NGV trucking outlook on the rise
Over-the-road (OTR) trucking presents a major opportunity to replace petroleum fuels with natural gas, along with the associated potential for reduced emissions and lower fuel costs. Historically, obstacles have included a severe lack of fueling points, unavailability of heavy-duty natural-gas-powered road tractors, and long payback times for adopters of the natural gas option. However, many of those obstacles have been overcome, and the benefits continue to increase.
Natural gas versus petroleum-based fuels
Environmental issues and cost are the major problems with petroleum-based fuels. “Large truck engines running on diesel are major sources of harmful pollutants, such as ground-level ozone and particulate matter,” said Brett Brown, manager of gas operations at Dominion Energy. “Natural gas is the cleanest alternative transportation fuel available and can provide particular benefits for ozone nonattainment areas. As a transportation fuel, natural gas can reduce greenhouse gas (GHG) emissions by 20% to 30% when compared with diesel and gasoline. Specifically, natural gas produces 70% to 90% less carbon monoxide, 75% to 95% less nitrogen oxides, 50% to 75% less nonmethane organic gas, and 20% to 30% less carbon dioxide.”
“With increasingly more stringent emission regulations, emission controls on diesel engines have become more complex with the addition of diesel particulate filters and selective catalytic reduction system, plus its associated diesel emission fluid,” said Tom Swenson, a business development leader (California), at Cummins Westport. “Both the California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (EPA) have indicated they will be considering promulgation of yet lower NOX standards. CARB has indicated it is looking at a NOX standard in the range of 0.02g/bhp.”
“What are the problems associated with petroleum-based fuels? I think the better question is why are OTR fleets drawn to natural gas? The answer is mainly lower operating costs (fuel cost and maintenance savings) and superior emissions/sustainability benefits,” said Daniel Gage, president, NGVAmerica (Natural Gas Vehicles for America). “Natural gas is traditionally cheaper and more stable in price.” Current pump prices are typically $0.75 to $1.00 lower than diesel, according to Gage.
According to Gage, diesel has a history of volatile price swings, much of crude oil is sourced from high-conflict regions, and commodity cost makes up 60% of the sales price. However, Natural gas has decades-worth of affordable domestic reserves, it is sourced from North America, and commodity cost makes up only 23% of the sales price.
Increasing fueling opportunities for OTR trucks
The infrastructure for refueling continues to develop. “An increasing number of truck stops and fueling stations around the country are in place to refuel large trucks including OTR freight trucks,” Gage said. “These include refueling stations operated by Loves, Clean Energy, Pilot/Flying J, ampCNG, American Natural Gas, U.S. Gain, and TruStar Energy CNG. There are 907 public fast-fill compressed natural gas (CNG) fueling stations in the U.S.; 722 of these stations can fuel heavy-duty trucks. There are 66 liquefied natural gas (LNG) public fueling stations in the U.S., all of which are capable of fueling heavy-duty trucks. Natural gas fuel is a proven, commercially-ready-right-now and road-tested technology. We have an established refueling infrastructure of more than 2,000 stations with a mature network of manufacturers, servicers, and suppliers coast-to-coast. And natural gas fueling pays into the Federal Highway Trust Fund.”
Dominion Energy’s Brown agrees. “Over the past five years, high-speed, high-volume CNG stations along major U.S. transportation corridors have been connecting major markets,” he said. Now we’re starting to see significant incentives to dispense renewable natural gas (RNG). On Jan. 1, 2019, the Utah, Public Service Commission approved a tariff for Dominion Energy to dispense RNG through its 24 CNG stations later this year.”
Fuel providers continue to expand the natural gas fueling network with contract carrier operators, which provides more flexibility to the routes available to natural gas trucks, said Hugh Donnell, a business development leader at Cummins Westport. “The U.S. Postal Service has been particularly supportive of its contract mail carriers’ use of natural gas trucks and we continue to see continually more of those routes being supported by natural gas as the network increases.”
CNG and LNG advantages and disadvantages
At fueling points, natural gas may be dispensed as CNG or liquid natural gas LNG. According to Brown, CNG is pressurized up to 3,600 psi. This fuel is kept as a gas form in the vehicle. LNG involves compressing and cooling natural gas to around -260°F, which converts the gas to a liquid and cuts its volume to 1/600th of its original state.
CNG advantages include:
- Cost, because CNG is significantly less expensive than gasoline, diesel, and LNG.
- Availability, because CNG is more accessible than LNG. Dominion Energy has 24 public stations mostly along the freeway corridors in Utah and southwest Wyoming.
- CNG is very appealing for fleets that return to base each day. Trucks are connected to CNG refueling lines at the end of shift and are full for the next shift, improving fleet and employee efficiencies.
CNG disadvantages include:
- Because CNG remains in a gaseous state, it requires more frequent refueling.
- More or larger tanks are needed to increase range.
- More tank storage can create a challenge if space is limited on a given vehicle.
- Refueling stations are not as available as liquid petroleum locations.
LNG advantages include:
- Increased fuel volume extends range between refueling.
- LNG is a great fit for marine use. It is quickly becoming popular in the cruise ship and freight liner markets. The volume of fuel being used offsets the cost to liquefy and greatly improves the emissions created by these otherwise large diesel engine polluters.
- Safety, because LNG is not stored under high pressure and is not explosive. Although a large amount of energy is stored in LNG, it cannot be released rapidly enough to cause an explosion.
- Higher fuel cost to liquefy the gas.
- Fewer LNG stations than CNG stations.
- Access to refueling is limited.
- Trained attendants must do the refueling.
“Typically, LNG fuel can be packaged in a smaller space due to the liquification of the fuel (i.e., same energy in a condensed form) for the same effective range when compared to CNG,” Donnell said. “This is an advantage for packaging for applications where space is limited. The benefit for CNG is the gas remains in one state throughout the process so no additional energy is required to change phases. Cummins Westport natural gas engines perform the same regardless of how the natural gas is stored, either as a gas or cryogenically-cooled liquid. The greatest majority of our engines purchased today operate on CNG in a wide range of applications, as this is the state in which natural gas is transported around the country through major transmission lines.”
“From an operating perspective, the engine only sees methane molecules,” Swenson added. “Both CNG and LNG are identical as long as they meet the fuel standard requirement. The issue is how much fuel can be stored onboard and the weight of that system. Historically, LNG was viewed as necessary to achieve long range/decrease the frequency of refueling. However, as CNG tanks have become lighter and many areas are allowing vehicles’ extra weight, upwards of 1,000 miles are achievable with CNG tanks.”
Improved truck technology
“In June of 2017, Cummins Westport introduced its “nearly no NOX” Classes 6, 7, and 8 large truck engines,” said Brown. “This new technology for large truck engines has basically created a “net zero carbon footprint” for an internal combustion engine. According to Cummins Westport, ‘the new natural gas engines deliver higher torque than higher horsepower diesel engines over a wider RPM range.’ This engine produces zero particulate matter.” Specifically, the nearly no NOX engine operates at 0.02g/bhp.
“The new technology CNG fuel engines from Cummins Westport produce emissions from a truck comparable to an electric vehicle,” said Rob Bacyinski, program manager, NGV Business Development, DTE Energy Gas Services. “The improvements in the technology for adding CNG fuel storage to the trucks and reduction in costs have provided OTR trucks with more than adequate range. Examples in Michigan include a company called UBCR, which deploys a fleet of 16 OTR CNG trucks throughout the state picking up recyclable beverage containers from retailers. Another in Michigan is FCA Transport (Chrysler Transport), which deploys a fleet of 180 OTR CNG trucks based in Detroit that moves vehicle products throughout the Midwest. For example, an FCA CNG truck from Detroit will pick up an FCA transmission from Indiana and deliver it to a vehicle production facility in Canada.”
“Cummins Westport (CWI) natural gas engines operate at 0.02g/bhp NOX emissions, which is 90% below current EPA standards of 0.2g/bhp, and when operated with RNG, operate with a net negative (less than zero) GHG result,” said Thomas Hodek, director of sales and marketing at Cummins Westport. “This is technology available today, is certified by the EPA, and certified to the lowest of CARB’s options of low NOX standards.”
“Advances in CNG tank technology have brought tank prices down, making the shift to CNG more cost effective,” added Brown. “In addition, advances in CNG conversion kits have enhanced the conversion of light duty, and half- and three-quarter-ton trucks. This technology allows gasoline trucks to now become bi-fuel. Technology has enhanced the performance of these bi-fuel vehicles to run on either natural gas or gasoline by flipping a switch.
Enjoying environmental and cost benefits
Donnell said that more stable and typically lower-priced fuel costs and maintenance-free exhaust treatment systems operated in a longer period of ownership more than offsets by a wide margin any cost difference RNG powered vehicles over the incumbent technology. Swenson added that natural gas engines already have emissions at the NOX levels being contemplated by CARB and EPA in the future, with a simple 3-way catalyst muffler system. “When we look at well-to-wheels, these engines are comparable to, or better than, the emissions associated with charging and electric vehicles. Using certain RNG streams even results in a net negative carbon intensity impact,” he said.
Brown shared the following environmental and cost information:
- Replacing one traditional diesel-burning, heavy-duty truck with one new CNG heavy-duty truck is the emissions equivalent of removing 119 traditional combustion engine cars from our roads.
- New natural gas engines are 90% cleaner than the cleanest diesel engines available.
- When a new natural gas truck runs on RNG, it has a net negative carbon footprint.
- Natural gas trucks cost approximately $20,000 more than a diesel model. Federal and state grants are available to make up for the incremental costs. Without the help of grants, differential payback from fuel costs depends on miles driven; general payback is around two years based on a $2 difference in fuel price.
“Since the No. 1 source of urban emissions is transportation emissions, and three out of every four trucks on the road today is not EPA certified, cleaner air starts with cleaner trucks and buses, especially heavy-duty trucks and buses,” Gage said. “And purchasing new natural gas vehicles is the most cost-effective NOX emissions reduction of any alternative. In addition, RNG, or biomethane, is furthering the natural gas transportation story.”
– This article appeared in the Gas Technology supplement.