• Solketal showed reduced soot formation and a slightly longer ignition delay. • The hydroxyl group likely contributes to solketal’s greater oxidative activity. • Solketal enhances fuel oxidation under low injection energy conditions. • Biodiesel–solketal blends confirm solketal’s oxidation-promoting effects. • Diesel R33 showed the best behavior at 3 wt% solketal, revealing a non-linear effect. The global energy transition drives an enhanced emphasis on innovative fuel design approaches. Novel renewable fuel components are being sought that are drop-in compatible and exhibit synergistic interactions within fuel components. Isopropylidene glycerin (solketal) is a promising candidate, offering favorable chemical and physical properties due to its high molecular oxygen content. This study investigates the soot formation tendency and ignition behavior of solketal in a high pressure and high temperature injection chamber. Its combustion characteristics under varying injection parameters and chemical influences were evaluated in comparison with 1,3-dioxolane and a reference fossil diesel fuel. Additionally, the influence of solketal in a binary biodiesel-solketal system and in Diesel R33 was examined. Solketal exhibited a soot-reducing effect alongside an increased ignition delay. Comparison with 1,3-dioxolane suggests that the enhanced oxidative reactivity is attributable to the hydroxyl functionality. This interpretation is supported by low-temperature combustion indicators and observations in the biodiesel-solketal system. The Diesel R33 results showed that a concentration of 3 wt% solketal provides the most favorable performance characteristics. This demonstrates how targeted blending strategies can unlock beneficial combustion effects. Such insights open promising pathways for developing advanced, future-ready fuel formulations

• Power profile synthesis via a probability-based downsampling method. • Energy system design and lifetime cost optimization, ensuring vessel stability. • Model includes combinatorial placement decisions for energy systems and ballast. • Use of advanced MINLP solver (SCIP). • Fuel costs: 74.2%, CAPEX: 24.5% of total lifetime energy system costs. Low total lifetime cost is essential for the adoption of zero-emission ship energy systems, which must meet operational power demands while complying with onboard safety regulations. However, many studies rely on a simplified, averaged or insufficiently representative load profile and treat system design, operation, and integration feasibility separately, which can distort lifetime cost assessments and result in practically infeasible retrofit concepts. This study investigates how a hydrogen-based ship energy system can be optimally sized, operated, and arranged onboard to minimize total lifetime cost while satisfying operational constraints and stability requirements for a general cargo vessel retrofit. A representative power profile is synthesized from one year of operational data using a probability-based downsampling method and then used in a mixed-integer nonlinear lifetime cost optimization with discrete placement and ballast decisions, solved using the SCIP solver. The optimal retrofit comprises 1.4 MW of fuel cells, 180 kWh of batteries, and a 146 m 3 liquefied hydrogen (LH 2 ) tank, requires 171 t of ballast to satisfy trim and vertical stability constraints, and is primarily driven by fuel costs, which account for 74% of the total lifetime cost. Overall, the results indicate that the viability of hydrogen-based ship retrofits primarily depends on LH 2 storage integration constraints and hydrogen price assumptions, and that the proposed framework provides a practical basis for lifetime cost assessment of feasible retrofit designs.