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Geng et al. Carbon Footprints 2025, 4, 8 https://dx.doi.org/10.20517/cf.2025.02 Page 7 of 15

SUVs (S), and MPVs (M), with each divided into five segments: mini, small, medium, large, and
[30]
executive . In this study, these five segments were denoted by segment 1 to segment 5. The database also
includes both PHEVs and BEVs, with distinctions based on battery chemistry.

User behavior is a key factor in determining the V2G potential of EVs. This study constructed a city-level
EV commuting distance distribution database using statistical driving behavior big data . Additionally,
[31]
regional and temporal variations in temperature and policies significantly affect the results. TOU tariff
policies across regions define the periods of charging and providing PSVF services. Temperature influences
both real-time energy consumption and battery degradation. The 2023 city-level hourly average
temperatures and monthly provincial TOU tariff policies were compiled from available statistical data .
[32]

The life cycle inventories (LCI) of LIBs, including lithium iron phosphate (LFP) and nickel cobalt
aluminum (NCM) batteries, were sourced from the GREET model (2023 version) [33-35] , and those of EV
chargers were sourced from ECOINVENT database (version 3.8) . The LCIs of electricity were localized
[36]
based on the related report . In this study, it is assumed that NCM and nickel-cobalt-manganese (NCA)
[37]
batteries have the same emission intensities. Details of the aforementioned data are shown in the
Supplementary Material.

RESULT
Geographic heterogeneity of V2G’s additional GHG emissions in China
Figure 2 illustrates the additional GHG emissions of V2G technology in China. Figure 2A and B present the
results for providing FR and PSVF services, respectively. The results highlight significant geographic
heterogeneity in the LCE across the country. For FR services, the LCE values range from 0.046 to
0.152 kgCO /kWh. Southern and western regions exhibit lower LCE values, primarily due to the higher
2-eq
proportion of low-carbon renewable energy, such as wind and solar power, in the local grid. In contrast,
northeastern regions, which rely predominantly on fossil fuel-based power generation, exhibit higher
electricity GHG emission intensities, leading to relatively higher LCE values. For EVs providing PSVF
services, the overall LCE is lower than that for FR service, ranging from 0.036 to 0.148 kgCO /kWh. The
2-eq
regional distribution of LCE for PSVF services mirrors that for FR services, reflecting the influence of
regional differences in the power generation mix.

Figure 2C presents the results of ranking V2G’s additional GHG emissions based on LCE values. The
distribution of LCE values across cities is relatively uniform, with a few notable spikes due to the stepwise
increase in the provincial GHG emission intensities of electricity. By averaging the LCE values of different
cities according to the scale of local EV markets, the national average LCE of V2G technology is found to be
0.101 kgCO /kWh for FR services and 0.091 kgCO /kWh for PSVF services. The higher LCE for FR
2-eq
2-eq
services is primarily attributed to the frequent charging and discharging involved in grid scheduling, which
results in higher battery energy throughput and, consequently, more significant additional battery
degradation. This leads to a higher carbon footprint associated with battery materials and manufacturing.
The composition of additional GHG emissions for different V2G services will be further analyzed in the
subsequent sections.

Breakdown analysis of V2G’s additional GHG emissions in China
By aggregating the LCE results of V2G technology across cities and input data dimensions such as vehicle
type and battery chemistry, a comprehensive comparative analysis of LCE is obtained, as shown in Figure 3.
Specifically, Figure 3A shows the LCE breakdown with the results weighted by local sales data. The
comparison distinguishes PHEV and BEV powertrains, 5 types of battery chemistries, and 11 vehicle types