A low-emission transitional fuel for shipping
Liquefied petroleum gas (LPG) is a very light and clean burning fuel extracted from natural gas, and can be stored without almost any degradation. It’s used by billions of people around the world for cooking and heating, although the commercial and industrial sectors are in fact the biggest users.
LPG is mostly propane and butane and gives off more gross energy (it burns hotter) than natural gas. Commercial LPG comes mostly from fossil fuels; it burns more cleanly than many other hydrocarbons, but it does give off carbon dioxide (CO2)
and some carbon monoxide. LPG releases 81 percent of the CO2 per kWh produced by oil and 70 percent that of coal.
Relevance to the shipping industry
Since the IMO 2020 regulation took effect on 1 January 2020, the shipping industry has been working hard to get their fleets up to reduced sulfur oxide (SOx) global standards. While the new regulations are a significant milestone in protecting human health and the environment it also means that the use of cleaner-burning fuels, like LPG are now a “must have” and lines must be diligent in retrofitting older ships and building new ships that conform.
While other fuel alternatives are being developed and tested, the shipping industry is highly interested in LPG. It’s extremely clean burning (can contain close to zero sulfur and meets the requirements for Sulfur Emission Control Areas) as well as lowering CO2 emissions. LPG has a high energy density and is easier to store than LNG or heavy fuels (HFO).
Furthermore, it can be used in current two-stroke engines and because it burns cleaner, engines require less maintenance. LPG is cheaper than marine gasoil (MGO) and is easily obtainable in major ports as well as being used as fuel for LPG tankers.
The Present and Future
MAN Energy Solutions is a market leader and completed the first, successful LPG retrofits for ships engines. The company also developed the world’s first and only dual-fuel engine with liquid gas injection running on LPG (MAN B&W ME-LGIP). Importantly, it can switch between conventional HFO, MGO, and LPG fuels without any loss of performance or efficiency. This flexibility gives the option of using conventional fuels along with LPG to maximize the benefits from market prices and fuel arbitrage.
Shipping companies are already seeing the advantages of MAN LPG technology in their fleets, and the environment around them is benefitting too. In October 2020, the LPG carrier BW Gemini became the first Very Large Gas Carrier (VLGC) to have its low-speed main engine converted to a MAN LPG dual-fuel engine. The client, BW LPG, has now converted other ships in their fleet. They note a 95 percent carbon emission savings by retrofitting vessels to LPG as opposed to new builds. They’ve also seen 10 percent increased fuel efficiency and notable reduction in SOx, CO2, and NOx.
In 2023, the Energy Efficiency Existing Ship Index (EEXI) will come into force. Vessels running on cleaner fuels such as LPG will be in full compliance and offer their owners and operators a distinct commercial advantage.