Although there is no internationally agreed definition of biofuels, it is generally referred to as a fuel which can replace traditional fossil fuels, made from biomass as a raw material, and has similar properties to petroleum products. This chapter describes biofuels that can be used in monofuel diesel engines and dual-fuel engines.
It is a low-carbon fuel because its carbon content is relatively low compared to traditional fossil fuels, and it is classified as a carbon-neutral fuel because it uses biomass that has absorbed carbon dioxide from the atmosphere. Because of this carbon neutrality, the use of biofuels is expanding in all industry sectors. While it has the advantage of being easier to store and use than other alternative fuels from the point of view of utilization, it should be noted that storage conditions and periods may differ depending on the type of biofuel.
In the shipping sector, numerous sea trials with biofuel are being conducted, and they are being blended with traditional fossil fuels or completely replacing them in sea trials. Biofuels are receiving attention as a "drop-in" fuel that can be used immediately without the need for significant modification or alteration of internal combustion engines used as main propulsion or electric power generation on ships. If a sufficient supply is available, they can also be used as pilot fuels for dual-fuel engines, ensuring complete carbon neutrality in ships.
In the future, to continuously use biofuels as ship fuel, considerations such as sustainability, price competitiveness, and supply stability need to be taken into account, and compliance with air pollution and GHG regulations must also be considered.
Biofuels can be produced from various materials and manufacturing methods, mainly biomass sources. The representative biofuels are as follows:
Biofuels can be classified according to the raw materials used. First-generation biofuels can use crops for food and animal feed, which can have a negative impact on food production and indirect land-use changes (ILUC) such as assigning pasture or croplands for biofuel production can increase greenhouse gas emissions. Accordingly, it is expected that 2nd generation or higher generation biofuels produced from raw materials with relatively low environmental impact will be used as sustainable fuels.
The price of biofuels can vary depending on the raw materials and manufacturing process, and it is known that biofuels with higher generations have a higher price range compared to traditional fossil fuels. In addition, the availability of biofuels as a fuel may vary depending on the limitations of available raw materials and the demand for biomass in other industrial sectors (power generation industry, land and air transport, etc.).
Biofuels can be produced worldwide, but infrastructure for bunkering biofuels may be limited. However, with the increasing demand and use of biofuels for sustainable fuel from a life cycle perspective due to strengthened GHG regulations, the number of ports capable of bunkering is expected to increase. In addition, for existing "drop-in" biofuels that can replace traditional fossil fuels without requiring significant investment, existing bunkering infrastructure can be used. Rotterdam and Singapore are currently the major biofuel bunkering ports.
To use biofuels by blending or using 100% fuel, nitrogen oxides and sulfur oxides regulations must be met.
It is generally known that the increase in the blend ratio of biofuels also increases nitrogen oxides. However, based on the results of various land and sea trials, it has been confirmed that there is no correlation between the blend ratio of biofuels and the amount of nitrogen oxides emitted. To prevent an increase in nitrogen oxides due to the use of biofuels, sea trials were conducted with flag state approval under the exceptions to Rule 3.2, Chapter 6 of MARPOL Annex, but the amendment to the unified interpretation of Chapter 6 of MARPOL approved at the 78th MEPC meeting(1_78th meeting news). For diesel engines using biofuels with less than 30% blending, the use of the fuel is allowed without onboard nitrogen oxide measurement and verification. However, for biofuels extracted by methods other than petroleum refining or biofuels with a blending ratio of more than 30%, on-board simple measurement or direct measurement must be performed according to the NOx Technical Code 2008.
As there is no sulfur component in biofuels, the increase in the blend ratio of biofuels reduces sulfur oxides, and can also reduce particulate matter due to the oxygen content in the fuel.
Current IMO regulations only regulate CO2 emissions from fuel combustion (from a tank to wake perspective). Relevant regulations do not set a conversion factor (Cf) for biofuel, but considering its chemical composition, it has a CF value that is almost similar to or slightly lower than that of conventional fossil fuels. In the future, it is necessary to pay attention to the LCA guidelines from the life cycle perspective of the IMO, and to pay attention to the setting of emission factors for alternative fuels, including biofuels.
On the other hand, the EU has announced the introduction of regulations from the perspective of the entire life cycle through FuelEU Maritime. Biofuels have different GHG intensity depending on the raw material, but the GHG reduction effect of fuels manufactured with sustainable raw materials is recognized.
Korean Register (KR) recognizes the importance of biofuels as one option for greenhouse gas regulation and has published a technical document (2_Biofuels-Considerations for Ship Application) to provide information on considerations for ship application of biofuels. Prior to the approval of a unified interpretation regarding the blending of biofuels, KR has established a practical cooperation system with a shipping company, engine manufacturers, and biofuel suppliers, and has successfully carried out a sea trial of biofuel blends (MEPC 79-INF.25).
In addition, KR provides technical services on the applicability of biofuels through low and medium speed engine test benches at the Greenship Test and Certification Center(TCC, http://tcc.krs.co.kr) located in Gunsan, Jeollabuk-do.
If you need more information on biofuels, please contact the following information.