The emergence of LNG as a cargo and fuel

Tracing the potential and possibilities of liquefied natural gas back to the 1950s. 

Tracing the potential and possibilities of liquefied natural gas back to the 1950s. 

Liquefied natural gas (LNG) is seen today as very much the alternative fuel of the present. With suitable engine design NOx emissions can be very low, SOx are practically non-existent and the gas burns cleanly without smoke or soot. However, its first ‘appearance’ in the maritime world was as a cargo rather than a fuel.

On land consumption 

At the end of the 1950s plans were developed by British Gas for the introduction of natural gas for UK domestic use as a replacement for coal gas. This would require the shipment of the gas in liquefied form, either by putting it under considerable pressure or by cooling it to a very low temperature of around -163°C. The latter became the preferred solution but brought with it considerable problems. 

Without re-liquefaction (a technology now adopted by some LNG tankers) it was essential to insulate the cargo tanks as effectively as possible to prevent the cargo boiling from exposure to the ambient temperature. The most effective insulation materials could not prevent some boil off, at best kept to around 0.25% of the cargo volume per day, and the question then was what to do with this. It could be flared from a mast on the vessel, or perhaps it could be burnt as a fuel. This approach was investigated and found to be perfectly feasible if the LNG was supplied to a ship’s boilers, implying it had to be a turbine-powered vessel.

History LNG 2 Venator engine

Close up of the Sulzer dual-fuel engine installed in the Venator in 1972 (Credit: Author’s collection)

First LNG tankers

The first LNG carrier to enter service was the 5,034 ton deadweight Methane Pioneer which left the Calcasieu River, on the Louisiana Gulf coast, on 25th January 1959 with the world's first ocean cargo of LNG, bound for the UK where the cargo was delivered. The success of the specially modified C1-M-AV1-type standard ship, funded by the UK’s Gas Council, encouraged Conch International Methane Ltd to order the world’s first two purpose-built LNG carriers to be constructed, the Methane Princess and Methane Progress, built by Vickers, and Harland & Wolff respectively.

The 27,400 cubic meter capacity ships were fitted with Conch independent aluminum cargo tanks and entered the Algerian LNG trade in 1964, shipping gas from Arzew to a new terminal on Canvey Island, Essex. They were steam turbine powered with the boil off gas being used as fuel in the boilers and were followed by many similarly powered LNG tankers. 

The import of LNG from Algeria to Canvey ceased in 1981, while Methane Progress was scrapped in 1986 and her sister in 1997.

History LNG 3 modern LNG tanker

Today LNG tankers are designed with a variety of cargo containment systems and are usually dual-fuel powered (Credit: Author’s collection)

Fuel for diesel-engined ships

Meanwhile, during the late 1960s, work had been undertaken in Switzerland by diesel engine builder Sulzer Brothers on the development of a two-stroke engine able to burn LNG as well as heavy fuel oil. It was possible to achieve cylinder outputs of 2,000 horsepower by adding 5% pilot fuel only, and a protype for power plant duty was demonstrated in July 1969. The brake mean effective pressure was 115 lb/sq inch when running on pure methane, and piston speed was 1,220 feet/minute at 120 rpm. It was expected that the appearance of this new class of engine, capable of producing up to 24,000 horsepower per unit, would considerably widen the scope of application for gas burning engines.

So, could an engine of this type using LNG as the fuel be suitable for operation in a ship? In 1972 the question was answered when the 29,000 cubic meter LNG tanker Venator was launched. This vessel, built by Moss Rosenberg in Norway for Peder Smedvig and featuring the builder’s spherical design of cargo tanks, was indeed equipped with a Sulzer engine arranged to burn LNG as part of its fuel system. 

Whilst this installation proved to function perfectly well, the engine output when operating on LNG was just 14,000 horsepower compared with the 20,000 horsepower developed on fuel oil. Thus, to maintain the ship’s designed service speed of 18 knots, an engine 50% bigger than necessary had to be used and this was not economic. In due course Venator was converted to a conventionally powered tanker and perfection of the dual fuel diesel engine for marine use had to wait another 25 years or so. Today, it is well established as the leading alternative to heavy fuel operation, either as dual-fuel or solely on LNG.


John Barnes is a journalist and author and former editor of Marine Engineers Review.