A Framework to Estimate Life Cycle Emissions for Vehicle-Integrated Photovoltaic Systems

Abstract

This paper presents a framework to estimate the environmental impact of solar electric vehicles, accounting for the emissions caused by photovoltaic system production as well as vehicle use. We leverage a cradle-to-gate life cycle assessment to estimate the greenhouse gas emissions of the vehicle-integrated photovoltaic system, from the raw material extraction to the final panel assembly, including the effect of the electricity mix both at the factory location and in the country of use. %the vehicle's life cycle, considering both Furthermore, we modify an existing optimization framework for battery electric vehicles to optimally design a solar electric vehicle and estimate its energy consumption. We showcase our framework by analyzing a case study where the mono-crystalline silicon extraction and refinement processes occur in China, while the final assembly of the panel is in The Netherlands, generating 118 kg of CO2 equivalents per square meter of solar panel. The results suggest that it is generally beneficial to operate solar electric vehicles in countries with a high irradiation index. However, when the local electricity mix already displays a low carbon intensity, the additional emissions introduced by the panel are unnecessary, requiring a longer vehicle lifetime to reach an advantageous emission balance.

Figures (8)

• Figure 1: The cradle-to-gate life cycle assessment estimates the environmental impact (in terms of equivalent kilograms of $\mathrm{CO_2}$) from the raw material extraction to the final panel assembly. In our framework, we also include the vehicle use phase emissions which depend on the powertrain design and its energy consumption.
• Figure 2: Global emissions by sector and sub-sector. Adapted from data in IEA2020IEA_global_21.
• Figure 3: Diagram including the system boundaries and the processes leading to the final assembly of the panel from the raw material extraction, considering energy and materials flows. Biosphere flows are direct emissions from a process (downstream), while technosphere flows are required for the production of the end product (upstream). The complete inventory is available in the database ClementevanSundert2024.
• Figure 4: Vehicle powertrain and energy consumption model, modified from ClementeSalazarEtAl2022.
• Figure 5: Single manufacturing processes contributions to the total GHGs per square meter of photovoltaic system production.