Decarbonizing construction machinery: Data-driven lifecycle assessment of a hydraulic excavator using electrified and alternative-fuel hybrid power systems

Decarbonizing the construction machinery sector is critical for global climate targets, yet the industry lacks comprehensive lifecycle assessments to guide its transition beyond conventional diesel. Existing studies often focus on operational performance, overlooking the lifecycle environmental impacts of promising electrification and alternative fuel pathways. This study bridges this gap by developing a high-fidelity lifecycle assessment (LCA) framework for a 21-ton hydraulic excavator, integrating powertrain efficiency models with load spectra constructed from real-world operational data. We systematically quantify the carbon footprints of grid-powered, battery-powered, diesel-hybrid, and methanol-hybrid systems. Key findings reveal that: (1) in stark contrast to passenger vehicles, the use phase dominates the excavator's carbon footprint, accounting for approximately 85% of total emissions, making battery production and retirement influential but not decisive. (2) among electrification pathways, grid-powered systems offer the highest lifecycle emission reduction (25.25%), followed by battery-powered (14.66%) and diesel-hybrid (7.56%) systems, with performance being highly dependent on the carbon intensity of the electricity grid. (3) methanol-hybrid systems present a critical trade-off, reducing use-phase emissions by 23.0% but increasing total lifecycle emissions by 57.9% when produced from fossil fuels. Our findings underscore a dual imperative for the sector's low-carbon transition: Optimizing the energy structure by greening the power grid and advancing fuel structure optimization through technologies like green methanol synthesis. This research provides crucial data-driven insights for robust decision-making in the sustainable transformation of heavy-duty machinery