• Energy Research

Abstract Marine diesel engines are one of the most representative fossil fuels consumers on the planet. These engines are responsible for a large amount of air pollutants, including greenhouse gas emissions. This concern led to the adoption of new regulations and policies for shipping, which involved more intensive restrictions for airborne emissions. This scenario, in addition to the finite fossil fuel reserves, the fluctuating price of fossil fuel and its share of the annual costs of ships, has boosted the development of new alternative fuels for marine diesel engines from traditional ones. It is known that waste oils are one of the most abundant residues generated within the industry. This study assesses the technical suitability of an alternative fuel oil, obtained from recycled waste automotive lube oil, in comparison with traditional fuels, complying with the ISO 8217 for distillate fuel oils. The alternative fuel was tested on a full scale marine diesel engine test bench, simulating real operating conditions for marine diesel engines and electric diesel generators in steady loads. To this end, the engine was cooled with sea water and coupled to a hydraulic brake, which allowed tests to be undertaken in different engine loads and propulsion modes, such as controllable and fixed pitch propeller propulsion systems. The results demonstrated that the alternative fuel burns rapidly but with a delay at the end of combustion, which should be expected for this type of fuel. Additionally, the energy efficiency of the diesel engine is comparable to the distillate fuel commonly used by the fishing fleet; however, due to its higher heating value, the alternative fuel presents lower fuel consumption. According to the emissions, the alternative fuel exhibits lower NOx and CO2 emission levels but slightly higher CO emissions and smoke opacity levels than common fuels, with the sulphur content in the fuel below the maximum level being allowable by more stringent marine rules. Hence, waste oil-based alternative fuel oils are acceptable for use in marine diesel engines operated on-board a ship under real conditions and meet the rules applicable to marine environments for burning fuel oils.

The current paper presents the design and energy performance analysis of a propane-based reversible Dual Source/Sink Heat Pump (DSHP). DSHPs offer an alternative to conventional water to water and air to water heat pumps, leveraging the strengths of both technologies in an efficient manner. The developed prototype incorporates an innovative Dual Source/Sink Heat eXchanger (DSHX), enabling the unit operating in various modes, including space heating, space cooling, and domestic hot water production using brine, air or both simultaneously as a source/sink. The DSHX serves as as both a condenser or an evaporator, directly rejecting or absorbing heat from air and/or brine. By eliminating secondary loops and defrost cycles, the DSHX minimizes energy losses. The main novelty of this work lies in the DSHX that integrates external units typically duplicated in DSHPs into a single component, eliminating the need for split refrigerant flow rates, thus avoiding maldistribution, refrigerant charge increase and draining valves. A steady state experimental campaign was conducted in a climatic chamber to characterize the DSHP prototype and validate the DSHX performance models. Heating capacity up to 11.2 kW and COP values up to 4.7 were achieved at nominal compressor speed by supplying hot water at 35 °C with an ambient temperature of 7 °C. Similarly, when producing cold water at 7 °C, cooling capacity and EER reached 9.8 kW and 3.6, respectively, at nominal compressor speed using air as heat sink at 35 °C. The effects of various operating parameters on the overall coefficient of performance and heat duty in both heating and cooling modes, considering air or brine as heat source/sink are analyzed in detail. Results demonstrate enhancements of approximately 15 % in capacity and efficiency compared to earlier work. Moreover, four deterministic models were created in order to predict the behaviour of the DSHX and validated against experimental results, reaching deviation values below 15 %. The authors would like to thank the support of the TRI-HP project (https://www.tri-hp.eu/project) funded by the European Union's Horizon 2020 research and innovation programme, Project No. 814888.

Sustainability is one of the main challenges of commercial fishing. Fuel represents almost 40% of the total cost of a fishing vessel. The increase in the price of fuel over the last decade, together with the volatility and fluctuation in the price for a barrel of crude oil, makes fuel costs one of the main concerns of ship-owners. As a response, different initiatives have been undertaken, with the aim to reduce such fuel dependency. The present contribution presents the feasibility study of the use of different magnetic devices for fuel treatment, in order to improve the energy efficiency of fishing vessels and reduce exhaust emissions. According to manufacturers, fuel treatment devices provide three effects: reduction in fuel consumption; reduction in exhaust gas emissions; and improvement of engine performance by reducing maintenance costs. Three independent magnetic devices have been mounted and tested on three different 4 stroke compression ignition diesel engines. The first device was tested in an engine located on a test bench; it was operated under controlled laboratory conditions. The second, installed on board a trawler fishing vessel operating in the Mediterranean Sea; and the third, on board a representative vessel of the trolling fishing fleet operating in the Bay of Biscay and Atlantic Ocean. In all cases, the potential fuel-saving (~2%) and exhaust gas emissions (~0.6%) reduction was lower than expected by manufacturers. The aim of this contribution is to provide ship-owners with scientific knowledge to make informed decisions, when investing in energy-saving technologies.

Abstract Commercial fishing is heavily fuel dependant. The increase in the fuel price, together with the stock decline, occupational risks of fishing, the possibilities of finding a different future for new generations, are some of the reasons that have made fishing arrive at its ‘survival limits’, in many parts of Europe. This contribution aims at providing shipowners and researcher with the experience of undertaking energy audits, to reduce the fuel bill of fishing vessels. In order to do so, 3 fishing vessels were assessed comprehensively, for 2010–2012, to determine their energy consumption flow. The results indicate that energy consumption depends upon: (a) the structure and size of the vessel; (b) the engine conditions and use patterns; (c) the fishing gears used; (d) the fishing and trip patterns; (e) the distance to the fishing ground; (f) target species and their migration routes; and (g) the traditions onboard. Likewise, no generalisation can be made regarding the way energy is consumed by onboard equipment/machinery when different fishing gears are compared. Energy audits will need to be site-specific and to include sufficient data to obtain representative results; these are likely to be more than in land-based industries, due to the peculiarities of this sector.

Abstract. A reliable and up-to-date maritime emission inventory is essential for atmospheric scientists quantifying the impact of shipping. The objective of this study is to estimate the atmospheric emissions of SO2, NOx, CO2 and PM10 by international merchant shipping in 2007 in the Strait of Gibraltar, Spain, including the Algeciras Bay by two methods. Two methods (both bottom-up) have been used in this study: 1. Establishing engine power-based emission factors (g kWh−1, EPA) or the mass of pollutant per work performed by the engine for each of the relevant components of the exhaust gas from diesel engines and power for each ship. 2. Establishing fuel-based emission factors (kg emitted/t of fuel) or mass of pollutant per mass of combusted fuel for each of the relevant components of the exhaust gas and a fuel-consumption inventory (IMO). In both methods, the means to estimate engine power and fuel-consumption inventories are the same. The exhaust from boilers and incinerators is regarded as a small contributor and excluded. In total, an estimated average of 1 389 111.05 t of CO2, 23 083.09 t of SO2, 32 005.63 t of NOx and 2972 t of PM10 were emitted from January 2007 until December 2007 by international and domestic shipping. The estimated total fuel consumption amounts to 437 405.84 t. The major differences between the estimates generated by the two methods are for NOx (16% in certain cases) and CO (up to 23%). A total difference for all compounds of 3038 t (approximately 2%) has been found between the two methods but it is not areasonable estimate of uncertainty. Therefore, the results for both methods may be considered acceptable because the actual uncontrolled deviations appear in the changes in emission factors that occur for a given engine with age. These deviations are often difficult to quantify and depend on individual shipboard service and maintenance routines. Emission factors for CO and NOx are not constant and depend on engine condition. For example, tests conducted by the authors of this paper demonstrate that when an engine operates under normal in-service conditions, the emissions are within limits. However, with a small fault in injection timing, the NOx emission exceeds the limits (30% higher value in some cases). A fault in the maintenance of the injection nozzles increases the CO emission (15% higher value in some cases).

Abstract This paper examines the role of marine engine maintenance in reducing pollution. It tests four marine diesel engines, one constructed prior to January 1, 2000 and three after 2000. This paper explains how the condition of an engine’s nozzles and faulty injection pressure significantly influence NOx and CO emissions and describes both bench and onboard ship tests, on engines fitted with new or worn nozzles at different injection pressures. The tests showed that, when the engine constructed prior to 2000 operates under normal in-service conditions, the emissions are within limits, but, with a small fault in injection timing, the NOx emissions exceed the limits. For the engines constructed after 2000, a fault in the maintenance of the nozzles increases the CO emissions to a high level.