CNG vs. LNG – What’s the Difference?

Which Is Best for Your Commercial Fleet?

Your fleet needs fuel to power through daily tasks and keep your business operating smoothly. Many fleet managers turn to diesel or gasoline fuels to fill this role. Though gasoline and diesel are a common choice among commercial fleets, many fleet managers are looking to fuel alternatives for their low cost, availability, and environmental benefits.

Regardless of whether you’ve considered alternative fuel, your fleet is always looking for ways to reduce costs and increase efficiency. Natural gas fuel may provide the edge you need to improve performance across the board. Your fleet can either utilize compressed or liquefied natural gas options. Each fuel type has unique qualities, and the type that works best for you depends on a variety of factors.

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What Is Compressed Natural Gas (CNG)?

Compressed natural gas (CNG) is an alternative fuel made from natural gas. CNG is formed by compressing natural gas to less than 1% of its volume at standard atmospheric pressure. This compressed gas is stored in a vehicle in its gaseous state with a pressure of up to 3,600 pounds per square inch.

Like gasoline-powered vehicles, CNG vehicles use a spark-ignited internal combustion engine. CNG is stored in a fuel tank or cylinder until it is transferred to the engine intake manifold or combustion chamber. There, the pressure is reduced to work with the engine’s fuel injection system, and the CNG is mixed with air. Spark plugs then ignite the CNG and air mixture to power the engine.

CNG vehicles have a similar fuel economy to gasoline vehicles measured on a gasoline gallon equivalent (GGE). One gallon of gasoline is equal to about 5.66 pounds of CNG.

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What Is the Difference Between CNG and LNG?

Aside from the fact that CNG is a gas and LNG is a liquid, these fuels have various characteristics that set them apart. When comparing CNG versus LNG, you may find one fuel type works better for your fleet than the other. Here are some key differences to consider.

Application

The density of CNG and LNG makes them suitable for different vehicle types and applications. As a gas, CNG doesn’t pack as much energy into its volume. However, CNG has a wider range of applications across light, medium, and heavy-duty vehicles.

LNG has an increased energy density, which makes it suitable for longer-range vehicles like Class 7 and 8 trucks. You can use LNG for more medium to heavy-duty applications.

Price

According to data from the U.S. Department of Energy, CNG and LNG have had relatively similar or lower costs as compared to gasoline and diesel since 2000.

Individually, CNG and LNG have slightly different price points:

• CNG prices: Over the past two decades, CNG has been less expensive per GGE than gasoline, diesel, and LNG. Though CNG prices fluctuate like those of other fuels, they have fewer drastic spikes when compared to gasoline and diesel.
• LNG prices: Because LNG has a more involved production and transportation process, its prices are typically higher than CNG prices. However, LNG has maintained consistent prices with gasoline and diesel fuels and has avoided major price spikes.

When you switch to CNG or LNG, you won’t have to worry about increased fuel costs. On the contrary, you’ll likely enjoy decreased or unchanged fuel costs.

Fueling

CNG and LNG have different fueling methods and requirements based on their composition. CNG offers fueling options that are similar to traditional gasoline or diesel fueling.

There are two types of CNG fueling stations available:

• Fast-fill stations: Fast-fill stations receive natural gas from a pipeline, compress it onsite, and move it to storage vessels. These stations allow consumers to fill a car or light-duty vehicle quickly with the help of a special dispenser.
• Time-fill stations: Time-fill stations deliver CNG at a lower pressure than a fast-fill setup and do not use storage vessels. These stations use large compressors to fuel vehicles over a longer period compared to fast-fill stations. A time-fill station is ideal for commercial vehicle fleets to use for overnight fueling.

LNG has some unique fueling requirements because it is super-cooled. Trained personnel must wear protective clothing, face shields, and gloves when handling LNG. In contrast to CNG, LNG has a fuel time similar to diesel.

To accommodate these requirements, there are two types of LNG fueling stations available:

• Containerized stations: Containerized stations utilize storage tanks, dispensing equipment, metering, and containment to create an LNG fueling station for your fleet.
• Permanent stations: A permanent station has the same features as a containerized station with an increased storage capacity. These stations can be customized to fit your fleet’s needs for greater convenience.

The Benefits of Switching Your Fleet to Natural Gas

Considering CNG versus LNG for your commercial fleet is an important, win-win decision. Both natural gas fuels offer a host of benefits for your fleet, business, and the environment. Here are some of the things you can expect when you switch to natural gas.

Steady Fleet Performance

Getting adequate power and performance from your vehicles is non-negotiable. No matter the industry, you need to know that your equipment will deliver day after day. Rest assured that, with natural gas vehicles (NGVs), you won’t sacrifice your fleet’s performance. According to the U.S. Department of Energy, NGVs have similar power, acceleration, and cruising speed capabilities when compared to gasoline and diesel vehicles.

Though CNG and LNG don’t provide as much driving range as most gasoline or diesel vehicles, your natural gas fuel choice can mitigate this discrepancy. If a long range is important for your vehicles, you can choose LNG vehicles and add extra storage tanks to maintain the range you need.

Lower Emissions

One key benefit of switching your fleet to natural gas is lowering your overall emissions. When it comes to tailpipe emissions, NGVs have comparable levels to newer gasoline and diesel vehicles. This is because all new vehicles are equipped with emission control systems that must comply with emissions standards.

Not all gasoline and diesel fleet vehicles are new and emission-friendly. According to NGV America, medium- and heavy-duty vehicles are the number one source of smog. Replacing your vehicles with NGVs can cut down on EPA criteria pollutants, especially nitrogen oxide. Overall, light-duty vehicles running on conventional natural gas can reduce lifecycle greenhouse gas emissions by 15%. And because CNG fuel systems are completely sealed, they produce no evaporative emissions.

If your business or customer base champions environmental causes, switching to natural gas fuel sends a clear message.

Natural Gas Availability & Economy

As a resource, natural gas is abundant and readily available in the U.S., especially when compared to the petroleum used to make gasoline and diesel. With natural gas recovery operations in 33 states, the United States is the number one producer of natural gas in the world. The large supply of natural gas in the U.S. keeps CNG and LNG prices low and stable. While gasoline and diesel prices fluctuate based on the global crude oil market, natural gas remains relatively unaffected.

Natural gas also supports the U.S. economy. When you use domestically produced fuel, you contribute to the American economy and help employ American workers. NGVs further diversify fleet fueling, which can reduce the impact of international fuel supply disruptions. Altogether, natural gas fuels are a secure source of energy with a variety of economic benefits.

Overall Savings

Whether you plan to purchase NGVs or convert your current fleet, you may be concerned about the upfront investment required to switch to natural gas. According to NGV America, your investment will offer returns relatively quickly. With lower fuel and maintenance costs, your NGV may offer a speedy 18- to 24-month payback.

NGVs may experience lower maintenance costs when compared to diesel-fueled vehicles because they do not include:

• A diesel particulate filter
• Diesel particulate filter regeneration or waste disposal
• Selective catalytic reduction
• Diesel emission fluid

In addition to lower maintenance costs, natural gas fuel costs are more affordable. This is due in part to the commodity cost associated with natural gas versus diesel:

• Natural gas: Commodity, distribution, and processing costs come together to determine what you pay at the pump. Natural gas’s commodity costs account for 23% of its price. This small share helps to reduce price fluctuations and keep natural gas costs steady.
• Diesel: Commodity costs account for 60% of diesel’s price. This leaves a much higher margin for price fluctuation based on global supply and demand.

In more ways than one, choosing natural gas for your fleet could provide substantial savings. Whether you’re deploying delivery vans or operating heavy construction equipment, natural gas could transform your fleet into an economical and environmentally-friendly asset.