Knowledge

I this video, Associate Professor Anders Ivarsson (DTU Mechanical Engineering) present the current status of their projects and experimental capabilities in the field of green marine fuels (lignin fuel, ammonia, and dimethyl ether) in their combustion engine laboratory.
The session was developed in collaboration with MARLOG.

Power-to-X plants can generate renewable power and convert it into hydrogen or more advanced fuels for hard-to-abate sectors like the maritime industry. Using the Bornholm Energy Island in Denmark as a study case, this study investigates the off-grid production e-bio-fuel as marine fuels. It proposes a production pathway and an analysis method of the oil with a comparison with e-methanol. Production costs, optimal operations and system sizing are derived using an open-source techno-economic linear programming model. The renewable power source considered is a combination of solar photovoltaic and off-shore wind power. Both AEC and SOEC electrolyzer technologies are assessed for hydrogen production. The bio-fuel is produced by slow pyrolysis of straw pellet followed by an upgrading process: hydrodeoxygenation combined with decarboxylation. Due to its novelty, the techno-economic parameters of the upgraded pyrolyzed oil are derived experimentally. Experimental results highlight that the upgrading reaction conditions of 350 °C for 2h with one step of 1h at 150 °C, under 200 bars could effectively provide a fuel with a sufficient quality to meet maritime fuel specifications. It requires a supply of 0.014 kg H2/kgbiomass. Modeling results shows that a small scale plant constrained by the local availability of and biomass producing 71.5 GWh of fuel per year (13.3 kton of methanol or 7.9 kton of bio-fuel), reaches production costs of 54.2 €2019/GJmethanol and 19.3 €2019/GJbio-fuel. In a large scale facility, ten times larger, the production costs are reduced to 44.7 €2019/GJmethanol and 18.9 €2019/GJbio-fuel (scaling effects for the methanol pathway). Results show that, when sustainable biomass is available in sufficient quantities, upgraded pyrolysis oil is the cheapest option and the less carbon intensive (especially thanks to the biochar co-product). The pyrolysis unit represents the main costs but co-products revenues such as district heat sale and biochar as a credit could decrease the costs by a factor three.

In a premixed dual-fuel (DF) methane-diesel engine, the ignition of the lean premixed methane/air mixture starts with the assistance of a pilot diesel injection. Auto-ignition of pilot fuel is important as it triggers the subsequent combustion processes. A delay in the auto-ignition process may lead to misfiring, incomplete combustion, and thus higher greenhouse emissions due to methane slip. Hence, a better understanding of the auto-ignition process for the pilot fuel can help to improve the overall engine performance, combustion efficiency, and to lower exhaust emission levels. In the present study, large eddy simulation (LES) is used to investigate the auto-ignition process of micro-pilot diesel in premixed DF combustion in a constant volume combustion chamber (CVCC). The entire DF combustion processes including methane gas injection, methane/air mixing, pilot diesel injection, and ignition are simulated. The numerical model is validated against experimental data. The present numerical model is able to capture the ignition delay time (IDT) within a maximum relative difference of 7% to the measurements. A higher relative difference of 38% is obtained when methane gas injection and mixing are omitted in the simulation and the methane/air is assumed homogeneous. This demonstrates the importance of inhomogeneity pockets. To study the effects of temperature and methane inhomogeneities separately, different idealized inhomogeneities in temperature and methane distribution are considered inside the CVCC. The inhomogeneity in the temperature is observed to have a more profound influence on the IDT than the methane inhomogeneity. The inhomogeneity pockets of temperature advance the first-stage ignition and, subsequently, the second-stage ignition. A sensitivity analysis on the effect of inhomogeneity wavelength reveals that the larger wavelengths enhance the combustion due to the presence of pilot diesel jets in the desirable regions for a longer time duration.

All-electric ships, and especially the hybrid ones with diesel generators and batteries, have attracted the attention of maritime industry in the last years due to their less emission and higher efficiency. The variant emission policies in different sailing areas and the impact of physical and environmental phenomena on ships energy consumption are two interesting and serious concepts in the maritime issues. In this paper, an efficient energy management strategy is proposed for a hybrid vessel that can effectively consider the emission policies and apply the impacts of ship resistant, wind direction and sea state on the ships propulsion. In addition, the possibility and impact of charging and discharging the carried electrical vehicles’ batteries by the ship is investigated. All mentioned matters are mathematically formulated and a general model of the system is extracted. The resulted model and real data are utilized for the proposed energy management strategy. A genetic algorithm is used in MATLAB software to obtain the optimal solution for a specific trip of the ship. Simulation results confirm the effectiveness of the proposed energy management method in economical and reliable operation of the ship considering the different emission control policies and weather condition impacts.

Ship designers face increasing pressure to comply with global emission reduction ambitions. Alternative fuels, potentially derived from bio-feedstock or renewable electricity, provide promising solutions to this problem. The main challenge is to identify a suitable ship power system, given not only uncertain emission requirements but also uncertain fuel and carbon emission prices. We develop a two-stage stochastic optimization model that explicitly considers uncertain fuel and carbon emission prices, as well as potential retrofits along the lifetime. The bi-objective setup of the model shows how the choice of optimal power system changes with reduced emission levels. Methanol and LNG configurations appear to be relatively robust initial choices due to their ability to run on fuel derived from different feedstocks, and their better retrofittability towards ammonia or hydrogen. From a policy perspective, our model provides insight into the effect of the different types of carbon pricing mechanisms on a shipowner's decisions.

Methanol, as one of the significant green fuel candidates for the combustion engines, can be produced from Power to X and biomass production. However, compression ignition (CI) of pure methanol in a combustion engine is impractical due to its low cetane rating. The strategy has gained little attention in the past, but is possible if the methanol is premixed with a fuel additive (ignition improver). In order to optimize and understand additivated methanol combustion, a phenomenological spray/packet combustion model is developed in this work. The model is used to calibrate an Arrhenius-type ignition delay equation for CI engine using additivated methanol, and the resulting calibrated ignition delay parameter is 2.14. The procedure involves to compare the modeled and experimental combustion rate profiles that are derived from a small marine CI engine by burning methanol with 3.5 % and up to 7.5 % kg/kg fuel additive. The present work finds that the phenomenological diesel combustion model methodology can be used with good accuracy, to simulate combustion rate profiles of additivated methanol in a CI engine. The model is, furthermore, able to indicate intermediate variables such as burning packet speeds, air mass, droplet mass, air/fuel equivalence ratio, and burning packet temperature for different packets of combustion.

Incumbent clinker production practices fall short of meeting carbon-emission neutral targets, pressing the need to implement waste valorization approaches in cement plants to mitigate environmental impacts. However, there is a lack of knowledge on the future environmental performance of emerging waste-to-heat and fuel upcycling in clinker manufacturing. This study examines the prospective life cycle impacts of (1) solid recovered fuel (SRF) utilization and (2) on-site marine fuel production using integrated fluidized bed pyrolysis to substitute fossil fuels in clinker production and marine transportation. Environmental impacts are projected between 2025 and 2050 by applying learning effects in the foreground life cycle inventory and shared socioeconomic pathways (SSP1, SSP2), extended with the 1.9 W m−2 representative concentration pathway (SSP2-RCP1.9), in the background system. The highest decarbonization progress (−538.9 kg CO2-eq (t clinker)−1) is achieved under the SSP2-RCP1.9 development trajectory, driven by avoidance of emissions from waste management systems and converting biogenic carbon-rich municipal solid waste resources. The predicted CO2-eq impacts are found to be lower than the point source emission from raw meal calcination in several SSP scenarios, indicating that carbon-emission neutrality is attainable in combination with retrofitted carbon capture, utilization, and storage (CCUS) technologies. The assessment highlights the potential for burden shifting to other environmental impacts, e.g., particulate matter formation (+37.0 % by 2050), pointing to the need to evaluate additional pyrolysis oil upgrading and NOX emission mitigation strategies. Overall, synergizing waste pyrolysis with clinker production is found to be favourable due to (i) improved energy requirements, (ii) reduced fossil fuel use and impacts on climate change and ecosystem quality, and (iii) high potential for technological learning-driven environmental progress.

Det Blå Danmark har en ambition om at være et internationalt foregangsland for klimavenlig skibsfart. Omstillingen til en mere bæredygtig skibsfart er dog en stor udfordring, der vil kræve betydelige investeringer i både ny teknologi, skibe og energiinfrastruktur og en systemisk tilgang til samarbejde på tværs af sektorer og mulige aftagere af grønne brændstoffer. Med denne rapport præsenterer DTU resultatet af et arbejde i at kortlægge forskningsmulighederne for Grønne Brændstoffer i det Blå Danmark. Arbejdet har afdækket, at der er behov for forskning på tværs af systemer og over hele værdikæden. Kortlægningen er lavet med viden fra DTU forskere samt input fra industrien og brancheorganisationerne.

Rapporten præsenterer en kortlægning af udfordringer forskningsbehov og rammebetingelser, som kan medvirke til at understøtte potentialet for grønne brændstoffer i det Blå Danmark. Kortlægningen er afrundet med anbefalinger til forskningsbehov inden for udvalgte områder samt uddannelse og test- og demonstrationsprojekter. Det er vores håb, at rapporten kan være med til at sikre det Blå Danmark en plads helt fremme i førerfeltet inden for bæredygtig skibsfart i mange år endnu.

Several replacement fuel to today’s fossil based ship propulsion fuels have been addressed in MarEfuel. Key ones are; pyrolysis oil (blend in fuel), methanol and ammonia. These were singled out among many possible fuels from a preliminary analysis that indicated that they could play a key role in fulfilling the emission targets set politically and by the sector in the most cost effective manner. In the following they shall be treated in turn in some detail. Costs of several “blue” fuels have also been assessed. The projected costs are used in other parts of the MarEfuel project (e.g. for assessing the total cost of ownership).