10 Questions You Should to Know about LNG Dispensers

-1. How many liters of diesel fuel does one cubic meter of natural gas equal? How to convert between natural gas and diesel?

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The calorific value of one cubic meter of natural gas is equal to 0.86 liters of diesel fuel; one meter of natural gas produces as much power as 0.75-0.8 liters of diesel fuel.

-2. Some LNG filling stations measure in kilograms and some in cubic meters, which is more reasonable?

Measuring in kilograms and measuring in cubic meters are essentially the same, only the measurement unit is different, which is determined according to the local custom. The unit of measurement in different areas should be determined according to the customer's situation, market situation and other comprehensive analysis. The unit of cubic meter can be used to adjust the sales price according to the change of gasification rate, while kilogram is the more common unit of measurement.

The majority of LNG refueling stations use mass flow meters, which result in minimal discrepancies when selling by kilograms. If selling by volume, consideration needs to be given to the pricing based on the vaporization rate indicator to ensure customer interests are protected.

-3. Why is the LNG filling volume sometimes higher and sometimes lower?

Due to the difference in the origin of the gas source, the density, calorific value, gasification rate and temperature of LNG may be slightly different, the filling volume fluctuates slightly, which does not affect the accuracy of the filling metering.

-4. How is the refueling volume of LNG vehicles calculated? How do I know when I need to refuel?

(1) LNG is measured in the same way as gasoline and diesel oil, one is measured by volume, and the unit of measurement is cubic meter (the unit of measurement for gasoline and diesel oil is liter), and the other is measured by mass, and the unit of measurement is kilogram (the unit of measurement for gasoline and diesel oil is ton). Depending on the measurement habits of different regions, either cubic meters or kilograms can be chosen as the unit of measurement.

Regardless of the unit of measurement, the amount of gas refilled is the same, and the dispenser automatically measures it. The conversion relation is that 1 kilogram of LNG is equivalent to approximately 1.4 cubic meters of natural gas.

(2) The driver's cab of the LNG vehicle is equipped with an LNG liquid level display, which is the same as the fuel level display of a diesel vehicle. The liquid level display includes liquid level icon, liquid level scale, liquid level pointer and liquid level value (L). When the key switch is turned on, the display will be fully illuminated for 3 seconds and then start to display the values of various parameters of the gas cylinder, including the liquid level value and the gas cylinder pressure value.

Select the refueling time, when the liquid volume scale line is lower than the liquid volume warning line (the data is determined by the automobile manufacturer, the liquid volume warning line is generally 12.5% of the effective volume of the cylinder), the status light flashes to remind the customer to refill in time.

-5. How long does it take to refuel an LNG vehicle?

The time required to fill the same volume of LNG and diesel fuel is comparable. The maximum filling capacity of LNG dispenser is 150 to 200 L/min, and the normal filling time is 5 to 10 minutes.

-6.What is the driving range of the LNG heavy-duty truck?

The range of an LNG vehicle is determined by the volume of LNG cylinders and the 100km gas consumption of the vehicle, and can reach 400 to 1,000 kilometers, which is comparable to that of a diesel vehicle. For example, an LNG heavy truck equipped with two 450-liter cylinders can store about 500 cubic meters of natural gas and consume 50 cubic meters of gas per 100 kilometers, which gives it a range of more than 900 kilometers.

-7. What are the advantages of LNG vehicles over diesel vehicles?

(1) Longer mileage: LNG heavy trucks can travel more than 400Km on 450L of fuel, and the refueling time is short.

(2) Better economy: the vehicle saves fuel costs, simple equipment, low maintenance costs, and the vehicle overload effect is more prominent.

(3) High security: LNG's ignition point of 650 ℃, higher than gasoline, diesel; LNG's explosion limit of 5% -15%, the explosion limit is narrower than gasoline, diesel, and gasification density is very low, a slight leakage will be immediately volatile and diffuse, greatly reducing the risk of explosion.

(4) Clean and environmentally friendly: LNG components are pure, less CO emissions.

-8. Can natural gas vehicles use diesel fuel?

Currently, heavy-duty natural gas trucks can only use a single fuel, either compressed natural gas (CNG) or liquefied natural gas (LNG), and cannot use diesel.

-9. What is the gas consumption per 100 kilometers in actual operation of LNG vehicles and how does it compare to diesel?

In actual operation, the fuel consumption of LNG vehicles per 100 kilometers is approximately 50 cubic meters for heavy-duty LNG trucks with the same power as diesel trucks that consume 40 liters per 100 kilometers. This difference may vary depending on the quality of the gas source.

-10.Why is it necessary to periodically vent LNG tanks, and is it dangerous?

If a liquefied natural gas (LNG) vehicle is not used for a long time, the liquid inside the gas cylinder continuously vaporizes, causing the pressure inside the cylinder to increase. When the pressure exceeds a certain value, the secondary safety valve of the cylinder automatically opens to release pressure, ensuring the safety of the cylinder. In case the secondary safety valve fails or malfunctions, the main safety valve activates to protect the cylinder's safety.

In the event of accidents such as damage to the cylinder shell by external forces, vacuum failure, or a sudden increase in system pressure, the main and secondary safety valves open sequentially to release pressure, ensuring the safety of the vehicle. When venting the gas cylinder, since the main component is methane, which is lighter than air and easily dissipates, it does not easily accumulate and pose a danger.

-11. During the refueling process for natural gas vehicles, filling stations require that no one be seated in the vehicle because it is unsafe?

Comparative ignition points: Diesel has an ignition point of 220°C, while gasoline has an ignition point of 427°C. However, gasoline has strong volatility, and gasoline vapor has a lower ignition point than diesel. The ignition point of liquefied petroleum gas (LPG) is 490°C, and the ignition point of natural gas is 650°C. The density of liquefied petroleum gas (LPG) compared to air is 1.5 to 2, and in the event of a leak, it tends to settle downward, posing a safety hazard for potential explosions.

The density of natural gas (NG) compared to air is 0.58 to 0.79, and in the event of a leak, it quickly dissipates into the air, posing minimal safety hazards. The explosion limits for liquefied petroleum gas (LPG) are between 1.7% and 9.7%, while for natural gas (NG), they range from 5% to 15%, making explosions less likely. LNG has a lower filling pressure compared to CNG, approximately 1/40th of the filling pressure of CNG, making it less prone to leakage. The filling pressure for LNG is only 0.5 MPa, whereas for CNG, it is 20 MPa.

From the above, we can see that the safety indexes of LNG are higher than those of common fuels, so the safety of using LNG as fuel is higher than that of other fuels. However, from the point of view of better guaranteeing the safety of passengers, ensuring the control of open fire hazards in the filling station, and effectively controlling the safety risks, it is required that no one can sit in the vehicle when filling up at the filling station.

-12. Are LNG cylinders safe?

Before LNG storage tanks are shipped from the factory, they undergo special inspections. In addition to routine inspections, the tanks are also subjected to tests such as fire, explosion, drop, and gunshot tests. Only after passing these tests can they be used in the factory. LNG tanks for vehicles are designed as low-temperature, insulated pressure vessels with a double-layer (vacuum) structure.

The inner vessel is used to store the low-temperature liquid liquefied natural gas (LNG), with multiple layers of insulation material wrapped around its outer wall, providing excellent thermal insulation performance. Meanwhile, the interlayer (the space between the two layers of the container) is evacuated to a high vacuum, collectively forming an effective insulation system. The design of the outer shell and support system can withstand the external forces generated by the vehicle during operation.

The inner vessel is equipped with dual-level safety valves to provide protection in case of overpressure. In the event of overpressure, the primary safety valve (opening pressure approximately 1.6 MPa) is the first to open. Its function is to release pressure caused by abnormal heat loss due to insulation layer and support system failure, vacuum breakdown, and accelerated heat loss under conditions of fire.

The secondary safety valve (with an opening pressure typically above 2.4 MPa) is set at a higher pressure threshold compared to the primary safety valve. It activates when the primary safety valve fails or becomes blocked.

The protection of the shell under internal overpressure conditions is achieved through a circular vacuum plug. In case of a leak in the inner container (resulting in excessive pressure in the annular space), the vacuum plug will open to release pressure when it reaches 0.1 to 0.2 MPa. If the vacuum plug itself leaks, it can lead to vacuum failure, which can be identified by the appearance of large water droplets or frost on the outer shell. However, frosting or condensation at the end of the connected pipeline to the cylinder is normal. All pipelines and valve components are located at one end of the cylinder and are protected by protective rings or covers.

-13. Will LNG be prone to explode when the vehicle is involved in an accident or collision?

LNG is stored in insulated containers with pressures ranging from 0.05 to 0.5 MPa. Compared to CNG, LNG has lower storage pressure and lower density after vaporization (lighter than air), making it prone to rapid evaporation and dispersion in case of leakage, thus reducing the likelihood of combustion. The ignition point of LNG is 645°C, with an explosion limit of 5% to 15%. Liquid LNG is not easily ignited, making it safer than gasoline or diesel.

With emissions regulations getting ever stricter, many ship owners are turning to alternative fuels to power their vessels. Liquified natural gas (LNG) is proving a popular choice – and for good reason. Want to know more about LNG as fuel? Get an expert overview in 17 important questions.

Your choice of fuel affects both your profitability and your vessel’s environmental compliance. Liquefied natural gas (LNG) is a safe and cost-effective fuel that reduces greenhouse gas emissions and other harmful pollutants. LNG is playing a key role as a transition fuel and is widely seen as the first step towards decarbonising the maritime industry.

If you are looking for more details, kindly visit SERLNG.

Switching to LNG as fuel for ship propulsion requires investment but can save you fuel costs, increase your profitability and reduce compliance risks. The expert answers to these 17 questions will tell you what you need to know about LNG as an alternative fuel for shipping.

1. What is LNG?

LNG is natural gas that has been cooled to -162°C (-260°F), turning it into a clear, odourless liquid that is easy to ship and store. LNG is typically 85–95% methane, which contains less carbon than other forms of fossil fuels. It is a compact, efficient form of energy that is ideal for ship propulsion.

2. What is LNG used for?

LNG is primarily used as a clean-burning energy source. It is used for electricity generation, heating, cooking, and as a transportation fuel. LNG is also used as a raw material for products like fertilisers and plastics.

In the shipping industry, LNG as fuel is used for ship propulsion, auxiliary power generation and other onboard energy needs. LNG as an alternative fuel for shipping has gained wide popularity due to its clean-burning properties and potential to help meet stricter emissions regulations.

Handpicked related content: Want to know more about a whole range of alternative fuels? Get the lowdown on future fuels in shipping – and discover which one might be right for your vessel.

3. What are the sources of LNG as fuel for ships? What is bioLNG?

LNG as fuel for ships is produced from natural gas extracted from underground reserves, including both onshore and offshore gas fields.

BioLNG is LNG produced from biogas, which is generated from organic waste like food scraps, agricultural waste, manure and sewage sludge. BioLNG is considered a renewable fuel and can further reduce the carbon footprint of ships using LNG fuel systems.

4. Is LNG just methane?

LNG is primarily methane (typically 85–95%), but it also contains small amounts of ethane, propane and other hydrocarbons. LNG can also contain trace amounts of nitrogen and carbon dioxide. The exact composition of LNG may vary depending on the source of the natural gas and the liquefaction process used.

5. LNG fuel vs. fuel oil: is LNG better than diesel?

Compared to diesel fuel oil, LNG offers several advantages. LNG produces significantly lower emissions when burned, including:

• 20–30% less CO2 
• 15-25% less total GHG
• 90% less NOx 
• 99% less SOx 
• Almost no particulate matter (PM) 
  

LNG engines are also quieter. 

However, LNG has a lower energy density than diesel, so using LNG as an alternative fuel for shipping will require more fuel and therefore larger fuel tanks to achieve the same range.

6. What are the advantages and disadvantages of LNG fuel?

The key advantages of LNG as fuel include reduced emissions and cost competitiveness. There is also an established and continuously growing global network of LNG bunkering facilities.

The disadvantages of using LNG as fuel for ships include the need for specialised equipment and training and the potential for methane slip.

Methane slip is when unburned methane, a potent greenhouse gas, escapes into the atmosphere. Modern dual-fuel engines will minimise this issue. Depending on engine type and load, you can reduce methane slip by up to 65% by upgrading your ship’s existing engines. Over the last 30 years, Wärtsilä has reduced the methane slip from its engines by around 90%.

Handpicked related content: Are you looking for ways to be smarter about methane slip? Discover the dramatic improvements you can make – today.

7. Is LNG environmentally friendly?

LNG is cleaner burning than traditional marine fuels, but it is still a fossil fuel. BioLNG, which is LNG produced from organic waste or biomass, can be considered a more sustainable alternative to fossil-based LNG as it has a lower carbon footprint. However, the production and combustion of bioLNG still emit some greenhouse gases. LNG can be seen as a bridging fuel in the transition to alternative fuels like methanol and ammonia, which aren’t yet widely available at scale.

8. Is LNG a future fuel?

LNG both is and isn’t a future fuel. It enables lower greenhouse gas emissions and reduces other harmful air pollutants compared to fuel oil, but it is still a fossil fuel. Sustainable future fuels are crucial for maritime decarbonisation, but the current cost, limited availability and insufficient infrastructure are challenging for operators. This gives LNG an important role to play in the shipping industry’s transition to a zero-carbon future.

As more ports develop LNG bunkering infrastructure and more ships are built with LNG fuel systems, the use of LNG as an alternative fuel for shipping is expected to increase. LNG is considered a stepping stone on the path to decarbonisation as the industry moves closer to using true future fuels such as methanol and ammonia.

Handpicked related content: What actions do policymakers, industry and individual ship operators need to take to achieve sustainable shipping by ? This report reveals the three key elements of success. 

9. What are the problems of LNG?

There are two main problems with LNG as fuel. Firstly, specialised equipment and training are needed to handle LNG safely. Secondly, LNG is predominantly methane and when burned as fuel unburned methane can escape into the atmosphere. This is known as methane slip and can offset LNG’s environmental benefits because methane is a potent greenhouse gas.

Modern dual-fuel engines can minimise methane slip – in fact, Wärtsilä has reduced methane slip from ship engines by around 90% over the last three decades through engine upgrades and ongoing research and development. 

Handpicked related content: Looking for ways to reduce methane slip? This 60 min webinar shares five winning tactics – and one bonus tactic – with little or no additional investment needed.

Short on time? This five-minute article will give you simple solutions to reduce your methane slip today.

There is also a third problem in some areas where the limited availability of LNG bunkering facilities can be an additional barrier to adoption. Despite these challenges, LNG offers a great opportunity for vessels to reduce emissions and is widely seen as a good first step towards decarbonisation.

10. LNG is often described as a transition fuel. What does this mean?

LNG is often described as a transition fuel because it provides a good first step towards other alternative fuels. Sustainable fuels will be crucial to maritime decarbonisation, but the current cost, limited availability and insufficient infrastructure can make them a challenging choice for operators. 

Converting to LNG is a concrete step towards decarbonisation that vessel owners can take today, helping them to reduce emissions and comply with increasingly strict regulations. Conversion also opens up the possibility to use bioLNG and, eventually, synthetic methane.

11. What are the CO2 emissions from LNG?

LNG produces about 20–30% less CO2 when burned compared to traditional marine fuels like heavy fuel oil (HFO). The exact reduction in CO2 emissions depends on things like engine type, operating conditions and the specific composition of the LNG fuel.

Burning LNG releases about 2.75 kg of CO2 per kg of fuel, while HFO emits around 3.15 kg. While there have been some concerns about methane slip, the latest LNG engine technologies and best practices in LNG handling and storage can help minimise this. Additionally, using bioLNG, which is produced from organic waste, can further reduce the carbon footprint of ships that use LNG as fuel.

While LNG is not a zero-carbon fuel, it does offer a significant reduction in CO2 emissions compared to traditional marine fuels. This gives LNG an important role to play in the shipping industry's decarbonisation efforts until fully renewable alternative fuels are more widely available.

12. What are the lifecycle emissions from LNG?

The lifecycle emissions of LNG depend on factors like methane slip during production and transport, energy sources used for liquefaction and engine efficiency.

LNG produces 20–30% less CO2 when burned compared to heavy fuel oil, but methane slip can negatively offset this benefit. Engine manufacturers like Wärtsilä have been working hard to reduce methane slip. Since , the methane slip from Wärtsilä dual-fuel engines has been reduced by around 90%, taking it from 16 grams per kilowatt hour (kWh) to less than two grams today. Wärtsilä is working on reducing methane slip even further, to less than 1 gram per kWh. When running an engine at optimal load, methane slip can now be minimal.

While Wärtsilä is focusing on reducing tank-to-wake emissions through engine development, producers are working to minimise well-to-tank emissions. They are doing this by investing in carbon capture, using renewable energy to decarbonise energy-intensive processes like liquefaction, and closely monitoring pipelines for emissions.

The shipping industry contributes just 2% of global CO2 emissions but 12% of SOx emissions and 13% of NOx emissions. Switching to LNG as an alternative fuel for shipping reduces emissions across the board, cutting NOx emissions by 85–90%, reducing particulate emissions and completely eliminating SOx emissions.

According to a study by the International Council on Clean Transportation (ICCT), the lifecycle greenhouse gas emissions of LNG can be up to 15% lower than those of heavy fuel oil when considering a 100-year timeframe. Using bioLNG, which is produced from organic waste, can significantly reduce lifecycle emissions, as the CO2 released during combustion is offset by the CO2 absorbed by the organic matter when it is growing.

13. What is the outlook for LNG availability?

The global LNG market is expected to grow significantly in the coming years, driven by increasing demand for cleaner energy sources. According to a report by Shell, the global LNG trade is projected to rise by 21% by compared to levels. The expansion of LNG bunkering infrastructure, with 235 ports offering LNG refuelling by , is making LNG more accessible for the shipping industry. 

14. Do LNG tankers use LNG as fuel?

Many modern LNG tankers use LNG as fuel for ship propulsion and auxiliary power generation. These vessels are often referred to as LNG-fuelled LNG carriers. As newer LNG tankers enter the market and older vessels are phased out, the proportion of LNG tankers using LNG as fuel is expected to increase. This is for three main reasons:

• Environmental benefits: By burning LNG instead of traditional marine fuels, LNG tankers can significantly reduce their SOx, NOx and PM emissions. This helps shipowners comply with increasingly stringent environmental regulations, such as the International Maritime Organization's (IMO) global sulphur cap.
  
• Boil-off gas management: LNG tankers are designed to carry liquefied natural gas at cryogenic temperatures. Despite advanced insulation, some LNG will inevitably evaporate during transport, creating boil-off gas. By using this boil-off gas as fuel, LNG tankers prevent it from being released it into the atmosphere.
• Fuel efficiency: The modern dual-fuel engines used on LNG tankers can operate efficiently on both LNG and traditional marine fuels like HFO, providing flexibility in fuel choice and optimising fuel consumption.

15. How many ships use LNG as fuel?

In there were more than 2,400 vessels equipped to operate on LNG globally, with another 1,000 LNG-fuelled vessels on order. These include over 20 cruise ships – many of which are using Wärtsilä LNG solutions – as well as tankers, containerships and RoRo ferries.

Handpicked related content: Discover the LNG-powered Francisco – the world’s fastest high-speed ferry.

16. Why is LNG an attractive prospect as an alternative marine fuel?

LNG is an attractive alternative marine fuel because it has a lower environmental impact than HFO. It produces significantly less SOx, NOx and particulate matter emissions, helping ships meet stricter regulations. Using LNG as fuel can also reduce CO2 emissions by 20–30% compared to heavy fuel oil.

Additionally, LNG is cost-competitive and increasingly available worldwide, with a growing number of bunkering ports. As the shipping industry seeks to decarbonise, LNG is seen as a viable transitional fuel until alternative fuels like green methanol and carbon-free green ammonia become widely available.

17. Is LNG the future of shipping?

LNG is already playing a significant role in the shipping industry’s transition to cleaner fuels. Its lower emissions and increasing availability make an LNG fuel system an attractive option for many shipowners.

As the industry works towards the IMO's goal of reducing greenhouse gas emissions by at least 50% by , LNG is seen as a transition fuel, paving the way for the adoption of alternative fuels like green methanol and carbon-free green ammonia. This makes investing in flexible dual-fuel engine technology the safest path forward, using LNG as a first step towards a carbon-free future.

For more information, please visit LNG Dispensers.