LPG is seen by shipowners as one of the least expensive fuels for meeting new low-carbon emission rules, but spotty safety rules, a lack of bunkering infrastructure or four-stroke engines able to use it is holding back demand.
LPG has been price-competitive with LNG and at a significant discount to B30 biodiesel, bio-methanol and blue ammonia and green ammonia this year, according toArgus. (see chart).
Taking into account the cost of CO2 traded on the EU emissions trading system (ETS), northwest Europe LPG was pegged at $577/t from 1-28 October compared with LNG at $614/t average (see chart). The EU's ETS for marine shipping started this year and requires ship operators pay for 40pc of their greenhouse gas (GHG) emissions generated on voyages in the EU. Next year, ship operators will have to pay for 70pc of their CO2 emissions.
LPG is one of the fuels that can help ship operators comply with the FuelEU for the next ten years. Starting on 1 January 2025, the EU's FuelEU regulation will require a 2pc cut in the lifecycle greenhouse intensity for bunker fuels burned in EU territorial waters compared with 2020 base year levels. The reduction jumps to 6pc from 2030 and gradually reaches 80pc by 2050.
LPG's lifecycle GHG emissions footprint varies depending on its production pathway. It is pegged at about 81.24 grams of CO2-equivalent per megajoule (gCO2e/MJ), according to technical support documentation from the California Air Resources Board. At this carbon intensity level, LPG is compliant with FuelEU's GHG limit set at 85.69 gCO2e/MJ through year 2034, similar to LNG.
There are 151 operational ships with LPG-burning engines, with another 109 vessels on order by 2028, according to vessel classification society DNV. LPG bunker demand more than doubled to 242,292t in 2023 compared with 101,447t in 2022, according to the latest International Maritime Organization (IMO) data collected from vessels of 5,000 gross tonnes and over.
But LPG bunker demand was dwarfed by comparison with LNG bunker demand, which was at 12.9mn t in 2023, up from 11mn t in 2022, according to the IMO. There were over 700 LNG burning vessels operational this year, with the number growing to 1,162 by 2028, according to DNV data. LPG accounted for 0.1pc and LNG for 6.1pc of global marine fuel demand from vessels with 5,000 gross tonnes and over in 2023.
LNG as a marine fuel has been around longer than LPG. The World Liquid Gas Association, a trade association, began exploring the use of LPG as a marine fuel in 2012. The first LPG-fueled very large gas carrier BW Gemini was retrofitted to burn LPG in 2020. By comparison, LNG for bunkering by LNG carriers have been around since the 1960s. The first LNG-powered container ship was delivered in 2015.
The bulk of the global LPG bunker demand came from LPG carriers. LPG carriers outfitted with LPG-burning engines can burn their own cargo, taking advantage of the ships' existing infrastructure and safety systems and minimizing their operating costs. But LPG demand from other major types of bunker-consuming vessels, such as container ships, dry bulk carriers and oil tankers, is lagging. One reason is only two-stroke LPG-burning marine engines are commercially available, says vessel classification society Lloyd's Register. Typically, large vessels use two-stroke engines for propulsion and four-stroke engines as auxiliaries, meaning auxiliary engines on vessels would need to be decarbonised through an additional fuel, says Lloyd's Register.
LPG has a well-developed global network of import and export terminals. But LPG for bunkering port infrastructure, such as dedicated bunkering storage tanks and LPG bunkering barges, is mostly lacking.
Unlike LNG for bunkering, LPG for bunkering regulatory guidelines are currently patchy. If leaked onto water, LPG rapidly vaporises and then sinks to the surface of the water given it is heavier than ambient air. If it ignites, it can create a "pool fire" that can spread and cannot be extinguished, continuing to burn until all the LPG is consumed, Lloyd's Register says.
