Fuel consumption and emission reduction of marine lean-burn gas engine employing a hybrid propulsion concept

Abstract

As the emission legislation becomes further constraining, all manufacturers started to fulfill the future regulations about the prime movers in the market. Lean-burn gas engines operating under marine applications are also obligated to enhance the performance with a low emission level. Lean-burn gas engines are expressed as a cleaner source of power in steady loading than diesel engines, while in transient conditions of sea state, the unsteadiness compels the engine to respond differently than in the steady-state. This response leads to higher fuel consumption and an increase in emission formation. In order to improve the stability of the engine in transient conditions, this study presents a concept implementing a hybrid configuration in the propulsion system. An engine model is developed and validated in a range of load and speed by comparing it with the available measured data. The imposed torque into the developed engine model is smoothed out by implementing the hybrid concept, and its influence on emission reduction is discussed. It is shown that with the hybrid propulsion system, the NOX reduces up to 40% because of the maximum load reduction. Moreover, eliminating the low load operation by a Power Take In during incomplete propeller immersion, the methane slip declines significantly due to combustion efficiency enhancement.

Transient Performance of Gas-Engine-Based Power System on Ships: An Overview of Modeling, Optimization, and Applications

“…Moreover, they mainly focused on the steady states as discussed in [52,133]. Despite the main scope of reducing fuel consumption, a gas engine load trace with more minor fluctuations has been obtained by using a hybrid power design, as reported in [27]. Sun et al [134] investigated the system's transient behavior during the modes switching of a real gas engine, and the experiment result shows a shorter power system response time, demonstrating that dynamic compensation can be achieved by the hybrid concept.…”

“…At the same time, more applications have been reported for energy storage systems (ESS) on ships over recent years, particularly involving batteries in hybrid power systems. When combined with the combustion engines, ESS contributes to power shifting and optimized engine working points to improve system fuel efficiency in most scenarios [27][28][29]. Because of the low energy density of batteries, their primary application has been in smallcapacity scenarios [30][31][32].…”

Review of the IMO Initiatives for Ship Energy Efficiency and Their Implications

“…This can help to select an optimum propeller based on the system configurations to operate at the engine operating point with minimum fuel consumption, which can help to reduce the amount of fuel consumed along the ship trip with different weather conditions while complying with the cavitation, strength and noise issues (Tadros et al, 2021a;Ghaemi and Zeraatgar, 2021;Tavakoli et al, 2021;Tadros et al, 2022e;Tadros et al, 2022b;Tadros et al, 2023b). The use of empirical formulas shows its effectiveness in reaching the optimal solution in a few minutes with high accuracy.…”

Thermodynamic Analysis and Comparison of Two Marine Steam Propulsion Turbines

“…The new technologies and improvements, especially in the fi eld of harmful emissions reduction due to stringent legislation aff ects also marine diesel engines [10][11][12]. The legislation related to harmful emissions [13,14] was the reason that conventional diesel engines are being more and more replaced by dualfuel engines whose operation (especially in the gas operating mode) notably reduces emissions [15][16][17]. Also, the process of dual-fuel engines is still improving each day intending to obtain optimal operation [18][19][20].…”