Australian ports may start receiving liquid petroleum gas-fuelled dry bulkers in the not-too-distant future. Japanese classification society Class NK has given world-first approval-in-principle to Imabari Shipbuilding to build an LPG-powered 180,000 deadweight bulker for the Australian trade.
The vessel has been designed for the long-range Japan/Australia trade by locating the LPG tank at the rear of the ship. Imabari says that will “ensure the cruising distance” between the two countries. Imabari Shipbuilding adds that “nowadays” there LPG supply bases and infrastructure around the globe, which will make the ship’s operation “more flexible”.
The bulker has the special feature that it handles LPG at high pressure and at room temperature. LPG is normally chilled to temperatures considerably below zero. The new design will eliminate the need to deal with naturally-occurring boil-off gas and will make operations easier, Imabari Shipbuilding said.
The shipbuilder added that there will be no need to use low-temperature materials or deep-heat insulation, which will thereby help with cost-competitiveness.
The approval-in-principle takes into account Class NK’s Guidelines for Ships Using Low-Flashpoint Fuels and the IMO’s International Code of Safety for Ships using Gases or other Low-flashpoint Fuels.
Flashy LPG
A “flash point” is the temperature at which a liquid can evaporate at a quantity and rate so that there is a combustible concentration of gas.
LPG is a mixture of the hydrocarbon gases propane and butane. Propane has a flash point of -105 Celsius and butane has a flash point of -60 Celsius. Special safety precautions in respect of fuel leakage aboard ship need to be taken because these gases have low flash points.
The World Liquefied Petroleum Gas Association estimates that, by the end of 2019, there were more than 1,000 facilities around the world that can offer LPG-capable storage facilities, adding that LPG can be supplied as bunkers to vessels using existing terminals and refineries.
Approximately 317 million metric tonnes of LPG were produced around the world in 2019, typically from China, India, Canada, and the US according to the WLPGA and analysts IHS Markit. About 60 per cent of all LPG is produced as a by-product of extracting natural gas and oil from the ground and the remaining 40 per cent is produced as a by-product during crude oil refining.
Burning LPG causes 16 per cent less carbon dioxide emissions, the major greenhouse gas, compared to burning heavy fuel oil. LPG combustion produces virtually no sulphur emissions. Reductions of particulate matter can be expected compared to heavy fuel oil and, potentially, nitrous oxides too.
From LPG to ammonia
Class Society DNV GL points out that LPG-installations can also, potentially, be convertible to ammonia.
“Materials used for LPG tanks and systems will in most cases be suitable for ammonia, and the double barriers and other safety features required for LPG would be just as relevant for ammonia. Some adjustments may be necessary for an LPG-fuelled ship to convert to ammonia but may be limited in scope in many cases,” DNV GL said.
Ammonia is a candidate for being the marine fuel of choice to meet the IMO 2050 emissions goal because it does not produce the climate change gas, carbon dioxide, during combustion. By-products of combusting ammonia are pure water and nitrogen – a gas that already accounts for 78 per cent of Earth’s atmosphere. Ammonia can be manufactured by combining hydrogen and nitrogen. It can potentially be made with renewable energy.
