Electric vehicles should become a vital component of future energy storage systems.

New energy systems are rapidly developing globally, with electric vehicles being a key component. The transportation sector, heavily reliant on oil, faces greater challenges in achieving a low-carbon transition than other sectors. Replacing fuel-powered vehicles with electric vehicles is a key path to this transition. In fact, as electric vehicles expand in scale, they will not only support the transportation sector's low-carbon transition but also serve as energy storage to smooth out peak demand in the power grid, improving energy system efficiency and reducing costs.

Electric vehicles can contribute to addressing the instability of wind and photovoltaic power generation in two ways: First, they can be charged during nighttime lows and discharged during daytime peaks, achieving peak-shaving and valley-filling through complementary and substitutional energy. Second, retired power batteries can be recycled for energy storage. Repeated charging and discharging reduces the battery's range. When the battery capacity drops to 60%-70% of its rated capacity, it becomes unsuitable for meeting commuter needs. There are many potential uses for retired power batteries, the most important of which is their recycling as energy storage in distributed or centralized wind and photovoltaic power plants. Electrochemical energy storage generates pollution both during its production and end-of-life phases. Compared to electrochemical energy storage, future electric vehicle participation in energy storage may offer lower costs and lower pollution. Specifically, developing the energy storage capabilities of electric vehicles can promote the absorption of wind and photovoltaic power and improve grid efficiency, primarily in the following ways:
First, as electric vehicle penetration increases, the number of power batteries will also grow rapidly. This scale effect makes the integration of electric vehicles into energy storage systems feasible and economical. Whether electric vehicles can effectively participate in peak and frequency regulation as energy storage systems depends primarily on whether they possess sufficient scale benefits to truly play a key role in regulating grid load. By the end of 2021, the number of electric vehicles in China reached 7.84 million. Assuming an average power battery capacity of 40 kWh (the 2021 Tesla Model 3 has a battery capacity of 60 kWh, and the BYD Han has a capacity of over 60 kWh), retired electric vehicles can provide approximately 200 GWh of energy storage capacity. Currently, electric vehicles account for only 2% of China's total vehicle ownership and account for approximately 0.1% of residential electricity consumption. Therefore, using electric vehicles to regulate residential electricity load is unlikely to have a significant impact. As the market share of electric vehicles rapidly increases in the future, their load regulation role will gradually become more apparent. According to the "Energy-Saving and New Energy Vehicle Technology Roadmap 2.0," by 2030, new energy vehicles will account for 40% to 50% of total vehicle sales in China. By then, the potential for electric vehicles to participate in grid peak and frequency regulation as energy storage will increase more than tenfold. Assuming that wind and photovoltaic installed capacity will reach over 1.2 billion kilowatts by 2030, the growth rate of electric vehicles will outpace that of wind and photovoltaic power. If electric vehicles can fully leverage their energy storage capabilities in load shifting and battery cascade utilization, they will have a significant positive impact on the development of wind and photovoltaic power.

Secondly, to accommodate the rapid growth of wind and photovoltaic power, the proportion of energy storage must be rapidly increased. Electric vehicles may become an important medium- to long-term supplement to electrochemical energy storage. Currently, wind and photovoltaic peak-shaving stabilization services are primarily provided by thermal power and pumped hydroelectric storage. In the process of achieving carbon neutrality, coal-fired power will gradually shift from its traditional dominant role in power supply to supporting peak-shaving services. However, coal-fired power's peak-shaving role is primarily focused on addressing relatively large seasonal fluctuations in electricity demand. It offers relatively limited flexibility in balancing power supply and demand and responding to extreme unexpected situations, and the cost of increasing peak-shaving flexibility is high. Pumped-storage power stations are subject to natural resource constraints, and their potential for development is relatively limited. Against this backdrop, building electrochemical energy storage systems that complement the development of wind and photovoltaic power generation is essential for future clean energy systems based on wind and photovoltaic power. However, electrochemical energy storage is relatively expensive and has a limited lifespan. Its production and recycling processes generate significant pollution emissions. Theoretically, electric vehicle batteries of sufficient scale can perform similar energy storage functions as electrochemical energy storage systems, potentially at a lower cost.

Third, as electric vehicle market penetration increases, the energy storage function of electric vehicles can be leveraged by guiding and regulating consumer charging behavior. The growth in the number of electric vehicles will lead to a significant increase in electricity consumption. According to expert calculations, a 1% increase in electric vehicle market share will result in an annual increase in electricity consumption of 23.65 GWh. The charging load of electric vehicles and residential electricity load are not completely complementary. When a large number of electric vehicles are connected to the grid, peak-to-peak charging increases the risk of power shortages and poses challenges to the stable operation of the power system.

According to research reports, the peak period of residential electricity load on a typical day occurs between 10:00 AM and 8:00 PM, with the lowest point occurring between 1:00 AM and 7:00 AM. On a typical day, there are three peak charging times for electric vehicles: 8:00 AM, 3:00 PM, and 11:00 PM. The complementarity between electric vehicles and residential electricity load is primarily reflected in the fact that electric vehicles can charge at off-peak prices at night. Given the current low level of electric vehicle ownership, this can help balance the load. If electric vehicles become increasingly popular in the future, the concentrated charging of residents at 3:00 PM could potentially make this time a new peak in electricity demand, increasing pressure on the grid and increasing electricity costs. Therefore, the government needs to formulate effective peak-off-peak time-of-use electricity pricing to guide and regulate electric vehicle charging times to avoid peak-to-peak charging, which increases electricity costs. Effective peak-off-peak time-of-use pricing, combined with guidance and regulation of charging behavior, can fully leverage the energy storage capabilities of electric vehicles and achieve a rational shift in electricity load.

Fourth, cascading the utilization of retired power batteries can maximize their utilization. With the rapid growth in electric vehicle production and sales, the number of retired power batteries is also expected to increase rapidly (currently, their lifespan is approximately 5 to 8 years). Improper disposal can lead to environmental pollution. Furthermore, retired power batteries generally retain 80% of their rated capacity, allowing for multi-scenario reuse and promoting a circular economy. Currently, the cascade utilization of power batteries is still in the exploratory phase, and a complete industrial chain has yet to be established. After remaining capacity is tested, retired power batteries can be used in low-rate power supply scenarios, such as as energy storage power sources, acting as backup power sources for homes and workplaces. They can also be combined with peak and off-peak electricity prices to achieve arbitrage and profit. Centralized power batteries can be directly used to store energy in wind and photovoltaic power plants, supporting grid integration and consumption. Furthermore, cascade utilization of retired power batteries can replace electrochemical energy storage in the ancillary services market, reducing demand for electrochemical energy storage and thus conserving resources and protecting the environment.

Reprinted from Sina Auto

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