Liquefied natural gas (LNG): storage, transport and applications

What changes with LNG?

Liquefaction reduces natural gas volume by approximately 600 times. This high volumetric concentration makes LNG convenient for transporting large fuel stocks without a trunk pipeline.

Compactness requires maintaining the product in a cryogenic state. The tank is therefore designed as an insulated system that limits environmental heat ingress, controls pressure and safely releases excess gas when necessary.

Methane is lighter than air, but ventilation and gas detection remain essential. A leak in an enclosed space can create a hazardous concentration, so cryogenic operation focuses on leak prevention, pressure control and compliance with process procedures.

LNG and CNG: different ways to store the same gas

CNG stores natural gas compressed at high pressure, while LNG uses cooling to convert it to liquid. The 2021 materials quote CNG pressure of around 247 atmospheres and note heavy cylinders and lower gas capacity for the same geometric tank volume.

For LNG, the main engineering challenge shifts from high pressure to insulation and heat ingress management. Choosing CNG or LNG therefore depends on energy storage needs, route length, refuelling infrastructure, space and operating conditions.

In practice, CNG suits many urban and medium-duty applications, while LNG is particularly attractive for large fuel reserves, long ranges or gas delivery to users without pipeline connections.

The LNG chain: production, storage, delivery and regasification

A typical chain starts with natural gas liquefaction and buffer storage. The product is transferred to a transport cryogenic tank, delivered to the customer, and either used as liquid motor fuel or regasified back into gas.

This arrangement supplies natural gas to sites far from trunk networks. Tank containers deliver LNG to remote areas, connecting production with local users.

An industrial project must calculate the entire chain: LNG source capacity, buffer storage, transport distance, daily consumption, required reserve, vehicle downtime and regasification capacity.

Cryogenic LNG tank container

The example is a multimodal ISO container with a capacity of 43.5 m³, gross mass up to 36 tonnes and maximum working pressure of 10 bar. It uses a full-frame 40-foot arrangement and multilayer vacuum insulation.

The quoted vent-free holding time is up to 100 days at 81% fill and up to 30 days at 95% fill. This illustrates a key feature of cryogenic logistics: holding time depends not only on insulation quality, but also on filling level, initial product condition and permitted working pressure.

Multimodal containers are subject to ISO 1496, ADR, RID, the IMDG Code and EN 13530 requirements. The specific requirements depend on gas type, route and the applicable editions of the regulations.

LNG as a heavy transport fuel

LNG allows heavy vehicles to carry a large fuel reserve in less space than an equivalent CNG supply. During engine operation, liquid gas evaporates in a heat exchanger, and a regulator maintains the required gas pressure before it reaches the engine.

The example system includes a 500-litre tank, working pressure up to 16 bar and ambient temperature range of −40 to +45 °C. A one- or two-tank configuration has an indicative refuelling range of 800–1,200 km.

These figures apply to a particular development and are not universal values. Design must consider engine consumption, useful tank capacity, allowable mass, chassis installation, product holding time and refuelling infrastructure.

Selecting a cryogenic tank

Start with the product and its operating conditions. Define gas composition, temperature, design and working pressures, required capacity, filling conditions and cycle frequency. Then select the inner vessel material, insulation, valves and piping arrangement.

Next consider logistics. A tank container requires the right ISO size, gross mass, compatibility with road, rail and sea infrastructure, handling capability and securing provisions. For a stationary tank, foundations, piping and regasifier capacity take priority.

The third area is operation: safety valves, pressure monitoring, interwall vacuum, access for diagnostics and maintenance schedules. Even a well-designed tank needs insulation and leak-tightness monitoring throughout its service life.

Where LNG is especially useful

Sespel’s materials identify long-haul commercial transport, shipping, railway transport and independent gas supply for sites without trunk pipeline connections as target applications.

For remote users, LNG effectively turns gas infrastructure into a logistics system: instead of building a long pipeline, LNG is produced or purchased, delivered in cryogenic tanks and regasified on site.

Economics depend on more than fuel price. Calculations include the tank fleet, transport distance, equipment utilisation, evaporation losses, transfer infrastructure, maintenance and backup supply.

Average Russian motor fuel prices for 2020 are provided only as a historical example. They are outdated and unsuitable for current economic calculations, but illustrate the relative economics of natural gas fuels at that time.