Regulatory agencies monitoring the activities of ships are increasingly adopting eco-friendly measures to combat the environmental damage caused by propulsion fuels. Although liquefied petroleum gas (LPG) is a potential eco-friendly alternative, its viability as a maritime fuel has not been assessed so far. Now, a study conducted by researchers from Korea Maritime and Ocean University shows that using LPG could reduce air pollution, is low-cost, and is applicable regardless of ship size.

The combustion of fuels used for powering ships negatively impacts our environment by releasing harmful pollutants into the atmosphere. As a result, maritime agencies monitoring shipping operations have enforced regulations to mitigate this impact. Considering the current economic feasibility vis-à-vis the regulatory laws and the available technology, liquefied petroleum gas (LPG) is a viable eco-friendly alternative fuel. Given its advantages and market competitiveness, LPG could open doors to zero carbon emission ships. Unfortunately, LPG has found little application so far in the shipping industry and is, therefore, lacking certification.

Against this backdrop, a team of researchers from Korea Maritime and Ocean University, South Korea investigated the feasibility of using LPG as a marine fuel in a new study published in the Journal of Cleaner Production. This paper was made available online on 30th November, 2021, and published in Volume 330 of the journal on 1st January, 2022.

The team, led by Dr. Won-Ju Lee, conducted statistical analysis of a database of 72,098 ships registered in South Korea. "There is a lack of comprehensive assessment of the economic, environmental, and safety aspects of LPG-based fuel systems worldwide. In our study, we identified ships with South Korean registrations that can be converted to LPG fuel use, and determined the reduction in fuel consumption, cost, and air pollutants from using LPG," explains Dr. Lee.

The findings were encouraging. "Unlike current shipping fuels such as heavy fuel oil, LPG does not generate marine pollutants during leaks and is applicable without restrictions on the ship size," says Dr. Lee. According to the study's theoretical estimates, switching to LPG reduced the annual fuel consumption by 7.5–10.4%, fuel cost by 8.8–25.9%, carbon dioxide emissions by 10–14%, nitrogen oxide emissions by 14–16%, and sulfur oxide/particulate matter emissions by 98–99%.

Additionally, the study reviewed the current status of academic research, technological advancement in the area of LPG-fueled engines, development of market competitors, and the safety standards developed by the International Maritime Organization (IMO) for establishing international standards for LPG-fueled ships.

The researchers recommended promoting LPG as an attractive eco-friendly marine fuel by subsidizing its prices and formulating government policies favoring its usage. "The results of this study could provide a reference for the national shipping industry to inform choices on using environment-friendly and low-cost fuel sources," says Prof. Lee. "Additionally, constructing LPG propulsion ships would help in making a more reliable estimate of the total cost of LPG retrofit, conversion, and operation," he concludes.