Reducing your fleet’s emissions with natural gas engines

trucks and cars in traffic

There are many good reasons to switch to vehicles with natural gas engines, such as saving money on fuel and on vehicle, a better ability to forecast operating costs and avoiding cold-weather problems.  

Another top reason why many fleet operators invest in compressed natural gas (CNG) vehicles is that they can drastically lower emissions. The 2022 State of Sustainable Fleets Report found that 96% of surveyed CNG users consider CNG vehicles equal to or better than diesel and gasoline engines at reducing emissions. 

Why is it important to reduce emissions? 

Motor vehicles are an indispensable tool for many businesses. Unfortunately, they can cause air pollution and contribute to climate change. The right upgrades can reduce emissions of both greenhouse gases and common pollutants, which impact air quality locally. 

For some businesses, reducing emissions is a matter of being responsive to the needs of their customers. Garbage collection companies, for example, can improve their reputation in the communities they serve by operating cleaner and quieter trucks. Contracted school bus companies can differentiate by operating buses that don’t cause air pollution around schools at pickup time. 

Some companies also have broader environmental, social and governance goals that include a reduction of emissions. Though emission reduction upgrades have a cost, many public companies share the view that ESG progress increases shareholder value in the long term.  

In some cases, reducing emissions is a matter of compliance with environmental rules. The Port of Los Angeles, for instance, has strict emissions standards that drayage trucks serving the port must comply with. 

Why pick natural gas to reduce fleet emissions? 

There are several ways to reduce a vehicle’s greenhouse gas emissions. Using biofuels, for example, is a good way to make a vehicle’s operation more carbon neutral.  

There are also other ways to scrub a vehicle’s exhaust from NOx, particulate matter and other pollutants. Diesel vehicles fitted with a particulate filter and a catalytic converter, for example, can operate with minimal emissions. When you switch to natural gas engines, you can do both.  

Natural gas vehicles are a tried-and-true technology that has been around for decades. In the United States, about a third of all transit buses built each year run on natural gas. Beyond transit buses, there are many other examples of natural gas engines on trucks and buses. 

There are many benefits of natural gas engines in transportation. You can reduce your fleet’s emissions of common pollutants and cut the level of greenhouse gases. Natural gas also tends to be significantly cheaper than petroleum fuels, so there is an immediate economic benefit when adopting natural gas engines. 

Throughout 2021, CNG maintained a clear cost advantage and relative price stability when compared to the price volatility of diesel. CNG prices rose by approximately 3% on average at public fueling stations, while diesel prices increased nearly 19% nationwide, making CNG 25% more affordable on a DGE (Diesel Gallon Equivalent) basis. Consequently, fuel cost was a primary benefit of CNG users in the annual State of Sustainable Fleets survey, with 79% of respondents reporting lower costs as an advantage. 

What outcomes should you expect with natural gas engines? 

As you are upgrading a fleet of older vehicles, you can expect reductions in greenhouse gas emissions.  

A new transit bus equipped with a Cummins L9N natural gas engine, for example, will typically have 11% less well-to-wheels greenhouse gas emissions than an older diesel bus. (If the older bus is replaced with a new bus with the diesel version of the L9N engine, emissions would be reduced by only 6%). Replacing a medium sized fleet consisting of 100 transit buses with CNG buses can, on average, eliminate about 1,300 tons of CO2 emissions per year. That’s equivalent to taking 280 cars off the roads. 

If renewable natural gas (RNG) is used, the reduction of greenhouse gas emissions can be even greater. Renewable natural gas is manufactured primarily using methane that comes from the decomposition of organic waste. This can include landfill gas or methane captured from wastewater treatment facilities or agricultural waste. 

Using RNG brings the total carbon intensity score down, because RNG is made with methane that would have otherwise been off gassed. Capturing those gases prevents them from entering the atmosphere and reduces the total well-to-wheel score significantly. It can even drop the carbon intensity to below zero depending on the RNG feedstock. Renewable natural gas is functionally identical to natural gas obtained from fossil resources. Blending fossil natural gas with even small quantities of RNG can result in immediate environmental benefits. And every year RNG becomes a bigger percentage of all CNG being used in North America, contributing towards the role natural gas to play in our renewable future. 

It doesn’t matter why you’re considering integrating natural gas vehicles into your fleet. Cummins has a range of CNG engine options to get the toughest jobs done. 


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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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