UK’s EV-elocity Project Offers Blueprint for China’s V2G Future
The electric vehicle revolution is no longer a distant vision; it is a roaring engine on the highway of the present. In China, this transformation is happening at a breathtaking pace. With nearly a million new energy vehicles rolling off production lines in 2023 and a charging infrastructure network swelling to nearly 8.6 million units, the nation is building the backbone of a new energy ecosystem. Yet, this monumental shift carries with it a profound challenge: the stability of the power grid. When hundreds of thousands of vehicles plug in simultaneously, the resulting surge in demand can strain, and potentially destabilize, the very system designed to power them. The solution, many experts believe, lies not in building more power plants, but in turning the vehicles themselves into mobile power stations. This is the promise of Vehicle-to-Grid, or V2G, technology. And while China races to deploy its own V2G pilots, a recently concluded project in the United Kingdom, known as EV-elocity, offers a treasure trove of practical lessons, hard-won data, and critical insights that Chinese policymakers, engineers, and entrepreneurs would be wise to study.
The EV-elocity project, funded by the UK government and running from 2018 to early 2022, was not merely a technical demonstration. It was a comprehensive, real-world social experiment designed to answer the most pressing questions about V2G: Does it truly benefit the environment? How does it impact the lifespan of an expensive EV battery? And crucially, will ordinary drivers actually use it? The project’s findings, meticulously documented and analyzed, reveal that the path to a successful V2G future is paved not just with advanced hardware and software, but with deep consideration for economic incentives, battery science, and human behavior.
At its core, V2G technology transforms the traditional, one-way relationship between an electric car and the grid. Instead of simply drawing power, a V2G-enabled vehicle can send power back. Imagine a fleet of parked EVs acting as a giant, distributed battery. During periods of peak demand or when renewable sources like wind and solar are underperforming, these vehicles can discharge stored energy to support the grid. Conversely, they can charge when demand is low and electricity is cheap—or, more importantly, when the grid is flush with clean, renewable energy. This bidirectional flow is a game-changer, offering a powerful tool to balance the grid’s peaks and valleys, integrate more renewables, and enhance overall system resilience.
The EV-elocity team understood that to prove this concept, they needed to move beyond the laboratory. They deployed V2G chargers across diverse real-world settings in the UK—from university campuses in Nottingham and Warwick to municipal car parks in Leeds. This geographical spread was intentional, ensuring the data collected reflected a wide array of user behaviors, grid conditions, and charging scenarios. The project was structured into four distinct, progressive phases, each designed to test a different aspect of V2G optimization.
The first phase was deliberately simple: uncontrolled, single-phase charging. Cars were plugged in and charged at maximum power until full, with no discharging allowed. This served as the baseline, the “business as usual” scenario against which all other strategies would be measured. The second phase introduced optimization, splitting into two sub-phases. In 2a, charging and discharging were scheduled based on fixed, time-of-use electricity tariffs—charging when power was cheapest and discharging when it was most expensive. In 2b, the goal shifted to minimizing carbon emissions, scheduling activities for times when the grid’s overall carbon intensity was lowest, typically during the night when renewable sources dominate. The third phase moved to dynamic, real-time optimization. Using an app called Crowd Charge, the system could adjust charging behavior based on live electricity prices (3a) or a 24-hour forecast of the grid’s carbon intensity (3b). Finally, the fourth phase focused squarely on the vehicle’s heart: its battery. The strategy here was to keep the battery’s state of charge (SOC) at around 50% for as long as possible, a level known to minimize “calendar aging,” the natural degradation that occurs over time even when the battery is not in use.
The results were illuminating. Both fixed and dynamic scheduling methods proved effective in reducing either costs or carbon emissions. Interestingly, the dynamic methods offered a slight edge, improving carbon reduction performance by about 3% compared to their fixed counterparts. However, the data also revealed a fundamental tension: a trade-off between optimizing for cost or carbon and protecting the battery’s health. Pushing the battery to discharge during expensive, high-carbon periods inevitably increased its wear and tear.
This leads to the project’s most critical area of research: battery degradation. For V2G to be commercially viable, consumers must be confident that participating won’t prematurely kill their car’s most expensive component. The EV-elocity team, led by researchers at the University of Warwick, undertook a rigorous analysis, modeling battery aging as a combination of two processes: “calendar aging” and “cycle aging.” Calendar aging is influenced by factors like storage temperature and the state of charge during periods of inactivity. Cycle aging, on the other hand, is driven by the number of charge-discharge cycles, the depth of those cycles, and the charging/discharging rate.
They tested five different charging strategies. “Standard Charging” (STD CHA) meant plugging in and charging to 100% immediately. “Time-Shifted Charging” (TS CHA) delayed charging so the car was full just before departure. “Smart Charge V1G” (SC V1G) optimized the charging schedule for cost or carbon but did not allow discharging. “Smart Charge V2G” (SC V2G) actively used the car for discharging, targeting the 50% SOC for minimal calendar aging. Finally, “Combined SC V1G and V2G” (SC VxG) attempted to balance both calendar and cycle aging factors.
The findings were nuanced and depended heavily on how often the car was used. For vehicles with low daily mileage, the aggressive discharging of the SC V2G strategy actually accelerated battery aging compared to simply plugging in and charging. In this scenario, the SC VxG strategy, which sought a balance, performed best. However, for cars driven more frequently, almost all the smart charging strategies outperformed the standard “plug-and-charge” method. Time-Shifted Charging and Smart Charge V1G offered the greatest improvement, extending battery life by nearly 15%, followed closely by the balanced SC VxG approach. This suggests that for the average commuter, smart charging—even without discharging—can be beneficial, while V2G participation requires more careful, balanced management to avoid undue harm.
Perhaps the most sobering, yet valuable, insights came from the project’s assessment of its own operational challenges and user feedback. The technical hurdles were significant. The V2G systems, being in their relative infancy, proved difficult to install and debug, requiring coordination across the entire supply chain and driving up costs. A particularly frustrating issue was system unreliability: if a car sat idle for too long without charging or discharging, it would go offline, requiring a manual remote restart to regain control. This is not a user-friendly experience.
User surveys painted a picture of cautious optimism mixed with practical frustration. Participants appreciated the environmental benefits and the potential for cost savings through dynamic pricing. They understood that their car could be a force for good, helping to stabilize the grid and reduce carbon emissions. However, their enthusiasm was dampened by real-world inconveniences. Some complained that in certain test phases, their car would only charge to 50% by morning, leaving them anxious about their daily range. Others found the charging schedules confusing and the lack of a clear, visual indicator showing when the car would be fully charged to be a major source of anxiety. In essence, the technology worked, but the user experience was often clunky and opaque.
Now, let’s turn our gaze to China. The nation’s ambition is clear. In January 2024, four major government agencies jointly issued an “Implementation Opinion on Strengthening the Integration and Interaction of New Energy Vehicles and the Power Grid.” This directive calls for large-scale V2G pilot demonstrations in mature regions like the Yangtze River Delta and Pearl River Delta, with a target of establishing more than five model cities and fifty bidirectional charging projects by the end of 2025. Projects are already underway in major metropolises like Beijing, Shanghai, and Shenzhen, involving not just private cars but also large public fleets like buses and taxis. The government’s financial and policy support is robust, and the focus is squarely on proving the technical feasibility of V2G—demonstrating that cars can charge and discharge, and that the grid can handle it.
This is a necessary and commendable first step. However, when measured against the comprehensive approach of the EV-elocity project, China’s current efforts reveal some critical gaps. The most significant is in scope and depth. While geographically dispersed, many Chinese pilots appear to be somewhat siloed, lacking the coordinated, multi-site, multi-scenario approach that gave EV-elocity its powerful, generalizable conclusions. The UK project, under the strong leadership of Cenex, created a unified framework where data from different locations fed into a common analysis, creating a much richer, more convincing dataset.
Furthermore, Chinese projects have, so far, paid relatively little attention to the very issues that EV-elocity identified as paramount: quantifying environmental value, deeply understanding battery degradation, and systematically gathering user feedback. Most studies offer qualitative praise for V2G’s green potential, but lack the sophisticated, data-driven models like EV-elocity’s REVOLVE model, which can simulate thousands of charging events over a year to calculate precise carbon and cost savings. Similarly, while battery health is a universal concern, Chinese research often treats it as a secondary issue, lacking the detailed, dual-model (calendar and cycle aging) approach that provides actionable insights for optimization.
This is not to diminish China’s achievements, but to highlight an opportunity. By learning from the UK’s experience, China can accelerate its own V2G development and avoid costly missteps. Here are four key recommendations for China’s path forward.
First, embed environmental value into the economic model. The EV-elocity project demonstrated that you don’t have to choose between saving money and saving the planet. Their “combined optimal” strategy, which treated carbon emissions as a cost by applying a “carbon price,” showed that even a modest carbon price can trigger significant emissions reductions without sacrificing economic efficiency. At the UK’s real-world carbon price, this approach yielded over 180 kg of CO2 savings per vehicle per year. China should adopt a similar framework. By integrating carbon pricing into the charging cost calculation for V2G participants, the system can automatically steer behavior towards low-carbon periods. This turns every EV driver into a climate actor, aligning individual economic incentives with national carbon neutrality goals.
Second, accelerate the development of a unified, enforceable standards ecosystem. The success of any large-scale, interoperable technology hinges on standards. In the US, particularly in California, authorities have aggressively pushed for standardization, endorsing specific communication protocols like ISO 15118 for vehicle-charger interaction and OCPP for charger-platform communication. This creates a level playing field and gives businesses the confidence to invest. China is making progress with its forward-looking ChaoJi charging standard, but a comprehensive V2G standard system—covering everything from communication protocols to safety requirements and data formats—is still in its infancy. The government must take a more proactive role, not only in developing standards but also in rigorously enforcing them. This requires establishing a clear regulatory body and fostering collaboration among industry consortia, research institutions, and private companies to build a truly unified and mature standard system.
Third, make battery health a central pillar of V2G strategy, not an afterthought. The fear of battery degradation is perhaps the single biggest barrier to widespread V2G adoption. China must invest heavily in research that mirrors the depth of the EV-elocity project. This means developing and validating sophisticated battery aging models that account for both calendar and cycle effects under real-world Chinese driving and climate conditions. Beyond pure research, practical mitigation strategies must be deployed. This includes optimizing charging algorithms to avoid extreme states of charge, managing battery temperature through advanced thermal systems, and limiting the depth and frequency of discharge cycles. Crucially, automakers and V2G service providers need to offer consumers tangible reassurance. This could come in the form of extended “V2G-specific” battery warranties, financial compensation based on the amount of energy discharged, or discounts on future battery replacements. If consumers feel protected, they will be far more willing to participate.
Fourth, and perhaps most importantly, prioritize user experience and acceptance. Technology, no matter how brilliant, fails if people don’t want to use it. The frustrations reported by EV-elocity participants—confusing schedules, lack of transparency, system unreliability—are universal. China must design its V2G systems with the user at the center. This means creating intuitive, visually clear mobile apps that show users exactly when their car will be charged, how much money they’ve saved, and how much carbon they’ve offset. It means offering simple, compelling economic incentives, such as highly favorable “V2G participation” electricity rates or direct cash rewards for providing grid services. It also means launching comprehensive public education campaigns to demystify V2G, explaining its benefits not just for the individual, but for the community and the environment. To truly understand and predict user behavior, China should also invest in advanced data analytics, using machine learning to model and anticipate how different incentives and interface designs will influence participation rates.
The road ahead for V2G in China is long, but the destination is clear: a future where millions of electric vehicles don’t just consume energy, but actively manage and stabilize it. This future promises a more resilient grid, a faster transition to renewable energy, lower electricity costs for consumers, and a significant contribution to the nation’s “dual carbon” goals. The UK’s EV-elocity project has provided a detailed map for part of this journey. It has shown that success requires more than wires and software; it demands a holistic approach that harmonizes technology, economics, environmental science, and human psychology. By embracing these lessons, China can not only catch up to global leaders in V2G but potentially leapfrog them, building the world’s most advanced and user-friendly vehicle-to-grid ecosystem. The electric vehicles are here. It’s time to unlock their full potential.
By Zhang Zhanlong, Du Jian, Zheng Jiaqi, Wang Weiliang, Gao Shan, Yang Yue, Yan Kai, Jiang Tianwei. Published in Power Demand Side Management, Vol.26, No.4, July 15, 2024. DOI: 10.3969/j.issn.1009-1831.2024.04.007.