Towards Decarbonization of Shipping: Direct Emissions & Life Cycle Trial PDF

**Towards decarbonization of shipping: direct emissions & life cycle impacts from a biofuel trial aboard an ocean-going dry bulk vessel** The study looks at how using a biofuel made from used cooking oil (UCO) affects emissions on a large cargo ship. This biofuel is mixed 50:50 with regular marine...

**Towards decarbonization of shipping: direct emissions & life cycle impacts from a biofuel trial aboard an ocean-going dry bulk vessel** The study looks at how using a biofuel made from used cooking oil (UCO) affects emissions on a large cargo ship. This biofuel is mixed 50:50 with regular marine fuel (MGO) and is tested on the ship's engine. The main goals are to check if biofuel can reduce harmful gases compared to regular fuels and to see how it performs throughout its entire life cycle. **Key Findings:** 1. **Direct Emissions**: When the ship used the biofuel blend instead of regular low-sulfur marine gas oil (LSMGO): - **Carbon dioxide (CO₂)** and **nitrogen oxides (NOx)** were nearly the same as when using regular fuel. - **Sulfur dioxide (SO₂)** emissions dropped by about 50% with the biofuel blend. 2. **Life Cycle Emissions**: Looking at the fuel's entire production and transportation process (life cycle analysis): - Using the biofuel blend could reduce CO₂ emissions by up to 40% compared to regular marine fuel. 3. **Operational Performance**: The ship had no issues running on this biofuel, suggesting it could be a good option for reducing the carbon footprint of cargo ships. **Conclusion**: Although the biofuel blend doesn't drastically lower emissions while being burned, it does reduce overall emissions when you consider the whole life cycle. This suggests biofuels could help the shipping industry move towards decarbonization. The shipping industry currently produces a lot of greenhouse gases (GHGs) and harmful gases like sulfur dioxide (SO₂) and nitrogen oxides (NOx). Shipping makes up about 3% of global GHG emissions every year, with SO₂ and NOx emissions in the millions of tons. With the sector growing and environmental regulations getting stricter, ship owners must find ways to cut down emissions. The **International Maritime Organization (IMO)** set goals to reduce CO₂ emissions by 40% by 2030 and 70% by 2050 (compared to 2008 levels). They also enforced a rule from 2020 that limits sulfur in ship fuel to reduce pollution. Ships are now exploring different ways to reduce emissions, including using biofuels. **Biofuels** are made from organic materials and can help cut emissions: - They can be blended with regular ship fuel and used in existing ships with little or no changes needed. - **Second-generation (2G) biofuels** are the most promising for shipping because they use non-food biomass, like waste products, avoiding the \"food vs. fuel\" issue. While 2G biofuels face some challenges, they are expected to grow in use by 2030 as technology improves. To test if 2G biofuels can help reduce emissions, researchers conducted a trial on a cargo ship. They used a **50:50 mix of a 2G biofuel from used cooking oil** with regular marine fuel. Minor modifications were made to the ship, and special tools were added to measure emissions accurately. The main goals of the trial were to: 1. **Compare emissions** (CO₂, NOx, and SOx) from the biofuel blend with low-sulfur marine gas oil. 2. **Measure life cycle emissions**, including emissions from fuel production and transport, to see if biofuels really help reduce pollution. This trial is important because it's one of the first times emissions from using biofuels in bulk carriers have been directly measured, helping to understand the benefits and challenges of biofuels for the shipping industry. This section provides a detailed overview of the experimental design and methodology for assessing emissions on the *Kira Oldendorff*, a Kamsarmax bulk carrier. Built in 2020, this vessel operates under Liberia's flag and is powered by a MAN B&W 6S60ME-C8.5 slow-speed, two-stroke diesel engine, compliant with IMO Tier II NOx emission standards. The ship has a deadweight tonnage (DWT) of 81,290 tons, an overall length (LOA) of 229 meters, a width of 32.26 meters, and operates at speeds up to 14.7 knots. The main engine provides 9,932 kW at a maximum of 90.2 RPM, with three auxiliary 800 kW YANMAR diesel generators available as backup. The biofuel blend tested consisted of 50% GoodFuels MDF1-100 derived from used cooking oil (UCO) and 50% marine gas oil (MGO), totaling 197.5 tons. Emission measurements were recorded during the biofuel-powered voyage from Singapore to Las Palmas and compared to measurements with low-sulfur marine gas oil (LSMGO) used during the subsequent voyage to Sweden. **Engine Operation Modes and Emission Measurements** The study employed five operational modes to simulate various engine loads, following ISO 8178 standards, with weights assigned to represent operational significance: dead slow (5%), slow (5%), half ahead (25%), full ahead (50%), and full navigation ahead (15%). Emission measurements were taken for each mode, monitoring CO₂ and NOx levels using calibrated Wöhler A 550 INDUSTRIAL and TESTO 350 gas analyzers. **Fuel Analysis and Calculations** Fuel samples of both biofuel and LSMGO were analyzed for chemical and physical properties. Properties included density, viscosity, calorific value, sulfur content, and elemental content. The emission factors (EFs) were calculated from instantaneous measurements, averaged across sampling points, and converted to grams of emissions per kilowatt-hour (g/kWh). The exhaust gas flow rate was estimated using the carbon balance method, aligning with ISO 8178 guidelines, with calculations based on the CO₂ produced during combustion. This robust methodology aimed to provide comprehensive emissions data across varied engine loads and fuel types, contributing to the assessment of biofuel as a sustainable marine fuel alternative. The study investigates the emissions performance of a biofuel blend compared to low-sulfur marine gas oil (LSMGO) across various engine loads, focusing on CO₂, NOₓ, and SO₂ emissions. **CO₂ Emissions** The CO₂ emissions were found to vary slightly by load. At lower loads (modes 1 and 2), the biofuel blend emitted slightly more CO₂ than LSMGO, increasing by 0.4% and 5%, respectively. At higher loads (modes 3, 4, and 5), the biofuel blend showed reductions of 2% to 1% compared to LSMGO. The overall CO₂ reduction with the biofuel blend was about 1.2%, with weighted emissions averaging 571 g/kWh for the biofuel blend versus 578 g/kWh for LSMGO. This minor reduction aligns with the expected lower carbon content of the biofuel blend, though diesel engines typically have similar combustion efficiencies across different fuel types due to high carbon-to-CO₂ conversion rates. **NOₓ Emissions** NOₓ emissions for the biofuel blend were higher than those of LSMGO at lower loads, with increases of 10% and 2% in modes 1 and 2, respectively. However, at higher loads, biofuel blend emissions were lower by 6%, 0.3%, and 14% in modes 3, 4, and 5. This difference is likely due to higher nitrogen content in LSMGO and the higher cetane index of the biofuel, which enhances combustion efficiency and lowers NOₓ production. Overall, NOₓ emissions from the biofuel blend were 3% lower than LSMGO and stayed below Tier II NOₓ limits. **SO₂ Emissions** SO₂ emissions, calculated based on sulfur content, were notably lower for the biofuel blend than LSMGO, with about a 50% reduction overall. This is due to the biofuel's sulfur content being half that of LSMGO, which aligns with international regulations targeting SO₂ reduction in marine fuel emissions. **Comparison with Prior Studies** The study's findings indicate the biofuel blend provides modest reductions in CO₂ and NOₓ emissions compared to similar fuels used in marine applications. Compared to prior studies, the biofuel blend's CO₂ emissions are within 7-34% lower, and NOₓ reductions reach up to 17% when compared to low-sulfur distillate fuels. However, the biofuel blend shows higher emissions than ultra-low-sulfur fuels used in medium-speed engines, primarily due to the combustion characteristics of slower, two-stroke engines and the inherent properties of biofuel. SO₂ emissions remain significantly lower than those found in heavy fuel oil (HFO) emissions studies, highlighting the biofuel's compliance with sulfur restrictions. This study represents the first real-condition onboard emission measurements for a large two-stroke marine diesel engine in a dry bulk carrier using a 50% UCO biodiesel and 50% MGO advanced biofuel blend. Findings are critical for updating emission inventories and evaluating the climate and health impacts of marine emissions. Results indicate that, while the TTW (tank-to-wheel)( **TTW** focuses specifically on the emissions and energy consumption that occur during the operation of the vehicle, from the point where the fuel is stored in the tank to its combustion and usage). emissions from this biofuel blend are like LSMGO, with minor reductions of 1.24% in CO₂ and 3% in NOx, there was a substantial (\~50%) reduction in SO₂ emissions, due to lower sulfur content in the blend. From a WTW(**WTW** refers to the entire lifecycle of a fuel, from the extraction of raw materials to the end-use of the fuel in a vehicle). (well-to-wheel) LCA perspective, using this biofuel blend could lead to a 40% reduction in CO₂ emissions compared to conventional marine fuels. The study underscores that fuels with similar TTW emissions might vary significantly in their overall LCA impacts (life cycle assessment) , highlighting the need for a comprehensive regulatory framework for marine fuel evaluation. No operational issues were observed during the biofuel trial, suggesting that these blends hold promise for short-term decarbonization of dry bulk shipping. However, future assessments should incorporate broader pollutant monitoring (e.g., CO, PM) and additional engine parameters (e.g., intake air, fuel temperature/pressure, exhaust temperature, fuel flow rate) for more thorough comparisons. Validating large-scale industrial data for WTT (well-to-tank) emission assessments and examining biofuels\' long-term operational effects on engines is recommended for a more complete evaluation of biofuels\' potential to reduce the climate impact of maritime transport.