lot of money on operating costs, especially when it comes to fuel. So why don’t more fleets switch to natural gas engines?  

Compressed Natural Gas, or CNG engines are a great option for a wide range of fleets and commercial vehicle applications, but not all.  

Are natural gas engines a good fit for your business or mission profile? We'll lay out some of the key benefits of natural gas engines, and some of the drawbacks, to help you decide where natural gas is a viable option for your fleet. 

Mission profile and Infrastructure while switching to natural gas engines 

Given the current state of natural gas refueling infrastructure availability, fleets seeing the most success with CNG today are those that return to base each night. These are fleets that can complete their routes on a single tank of fuel, return to base and refuel “behind the fence.” 

At the end of their shift, drivers park their vehicle in a designated space. They connect a fueling nozzle to the vehicle and go home. The next day, the tank is full. Transit buses, refuse trucks, urban delivery trucks, and regional haul semi-trucks are all good examples of vehicles that can effectively refuel at a central depot. The behind the fence refueling system works well for these applications. 

There are set-up costs associated with establishing refueling capacity onsite, but most natural gas fuel suppliers offer options to install fuel pumps with no money paid upfront. The cost is baked into the fuel contract, which can be as long as a three-year term. This provides stable fuel costs over the life of the contract and the savings are significant compared to the high cost of diesel fuel, which is much more volatile. 

For heavy, or long-haul trucks, refueling is more difficult. They rely on public refueling stations along major interstates. Currently the number of public CNG pumps is dwarfed by the number of diesel pumps, but Cummins and several transportation industry partners are making strides to change that. The company recently announced a plan to collaborate with Love’s Travel Stops and Trillium to enhance low and zero carbon fuel and powertrain solutions.  

Cummins also recently announced plans to develop a 15-liter natural gas engine, the X15N, designed for class 8 long-haul applications. News of the X15N is already generating significant interest and excitement in the North American heavy-duty truck market. So much so it was named one of the Top 20 New Products of 2022 by Heavy Duty Trucking (HDT). 

These investments in new products and refueling infrastructure will make integrating natural gas vehicles easier for long-haul fleets.  

Maintenance and safety considerations for natural gas engines 

In addition to considering refueling needs, there are unique maintenance needs that should be considered.  

CNG systems have three main hazards: high pressure, fire and asphyxiation. High pressure is the primary concern because the nominal fill pressure of the CNG stored in fuel tanks is 3,600 psi. To address high-pressure concerns, non-CNG cylinder components in the high-pressure CNG fuel system are designed to withstand at least 14,400 psi without bursting, four times their rated pressure.

CNG cylinders are built to meet rigorous federal standards and are constructed from much sturdier materials than gasoline or diesel fuel storage tanks. All CNG fuel cylinders must be manufactured to withstand 2.25 times their fill pressure. This means that all CNG cylinders have a minimum burst pressure of 8,100 psi which is far above the fuel delivery pressures of CNG fueling stations. 

To prevent CNG cylinder rupture during fire or over pressurization, pressure relief devices (PRDs) are installed. These devices open at specific temperatures or pressures, releasing the cylinder's pressurized contents. Each cylinder is equipped with at least one of these mandatory safety devices—and many cylinders have two or more PRDs. 

Not every maintenance facility can be used for CNG vehicle maintenance. Facilities that support vehicles using liquid fuels incorporate several safety features that differ from the safety requirements needed to service natural gas trucks.  

For example, indoor facilities that service diesel trucks have ventilation systems designed to capture fuel vapors near ground level because liquid fuel vapors are heavier than air. The components of natural gas are lighter than air and rise to the ceiling. That means CNG maintenance facilities require sensors and ventilation systems at ceiling level to alert technicians is potentially dangerous. The shops must also be certified by a fire marshal for proper ventilation, which is uncommon when compared to other traditional shops. In addition to proper ventilation, CNG service facilities need to have methane detectors.  

It’s critical that CNG vehicles are serviced according to the manufacturer’s recommended maintenance intervals. This includes making sure oil changes are performed on time, using a schedule based on operating hours. It is also important to use the proper engine oil. Cummins natural gas engines use a different oil specification compared to their diesel counterparts. In 2018, Cummins announced a new oil specification — Cummins Engineering Standard (CES) 20092—that allows for longer drain intervals. 

If you’re thinking about setting up a natural gas fueling point or about maintaining natural gas vehicles on your premises, it’s a good idea to estimate the cost of these modifications. When they are low, the economic benefits of natural gas engine powered vehicles can surpass these switching costs. 

Role of natural gas engines in reaching environmental goals 

Switching to natural gas engines is a top choice for commercial vehicle fleets to reduce NOx, particulate matter, and VOC emissions, while also enjoying other environmental sustainability benefits.

Reducing emissions, however, does not have the same air quality benefits for every vehicle. Trucks used on lightly traveled roads in sparsely populated areas may not have a significant impact on air quality locally. They’re also unlikely to cause a significant degradation. If the same truck was on drayage duty between the port of Los Angeles and logistics centers in the area, its emissions would be more likely to contribute to local air quality concerns. 

This is why companies that operate vocational vehicles in urban areas may want to consider using natural gas engines. Switching to natural gas benefits the communities in which these businesses operate. Their customers, who often belong to those communities, stand to benefit the most from better air quality. 

Regulations to consider while switching to natural gas engines 

Reducing emissions is a great way to generate goodwill among the community, but sometimes it’s also a matter of compliance. In some areas, strict emission standards apply to both the sale of new vehicles and to in-use vehicles. California, for example, enforces a set of rules applicable to heavy-duty diesel vehicles.  

As a result of these rules, starting in 2023, all drayage trucks using diesel engines will require a 2010 or newer engine. For businesses replacing trucks or engines, switching to natural gas is a cost-effective way to meet emissions standards and save on fuel expenses.

Both the Environmental Protection Agency (EPA) and California Air Resources Board (CARB) have tighter emission regulations coming in 2024 and 2027. The Cummins X15N will be certified to not only meet these emission requirements, but to exceed them as well, ensuring compliance for years to come. 

In summary, natural gas engines can help fleets lower their total transportation emission and slower operating costs without major disruptions to their day-to-day operations or mission profile. Moreover, natural gas, as a fuel, has a key role to play in our renewable future.  

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Puneet Singh Jhawar

Puneet Singh Jhawar

Puneet Singh Jhawar is the General Manager of the global natural gas business for Cummins Inc. In this role, he is responsible for the product vision, financial management and overall performance of the natural gas business. Over his 14-year career at Cummins, Jhawar has cultivated successful relationships with a number of Cummins’ largest customers. Jhawar has extensive global experience, with roles based in the Middle East, India, Europe and the US.

Unpacking CARB’s trucking rules, regulations and legal challenges

Semi truck driving

The state of California has positioned itself as a central figure in a revolutionary shift from a 100-year path of internal combustion engines (ICE) used in commercial transportation. Within a three-year span, the state has adopted the world’s most stringent commercial vehicle regulations: Advanced Clean Trucks (ACT), the Heavy-Duty Engine and Vehicle Omnibus Regulation and Advanced Clean Fleets (ACF). The three rules work together to gradually transition commercial trucks, buses and vans to zero emission vehicles (ZEVs).

The stringent regulations have generated plenty of praise, collaboration, concern and even legal challenges. Turning away from familiar and trusted technology will be anything but easy but the industry is proving it is possible.

Questions around ZEV cost and capability relative to ICE are not taken lightly by Cummins nor other players in one of the nation’s most critical industries.

As with prior emissions legislation, amendments will undoubtedly emerge as collaborative efforts between policymakers and industry continue. That is currently the case with the Omnibus regulation as proposed amendments are under review by the Environmental Protection Agency. Some of the amendments in question focus on diesel engine testing, warranty periods and aftertreatment. 

“Omnibus, the amended version, got resubmitted to EPA and is calling for increased legacy allowances,” explained Tom Swenson, Director of Global Regulatory Affairs.

Emission legislation passed by the California Air Resources Board (CARB) requires a Clean Air Act waiver from the EPA when it proves stricter than federal policy. CARB has been receiving federal waivers for its emissions policies since the 1960s given its ongoing battles with air pollution.

Geographical features such as valleys and mountains appearing throughout the state can hinder air circulation to keep pollutants hanging around.

“The San Joaquin Valley in California, for example, is like a little trap of NOx,” Uma Vajapeyazula, North American Market Strategy Director, described.

Eager to overcome its unique air pollution issues, CARB has kept a close eye on ZEV development. Once board members decided the technology was up to the challenge of replacing ICE trucks up to Class 8, CARB adopted the Advanced Clean Trucks (ACT) rule in June of 2020. To date, it’s the only one of the three ZEV polices that has received an EPA waiver.

 The ACT rule requires that manufacturers who certify chassis or complete vehicles with a gross vehicle weight rating (GVWR) greater than 8,500 lbs. sell zero-emission vehicles (ZEV) at an increasing percentage of their annual California sales starting with the 2024 model year. The annual reporting began with the 2021 model year.

 OEMs struggling to sell ZEVs can buy ZEV credits from other manufacturers to unlock sales of their ICE vehicles. However, there’s concern that funds used to purchase ZEV credits could impact their bottom line.

 “One question is, ‘Will ZEV credit trades happen between competitors?’” Swenson said.

In September 2021, CARB adopted the Heavy-Duty Engine and Vehicle Omnibus Regulation to “drastically cut smog-forming nitrogen oxides (NOx) from conventional heavy-duty engines. The Omnibus Regulation will significantly increase the stringency of NOx emissions standards and will also lengthen the useful life and emissions warranty of heavy-duty diesel engines for use in vehicles with a gross vehicle weight rating (GVWR) greater than 10,000 pounds. The more stringent NOx emission standards begin with the 2024 model year engines and become more stringent with 2027 and subsequent model year engines.”

 Extending warranty coverage will necessarily increase the cost of equipment, Swenson noted.

 Advanced Clean Fleet legislation rolled out next in April 2023. ACF requires fleets to gradually replace acquired ZEVs while allowing them to retain ICE vehicles throughout their useful life. Per CARB, useful life is defined “as the later of either: 1) 13 years, beginning with the model year that the engine in the vehicle and was first certified for use by CARB or United States Environmental Protection Agency (U.S. EPA), or 2) the date that the vehicle exceeds 800,000 vehicle miles traveled or 18 years from the model year that the engine in the vehicle was first certified for use by CARB or U.S. EPA (whichever is earlier).”

ACF compliance challenges

In August, EPA held an ACF waiver hearing that included a full day of testimony, comments were also accepted online. One of the companies to participate was Sundance Stage Lines in San Diego. The charter bus company currently uses diesel-powered custom-built buses with a 1,000-mile range and 20-minute refueling time. It has stated opposition to ACF’s zero-emission mandate.

“As BEVs, range is cut to approximately 200 miles (substantially less in cold weather), at which point the vehicle requires a four-hour charge at a dedicated high-voltage charger before it can proceed another 200 miles,” Sundance Stage Lines writes. “Thus, any group attempting to access an area not serviced by either an airport or a nearby charter operator will be forced to make other arrangements. This will have substantial negative effects both on motorcoach operators and the traveling public.”

Among the concerns expressed, Sundance noted that “four major motorcoach manufacturers offer at least one of their models as battery-electric vehicles (BEVs.) In converting the vehicle to run as a BEV, all of the buses have lost over 70% of luggage space because the volume of batteries needed to give the vehicle a reasonable range requires the batteries and the accessories normally driven by the engine be mounted in the underfloor luggage compartments.”

Sundance also pointed out the high cost of ZEVs versus ICE. In the case of motor coaches, the company contends the price “more than doubles, from $650,000 each to over $1,400,000 per bus - a cost per unit over twice as high as any other electric vehicle.”

In its ACF waiver request submitted last November to EPA, CARB writes that “anticipated developments will likely both reduce the costs and increase the number of commercially available ZEVs, including projected decreased costs of batteries and improvements in battery energy density due to economies of scale and increasing pace of technology development and decreased costs of other ZEV components resulting from the projected increased production of ZEVs.” 

Legal battles persist

At least three lawsuits that have emerged to challenge the enforcement of ACF make it California’s most contentious trucking legislation to date. 

The first complaint was filed in October 2023 by the California Trucking Association in the U.S. District Court for the Eastern District of California. The challenge has resulted in the state holding off full enforcement that was originally slated to go into effect on January 1, 2024. CTA’s 32-page complaint argues that the state needs a waiver from the Environmental Protection Agency prior to enforcing ACF since its policies exceed federal mandates.

In response, California put ACF enforcement on hold for most fleets pending receipt of an EPA waiver. CTA noted on its website that waivers typically take 9-12 months to process. The state has been enforcing ACF for public fleets since applying for the waiver in November

“They’re implementing and enforcing ACF for state [California] and local government fleets,” explained Mari Mantle, Cummins Regulatory Affairs Manager. “It's the high priority, federal and then drayage [fleets] that they're waiting on the waiver for.”

CTA’s complaint also highlights concerns of ZEVs relative to internal combustion. Acquisition costs of ZEVs, according to CTA, are “projected to be 2 to 6 times higher than comparable ICE tractors”; ZEV range “is less than half that of an ICE truck”; additional refueling stops needed for ZEVs will require additional time and infrastructure and thus limit more route options historically utilized by ICE trucks.

In April, American Free Enterprise Chamber of Commerce (AmFree Chamber) and Associated Equipment Distributors (AED) filed suit also challenging California’s ACF regulation.

In May, the Nebraska Trucking Association topped a list of plaintiffs that included seventeen states opposing ACF: Alabama, Arizona, Arkansas, Georgia, Idaho, Indiana, Iowa, Kansas, Louisiana, Missouri, Montana, Nebraska, Oklahoma, South Carolina, Utah, West Virginia and Wyoming. Several of these same states joined a suit last year against the Advanced Clean Trucks rule.

Tom Quimby headshot

Tom Quimby

Tom Quimby, On-highway Journalist, has a broad range of experience covering various topics for local and national periodicals. His stories and photos have appeared in The Washington Times and more recently in Commercial Carrier Journal, Overdrive, Hard Working Trucks, Equipment World and Total Landscape Care. Tom has reported on Class 1 – 8 commercial vehicles since 2015. A graduate of the University of Southern California, Tom enjoyed growing up around hot rods, dirt bikes, deserts and beaches near San Diego. He now calls Northwest Florida home.

STEM Project Unites Children in the UK and Uzbekistan

Zoom call with West Park School and the Children's Home

If you ever doubted the ability of young minds to grasp what many adults would consider complex concepts, then you'll be amazed by the achievements of two groups of young children - one in a school in northern England, and the other 4,000 miles away in an orphanage in Uzbekistan.

With the support of Cummins, children ranging from six to twelve years of age have managed to bridge the language, culture, and time divide. They are collaborating with great success on building a basic electric racing car.

The story begins with a visit by Cummins to Rudmash Export Service, which has been representing Cummins in Tashkent, the capital of Uzbekistan, since 2018.

Rudmash has an impressive list of clients in mining, construction, gas, and power generation.

It is also a highly respected supporter of community initiatives, a key focus for Cummins.

During the visit, Amit Kumar, Cummins' Technical Territory Manager for the Commonwealth of Independent States (CIS) region, mentioned the work he was doing with local schools involving the Greenpower Education Trust in the UK.

Amit suggested that Rudmash might consider introducing local children to the fantastic learning opportunity that comes from building an electric car.

The Rudmash executive team loved the idea and reached out to their friends at the local orphanage (Children’s Home 22), about the proposed connection with children from West Park Academy – a primary school near Cummins' manufacturing plant in Darlington, England.

Students at the Children's Home working on the car
The children from Children's Home 22 building the car

Speaking through a translator, Rudmash Sales Manager Mr. Mavlonberdi Akhmedov said there was no hesitation from the orphanage. "Everyone was excited about it," he said. "When we showed them pictures of the car, the children's eyes lit up with interest.

"The only issue we encountered was not being able to involve the older children, but I think Amit has something in his mind for them. It will involve a similar collaboration with a UK school on a larger electric car that they can fit in!"

Over in Darlington, teacher Mr. David Fraser and his group of 9 to 11-year-olds were thrilled at the prospect of working with children from another country.

Students from West Park Academy
The children from West Park Academy

"Before our first session, I showed the children a map of Uzbekistan and explained how the time zones worked," Mr. Fraser said. "Tashkent is four hours ahead of us."

"When they started hearing a different language, they were a little hesitant although still excited. However, towards the end, once they got used to the translation pauses, lots of questions were being asked."

"They adapted very quickly, and every session with the orphanage has become more engaging. The children have greatly benefited from the relationship. It's been a great learning experience."

The car involved in the project is called the Greenpower Goblin G2. It comes as a flat-pack kit including chassis, wheels, steering, disc brakes, a 24V electric motor, and two 12V batteries.

Students at West Park Academy working on the car
The children from West Park Academy building the car

"The project is all about inspiring young children to take an interest in engineering in a fun and innovative way," said Amit Kumar, who earlier this year received special recognition at the North-East England STEM (Science, Technology, Engineering, and Mathematics) Awards for his years of dedication to STEM Education.

"The build introduces children to basic mechanics and electronics and might be the first step on the pathway to a career in engineering or another STEM field.

Mr. Fraser said the children soon started discussing aspects of the car such as frames, brakes, and steering geometry. There was a lively question-and-answer session on different materials that could be used to design and make the car's body. Their last session was about controls and driving.

"There are also other general discussions, as the children are eager to learn more about each other's countries," said Amit, who leads the sessions.

Students at the Children's Home looking at the car drawing
The children from Children's Home 22 talking about a drawing while on a zoom call

Rudmash service engineer Mr. Abdullayev Shakhzod said the children were enjoying the experience of working in teams.

"It's a fantastic new chapter in the history of a place that has a storied past. It was established in 1942 during the Second World War to care for evacuees from all over Eastern Europe. Children of over 40 different nationalities have been cared for by this children's home.

"The home is named Antonina Pavlovna Khlebushkina after the woman who ran it in the early days. She would be so proud of what is happening there today.

"As the summer vacation times differ in the two countries, the West Park school children have already finished building their cars, while the Uzbekistan car is about 40% complete.

"When the children return from their summer camp in September, they will start the rear axle, motor, and electrical components. Then they can take it for a drive," Amit said.

"Just before their summer term ended, the West Park children conducted a demonstration for their new friends in Tashkent. They set up a track and showcased driving the car on it. It was a great success."

Mr. Akhmedov, speaking through a translator, mentioned that the management team at Rudmash was considering how the project could expand beyond the children's home and into schools and youth organizations throughout Uzbekistan.

Mr. Akhmedov praised Cummins for their support of the project. "They have shown great responsibility at every stage and been very proactive, always striving to ensure things are done right.

"This is just the beginning for these children. It's already motivating them to learn more and develop their skills in broader technical applications.

"I would say that this project is not only important for the children's home but also for our city of Tashkent and the Republic of Uzbekistan, as it is nurturing an educational culture that is highly valuable. I can't thank Amit and Cummins enough."

Amit expressed that it's a privilege to help Cummins inspire young people about engineering and science from an early age.

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