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into the grid could reduce overall GHG emissions by up to 25%, with further reductions expected as
[15]
renewable energy penetration increases . Wang et al. incorporated EVs with V2G into an energy system
model and analyzed its impacts on GHG emissions. The results highlighted that, despite the increased use of
EV batteries, V2G still offers a positive impact on overall GHG emissions compared to random and
uncoordinated EV charging . Noori et al. assessed the GHG emission reduction potential of V2G
[16]
technology across five U.S. independent system operators, finding that V2G could help specific regions
reduce CO emissions by up to 500,000 tons by 2030 . Based on existing research, the large-scale
[17]
2
application of V2G technology contributes to advancing the low-carbon transformation of the power
system and effectively reduces overall GHG emissions in the power system.

While using EVs as distributed energy storage resources facilitates the integration of renewable energy and
supports the decarbonization of the power system, it is important to recognize that, from a life cycle
assessment (LCA) perspective, providing electricity through energy storage systems inevitably incurs
additional GHG emissions compared to directly drawing electricity from the grid, which could reduce the
potential of energy storage systems for decarbonizing the power system. Additional GHG emissions from
energy storage systems stem from the materials and manufacturing of related equipment, as well as
electricity losses due to the round-trip efficiency in charging and discharging processes [18,19] . Existing studies
have already assessed the additional GHG emissions of stationary energy storage systems. Fares et al.
[19]
evaluated the additional GHG emissions from home energy storage in residential solar energy systems .
The results showed that storage operation could increase household annual emissions by 153-303 kg CO ,
2
0.03-0.20 kg SO , and 0.04-0.26 kg NO , respectively. Schmidt et al. quantified the additional lifecycle GHG
x
2
emissions of various battery storage technologies when providing grid services, highlighting that lithium-
ion batteries (LIB) exhibit the best lifecycle emissions (LCE) . Hittinger et al. analyzed the additional GHG
[20]
emissions resulting from the application of bulk energy storage in the United States, estimating that
deploying such systems across different regions would lead to additional CO emissions of
2
104-407 kgCO /MWh . However, existing studies have not accounted for V2G technology. As a
[21]
2-eq
promising energy storage solution, it is crucial to evaluate the additional GHG emissions of V2G
technology.
This study focuses on addressing two key gaps in the existing literature. First, in response to the lack of a
systematic analysis of the additional GHG emissions associated with V2G technology, we developed an LCA
model specifically for V2G technology. We first constructed a V2G technical model to simulate the
operation of EVs when participating in V2G. Based on the technical model, we then quantified the
additional lifecycle GHG emissions associated with V2G technology. Furthermore, China, with the largest
EV market globally, holds significant potential for V2G applications. Due to notable differences in EV
market structures, external environments, and electricity market policies across various regions in China,
the GHG emissions of V2G technology exhibit substantial geographical heterogeneity. Therefore, this study
focuses on the Chinese EV market, analyzing the geographical variation in the additional GHG emissions of
V2G technology across 337 cities using high-resolution data on the EV market and driving behaviors. This
research contributes to a comprehensive understanding of the carbon emission impacts of V2G deployment
and provides a theoretical foundation for the future regional development of V2G technology in China.

METHOD
To evaluate the additional GHG emissions of V2G technology, this study developed an LCA model based
on the operational mechanisms of EVs within the V2G framework. The system boundary is shown in
Figure 1A, including the materials and manufacturing of related equipment, as well as electricity losses
resulting from the round-trip efficiency of battery charging and discharging, while excluding the GHG