Lifecycle-aware microgrid design: quantifying embodied, operational, and avoided emissions in a grid-connected PV–Wind system

Abstract

This study develops a high-renewable hybrid microgrid integrating solar photovoltaic (PV), wind turbine (WT), and grid interaction for a university campus, with a distinctive focus on lifecycle emission performance. Using HOMER Pro-based optimization, the system achieves a low cost of energy (COE), that is, the average cost of producing one kilowatt-hour of electricity over the project lifetime, of $0.0218/kWh, together with a net present cost (NPC) of $523,143, an operating cost of $3,624/year, and a renewable fraction of 81.7%. The configuration reduces direct annual CO₂ emissions to 185,854 kg, corresponding to a 74.13% reduction compared to conventional grid-dominated supply. Beyond conventional techno-economic analysis, this work advances a cradle-to-grave lifecycle emission assessment. On a gross basis, counting embodied and operational emissions, the lifecycle emission intensity falls from 620 to 264.9 g CO₂-eq/kWh, a 57.3% reduction relative to the grid-only base case. When the renewable electricity exported to the grid under net metering is credited as avoided emissions, the net lifecycle intensity reaches 4.53 g CO₂-eq/kWh, corresponding to a 99.3% reduction, with embodied emissions recovered within 3.5 years. Both perspectives are reported to bound the environmental performance, and the sensitivity of the net benefit to progressive grid decarbonization is examined explicitly. Sensitivity analysis incorporating both meteorological and economic parameters confirms the robustness of the proposed design under uncertain conditions. The findings demonstrate that integrating lifecycle assessment with microgrid optimization provides a more comprehensive framework for sustainable energy planning, offering a scalable pathway toward ultra-low-emission campus electrification.