SummaryShipping represents a significant source of diesel emissions, which affects global climate, air quality and human health. As a solution to this problem, biodiesel could be used as marine fuel, which could help in reducing the negative impact of shipping on environment and achieve lower carbon intensity in the sector. In Southern Europe, some oily wastes, such as wastes from olive oil production and used frying oils could be utilized for production of the second-generation biodiesel. The present research investigates the influence of the secondgeneration biodiesel on the characteristics of gaseous emissions of NOx, SO2, and CO from marine diesel engines. The marine diesel engine that was used, installed aboard a ship, was a reversible low-speed two-stroke engine, without any after-treatment devices installed or engine control technology for reducing pollutant emission. Tests were carried out on three regimes of engine speeds, 150 rpm, 180 rpm and 210 rpm under heavy propeller condition, while the ship was berthed in the harbor. The engine was fueled by diesel fuel and blends containing 7% and 20% v/v of three types of second-generation biodiesel made of olive husk oil, waste frying sunflower oil, and waste frying palm oil. A base-catalyzed transesterification was implemented for biodiesel production. According to the results, there are trends of NOx, SO2, and CO emission reduction when using blended fuels. Biodiesel made of olive husk oil showed better gaseous emission performances than biodiesel made from waste frying oils.

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As a carbon neutral fuel, biodiesel is one option in future IMO scenarios for reducing carbon intensity in shipping sector, and at same time reducing emission of pollutants. Some oily wastes, such as waste from olive oil production, might be used for production of second-generation biodiesel. The current study looks into the effect of biodiesel on the characteristics of gaseous pollutant emissions of NOx and CO from slow-speed two-stroke marine diesel engines that do not have any after-treatment devices or engine control technology installed to reduce gaseous pollutant emissions. While the ship was berthed in the harbor, tests were performed on two separate loads at 210 rpm. The engine was powered by diesel fuel and blends of 7%, 20%, and 25% v/v of biodiesel derived from oily wastes generated during olive oil processing. For biodiesel production in lab conditions, base-catalyzed transesterification was implemented. According to the findings, there are tendencies of reduced gaseous emissions when utilizing blended fuels.

UvodU toku eksploatacije motora njegova snaga se stalno mijenja, zavisno od priklju~enog potro{a~a. U uslovima pogona broda, snaga koju motor predaje propeleru sa nepromjenljivim korakom krila zavisi od broja obrtaja i koraka krila propelera. Otpor koji pru`a propeler nepromjenljivog koraka krila, a koji motor savla|uje, proporcionalan je kvadratu broja obrtaja propelera:Efektivna snaga koju motor predaje propeleru mo`e da se izrazi preko obrtnog momenta koji se sa koljenastog vratila

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