Posted: August 14th, 2022

Assessing the Viability of Liquefied Petroleum Gas as a Clean Marine Fuel Alternative

Assessing the Viability of Liquefied Petroleum Gas as a Clean Marine Fuel Alternative

The shipping industry is facing increasing pressure to reduce its environmental impact and comply with stricter regulations on greenhouse gas emissions, air quality, and marine pollution. One of the options that has gained attention in recent years is the use of liquefied petroleum gas (LPG) as a marine fuel alternative to conventional heavy fuel oil (HFO) or marine diesel oil (MDO). LPG is a mixture of propane and butane that can be stored as a liquid under moderate pressure and temperature. It has several advantages over other fossil fuels, such as lower carbon intensity, lower sulphur content, lower nitrogen oxide (NOx) emissions, and lower particulate matter (PM) emissions. However, it also faces some challenges, such as higher cost, limited availability, safety concerns, and regulatory barriers. This blog post aims to provide an overview of the current state of LPG as a marine fuel and assess its viability and potential in the future.

LPG as a Marine Fuel: Benefits and Drawbacks

LPG is not a new fuel for the shipping industry. It has been used for decades by some vessels that transport LPG as cargo, such as gas carriers and barges. These vessels can use the boil-off gas (BOG) that is generated during the voyage as a fuel for their main engines or auxiliary systems. This reduces the need for external fuel supply and minimizes the cargo losses. However, the use of LPG as a fuel for other types of vessels, such as container ships, bulk carriers, or cruise ships, is still relatively rare and experimental.

One of the main benefits of LPG as a marine fuel is its lower environmental impact compared to HFO or MDO. According to a study by DNV GL, a leading classification society, LPG can reduce the carbon dioxide (CO2) emissions by 17% compared to HFO and by 11% compared to MDO on a well-to-wake basis . This means that LPG takes into account not only the emissions from the combustion of the fuel in the engine, but also the emissions from the production, transportation, and storage of the fuel. LPG can also reduce the sulphur oxide (SOx) emissions by 99%, the NOx emissions by 10%, and the PM emissions by 90% compared to HFO . These reductions can help the shipping industry meet the International Maritime Organization (IMO) regulations on sulphur content in marine fuels, which was lowered from 3.5% to 0.5% in 2020, and on NOx emissions, which will be tightened in 2021 for new vessels .

Another benefit of LPG as a marine fuel is its compatibility with existing engine technologies and infrastructure. LPG can be used in dual-fuel engines that can switch between LPG and another fuel, such as diesel or LNG (liquefied natural gas), depending on the availability and price. Dual-fuel engines can also offer operational flexibility and reliability, as they can adapt to different operating conditions and avoid fuel quality issues. Moreover, LPG can be stored in pressurized tanks that are similar to those used for LNG, but with lower pressure and temperature requirements. This means that LPG can use some of the existing LNG infrastructure, such as terminals, bunkering facilities, and supply chains, with minor modifications.

However, LPG as a marine fuel also has some drawbacks that limit its widespread adoption. One of them is the higher cost of LPG compared to HFO or MDO. According to a report by SEA-LNG, an industry coalition that promotes LNG as a marine fuel, the price of LPG in 2019 was about 1.5 times higher than HFO and about 1.2 times higher than MDO on an energy-equivalent basis . The price difference may vary depending on the regional markets and fluctuations, but it poses a significant barrier for ship owners and operators who are looking for cost-effective solutions. Moreover, the higher cost of LPG may not be offset by its lower environmental impact, as there is currently no global carbon pricing mechanism or incentive scheme for low-carbon fuels in the shipping industry.

Another drawback of LPG as a marine fuel is its limited availability and accessibility in some regions. Although LPG is widely produced and traded around the world, most of it is consumed by residential, commercial, and industrial sectors, rather than by transportation. According to the International Energy Agency (IEA), only about 3% of the global LPG demand in 2019 was from transportation . Furthermore, most of the LPG supply for transportation is concentrated in Asia-Pacific and North America, where LPG is used as an alternative fuel for road vehicles . This means that there may not be enough LPG supply or infrastructure for marine use in other regions, such as Europe, Africa, or Latin America. Therefore, LPG as a marine fuel may face challenges in ensuring its global availability and accessibility for the shipping industry.

A third drawback of LPG as a marine fuel is its safety concerns and regulatory barriers. LPG is a flammable and explosive substance that requires careful handling and storage. It can pose risks of fire, explosion, or leakage if not managed properly. Therefore, LPG as a marine fuel has to comply with strict safety standards and regulations, such as the International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code) . The IGF Code provides mandatory provisions for the design, construction, operation, and maintenance of ships using low-flashpoint fuels, such as LPG, LNG, or methanol. However, the IGF Code is relatively new and not fully harmonized across different regions and jurisdictions. Therefore, LPG as a marine fuel may face some uncertainties and inconsistencies in its regulatory framework and enforcement.

LPG as a Marine Fuel: Outlook and Potential

Despite its drawbacks, LPG as a marine fuel has some potential to grow and expand in the future. One of the factors that could drive its growth is the increasing demand for LPG as a cargo. According to the IEA, the global LPG demand is expected to increase by 16% from 2019 to 2025, reaching 357 million tonnes . The main drivers of this growth are the rising population and income levels in developing countries, especially in Asia-Pacific, where LPG is used for cooking, heating, and petrochemical production . As a result, the global LPG trade is also expected to increase by 23% from 2019 to 2025, reaching 122 million tonnes . This means that there will be more vessels that transport LPG as cargo, such as gas carriers and barges, which could use LPG as a fuel as well.

Another factor that could drive the growth of LPG as a marine fuel is the development of new technologies and innovations that could improve its performance and competitiveness. For example, some engine manufacturers are developing new dual-fuel engines that can run on both LPG and ammonia . Ammonia is another low-carbon fuel that has attracted interest in the shipping industry, as it has zero CO2 emissions when combusted and can be produced from renewable sources . However, ammonia also has some challenges, such as high toxicity, low energy density, and high production cost . Therefore, dual-fuel engines that can use both LPG and ammonia could offer more flexibility and efficiency for ship owners and operators who want to reduce their environmental impact and comply with future regulations.

A third factor that could drive the growth of LPG as a marine fuel is the emergence of new policies and incentives that could support its adoption and deployment. For example, some countries and regions are implementing carbon pricing mechanisms or emission trading schemes that could increase the cost of high-carbon fuels, such as HFO or MDO, and make low-carbon fuels, such as LPG or LNG, more attractive . Moreover, some ports and authorities are offering discounts or subsidies for vessels that use low-carbon fuels or have lower emissions . These policies and incentives could create more demand and market opportunities for LPG as a marine fuel.

Conclusion

LPG is a promising marine fuel alternative that has several advantages over conventional fossil fuels, such as lower carbon intensity, lower sulphur content, lower NOx emissions, lower PM emissions, compatibility with existing engine technologies and infrastructure. However, it also faces some challenges, such as higher cost, limited availability,
safety concerns, and regulatory barriers. Therefore, the viability and potential of LPG as a marine fuel depend on various factors,
such as the development of new technologies and innovations,
the emergence of new policies and incentives,
and the evolution of the global LPG market and trade.
LPG may not be the ultimate solution for the decarbonization of the shipping industry,
but it could play a role in its transition to a more sustainable future.

Bibliography

: DNV GL (2019) Assessment of selected alternative fuels
and technologies dissertation help. Available at: https://www.dnv.com/maritime/alternative-fuels-and-technologies/download-the-report.html (Accessed: 17 January 2024).

: IMO (2020) Sulphur 2020 – cutting sulphur oxide emissions. Available at: http://www.imo.org/en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx (Accessed: 17 January 2024).

: SEA-LNG (2019) LNG: A pathway to net zero. Available at: https://sea-lng.org/wp-content/uploads/2019/12

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