CNG is natural gas compressed to 3,600 psi and stored as a gas; LNG is natural gas cooled to about −260°F and stored as a liquid in an insulated tank. LNG packs roughly 2.4 times more energy into the same tank volume, which made it the long-haul choice for a decade, but it boils off if the truck sits, needs cryogenic handling, and has only 21 public stations in the U.S. against 674 for CNG. Since the 2018 ISX12N and the 2024 X15N engines, most new natural gas tractors are ordered as CNG.
Side by side
| CNG | LNG | |
|---|---|---|
| How it is stored | Gas at 3,000 to 3,600 psi in a steel, aluminum or composite cylinder | Liquid at about −260°F and 50 to 150 psi in a vacuum-insulated stainless tank |
| Energy per tank volume | About 25% of diesel | About 60% of diesel |
| Typical tractor range | 500 to 900 miles with a 100 to 175 DGE package | 600 to 1,000+ miles with twin 100-gallon tanks |
| Fill time (Class 8) | 10 to 15 minutes at a quick-fill station; hours at time-fill | 10 to 15 minutes; gloves and face shield required |
| Sitting idle | No loss | Tank pressure rises as liquid warms; vents after roughly a week or two parked |
| Public U.S. stations | 674 | 21 |
| Price unit | GGE or DGE | DGE |
| Engine | Same spark-ignition engine; the fuel arrives as gas either way | Same engine; LNG is vaporized on board before injection |
Range and weight
The whole argument for LNG is density. Liquefying natural gas shrinks it about 600 times, so an LNG tank the size of a diesel saddle tank holds about 60 percent of a diesel tank's energy. A CNG cylinder of the same volume holds about 25 percent. For a tractor that needs 800 miles between fills, LNG gets there with two tanks; CNG needs a large cylinder package behind the cab and on the rails, adding weight and cost.
What changed is the cylinder package. Type 4 composite cylinders and back-of-cab racks now carry 150 to 175 DGE without a large weight penalty, and regional fleets that fill daily never needed 800 miles anyway. The 15-liter X15N engine's 500 hp removed the last reason to prefer diesel for weight-sensitive long-haul, and it was launched as a CNG engine first.
Stations
An LNG station is a cryogenic tank farm: liquid delivered by tanker, stored cold, pumped through an insulated dispenser. It cannot be built at an ordinary gas station and it is expensive to keep cold at low volume, which is why the public LNG network never grew beyond a few dozen sites concentrated on California and Texas freight lanes. The LNG station page lists every public one. A CNG station only needs a gas line, a compressor and storage, so utilities, truck stops and city fleets have built 674 public ones, mapped on the directory.
Some LNG stations also dispense CNG made on site from the liquid (called LCNG), which is why a few sites appear on both lists.
Cost
Both fuels start from the same wholesale gas. LNG adds the cost of liquefaction and cryogenic trucking; CNG adds compression at the station. In DOE's price reports LNG has generally priced a little above CNG per DGE, and the federal excise tax is set per DGE for LNG (24.3 cents) and per GGE for CNG (18.3 cents), which works out about the same per unit of energy. The bigger cost difference is the vehicle: LNG tanks are more expensive than a CNG cylinder package of the same range, and the fill procedure needs trained drivers with protective equipment.
Which one for which truck
- Refuse, transit, drayage, regional and most new long-haul: CNG. Daily yard fueling or a corridor of quick-fill stations, no boil-off, the larger network.
- Dedicated long lanes with LNG at both ends: LNG still works, especially for fleets that built around it before 2018, and some operators run mixed fleets.
- Anything that sits for a week: CNG. A parked LNG truck vents fuel.
The CNG trucks page covers the engines and tank packages; the corridor pages show where the CNG fills actually are.
FAQ
Is LNG or CNG better for trucks?
For most fleets today, CNG: the same engines run on it, the public station network is roughly thirty times larger, and modern cylinder packages give 500 to 900 miles of range. LNG's advantage is density for very long lanes, at the cost of boil-off when parked, cryogenic handling and a small station network.
Can a CNG truck use an LNG station?
Not unless the station also dispenses CNG. Some LNG stations vaporize and compress the liquid on site to sell CNG (LCNG); those appear in both lists on this site. A pure LNG dispenser cannot fill a CNG cylinder.
Why are there so few LNG stations?
An LNG station is a cryogenic facility that must be supplied by tanker and kept cold, which is expensive at low volume, and the natural gas truck market shifted to CNG after 2018 as engines and cylinder packages improved. The DOE lists about two dozen public LNG stations in the U.S.
Does LNG evaporate in the tank?
Yes. LNG warms slowly even in a vacuum-insulated tank; pressure rises and, after roughly one to two weeks parked, the tank vents gas through a relief valve. A truck that is driven daily uses the fuel before that happens.
What is LCNG?
CNG made at an LNG station by vaporizing and compressing the liquid. It lets an LNG site serve CNG vehicles without a pipeline connection.
Find a station
Every public CNG station, with the badges this guide explains.