With sustainability becoming an increasingly important issue to industries the world over, liquefied natural gas (LNG) – a freezing cold, liquefied form of natural gas – is playing an increasingly important role in lowering CO2 emissions for transport industries around the world.

What is LNG

LNG is a clear, colourless and non-toxic liquid which forms when natural gas is cooled to -162ºC (-260ºF). The cooling process shrinks the volume of the gas 600 times, and in its liquefied state, LNG is odorless, colorless, non-toxic, and non-corrosive, making it safe and easy to store and transport.

When used on a ship the gas is stored in its liquid state, then re-gasified for burning to power steam turbines or dual fuel engines.

Why use LNG?

LNG is hugely environmentally friendly when compared to heavy fuel oils. LNG releases absolutely zero sulfur, 99% less particulate emissions, 85% less NOx emissions, and 25% less greenhouse gas emissions. As environmental regulations on the industry get ever tighter, LNG seems the ideal solution for companies seeking to comply with MARPOL regulations, and to meet the IMO’s 0.5% global cap on heavy sulfur content by January 2020. Within the industry, there is a growing consensus that LNG is the best solution moving towards 2050, as there are no alternative solutions that can match it’s emissions profile and scalability

Due to the clean nature of LNG, users will experience less wear and tear on engines, and benefit from lower maintenance costs. Engines that are designed for and use LNG won’t need to install scrubber systems or pay high prices for low sulphur fuel.

There is also a strong economic argument to using LNG, as it offers almost 25% more energy output per tonne than HFO (Heavy Fuel Oils). Due to the environmental benefits offered by the fuel’s use, many sustainability conscious bodies are offering grants and subsidies to convert or build new ships for using this fuel.

Strong commercial incentives exist too, as previously unvisited areas, that don’t allow cruise ships with high emissions to dock, may now be accessible to the cruise lines that adopt LNG as a fuel. For example, with Arctic ice receding enough to open new trade routes, international bodies are discussing how to utilize these routes without causing damage to the vulnerable Arctic environment. As a clean gaseous bunker fuel, LNG poses no environmental threat to these unpolluted waters.

Obstacles to using LNG

LNG use does require some reworking in the engine room to support the conditions required to keep the gas in its liquefied state at a temperature of 260 degrees below zero. The tanks containing the gas also have to be vacuum insulated and double-hulled for safety, resulting in a much larger footprint than traditional diesel tanks. This means that for re-fits, converting to LNG can be a costly and complex endeavor. However, as mentioned above, financial incentives are available for those willing to make the commitment.

LNG also requires specific bunkering and refuelling stations, and these may not yet be widespread enough to facilitate LNG’s use as a total replacement for diesel or HFO. Some LNG powered ships are designed to switch to the diesel used as pilot fuel if they start running low and aren’t near bunkering vessels. However, facilities are increasing, as LNG bunkering has grown to encompass 24 out of the world’s top 25 and all but one of the top ten bunker ports globally. Hopefully, as this trend continues to grow, more and more companies will be able to make the switch to LNG.

LNG Powered Ships

AIDAnova was the world’s first liquefied natural gas (LNG) powered cruise ship, constructed for Carnival Corporation’s German cruise line AIDA Cruises in 2018. AIDAnova is capable of operating both in port and on the open sea using four Caterpillar dual-fuel hybrid engines driven by LNG. A further 7 LNG powered ships are planned to be operational for Carnival by 2020.

P&O cruises also have a number of LNG fuelled ships on the order books for delivery by 2025. The shipping sector is also taking advantage, with many container ships starting to utilise LNG.

According to LNG World Shipping, the global LNG fleet is likely to reach 600 vessels by the end of this year.