Electric Vehicle Charging Station Infrastructure, Policy Impact, and Future Trends
A major shift has occurred globally as transportation moves from fossil fuel-driven to zero-emission and ultra-low tailpipe emission vehicles. The transition to electric vehicles (EVs) requires charging station (CS) infrastructure integrated with information technology, smart distributed energy generation installations, and favorable government policies. This paper discusses the key factors in planning charging infrastructure for electric vehicles. It provides information on planning and technology developments that can be used to improve the design and implementation of charging station infrastructure. A comprehensive review of the current electric vehicle landscape, the impact of electric vehicles on grid integration, and the optimal configuration of electric vehicle supply is presented. In particular, this paper analyzes the research and development related to charging station infrastructure, the challenges it faces, and efforts to standardize infrastructure to enhance future research initiatives. Furthermore, the optimal location of fast charging stations is discussed, focusing on economic benefits and grid impact. It also addresses the challenges associated with adoption. On the other hand, future trends in this field, such as energy procurement from renewable sources and the benefits of vehicle-to-grid (V2G) technologies, are presented and discussed.
Optimal charging scheduling techniques can leverage the flexibility of electric vehicles as loads while minimizing the impact of solar and wind energy systems on the grid. The current study shows that the use of metaheuristic techniques combined with optimization software can significantly improve the efficient use of available resources. These tools can be used to plan and manage EV charging infrastructure, including identifying the best locations for charging stations and determining optimal charging schedules. Mobile charging stations provide EV owners with peace of mind, ensuring access to charging facilities when a nearby charger is unavailable, which is an integral part of planning EV charging infrastructure. Using V2G technology, energy can be exchanged bidirectionally, providing ancillary services to the grid. Having a charging infrastructure with minimal charging time is essential for the widespread adoption of EVs. To minimize the impact on the main grid, battery swap stations regulate the charging schedule of the EV battery packs. In addition, they can serve as backup units to provide power to the grid during peak demand. With the development of electric vehicles and their charging infrastructure, coupled with the use of renewable energy, harmful emissions in the transportation sector can be significantly reduced. Unfortunately, the potential environmental impacts of this new infrastructure have not yet been fully evaluated. In future electric vehicles, hydrogen and fuel cells may replace the batteries currently used in battery energy storage systems.
As an alternative technology among various developed technologies, electric vehicles have gained significant room for development and have become an integral part of modern transportation. Electric vehicles are generally classified into three categories based on the source of electricity for vehicle propulsion (based on Miele et al. (2020) and Thompson et al. (2018)):
- Hybrid Electric Vehicles (HEV)
- Plug-in Electric Vehicles (PEV)
- Fuel Cell Electric Vehicles (FCEV)
Every electric vehicle comes with a Level 1 (L1) charging cord. This device is universally compatible, requires no installation fee, and plugs into any standard grounded 120-volt outlet. Depending on the price of electricity and the efficiency of the electric vehicle, L1 charging costs can range from $2 to $6 per mile. L1 chargers have a maximum power rating of 2.4 kW and a charging rate of 5 miles per hour, which works out to about 40 miles every 8 hours. For many people, this charging method works well, as the average driver drives 37 miles per day. L1 chargers also benefit those whose workplaces and schools offer L1 charging points, as they can charge their electric vehicles throughout the day. However, since L1 charging is not sufficient for long commutes or weekend driving, EV drivers often refer to this method as "emergency charging" or "trickle charging." Typical household outlets conduct L1 charging at 120 V, with a maximum current of 16 amps. This charging point offers a maximum power output of 1.9 kW, and it takes 8 to 16 hours to fully charge the battery, depending on the battery capacity. The SAE J1772 connector is used to connect the EV to the charging column. While L1 charging has the lowest charging cost, it is also the slowest. When combined with a rate-based charging system, L1 charging can further reduce charging costs.
Level 2 (L2) charging stations are most commonly used in public and residential locations. To meet L2 requirements for electric vehicles, charging stations must use 240 V single-phase power (for residential and commercial facilities) with a maximum current capacity of 40 A; charging stations for public areas must use 400 V three-phase AC power (maximum current capacity of 80 A). Level 2 chargers typically cost between $500 and $2,000 per unit, depending on the brand, power rating, and installation requirements. L2 charging costs range from $2 to $6 per mile, depending on electricity prices and vehicle efficiency. In addition to public L2 charging stations in parking lots, there are also charging stations at the entrances of businesses, schools, and universities used by students and employees. Electric vehicles equipped with industry-standard J-type plugs are generally compatible with SAE J1772 charging stations. The maximum charging power of L2 charging stations is about 12 kW, which equates to charging about 100 miles every 8 hours. For the average driver who drives 37 miles per day, the charging time is about 3 hours. If your driving distance exceeds the vehicle's range, L2 charging stations can provide fast charging along the way (Tan et al., 2016). In addition, L2 charging stations facilitate faster charging and are equipped with built-in overcurrent and overvoltage protection.
The fastest way to charge electric vehicles is Level 3 (L3). L3 charging stations are mainly located in public and commercial areas. Due to their fast charging capabilities, vehicles can be quickly charged in high-traffic areas such as rest stops, shopping malls, and entertainment areas. Charging may be based on time or energy consumption (kilowatt-hour). The cost of L3 charging can range from $12 to $25 per mile, depending on membership fees and other factors. Additionally, L3 chargers do not meet industry standards and are not universally compatible. By using DC charging technology, these stations provide a user experience similar to traditional gas stations. Using DC fast charging, the battery can charge from 0 to 80% in approximately 15 to 20 minutes. Regardless of the charge level, the final 20% of the battery is always charged in slow mode. DC power is delivered to the electric vehicle by converting AC power from an off-board charger. The charging voltage for L3 stations is typically between 200 and 600 V, and the output power ranges from 36 to 240 kW. According to SAE standards, DCFC can be divided into two categories: DC Level 1 and DC Level 2. In addition to the power output of 36 kW, the current capacity of DC L1 charging stations also reaches 80 A. The DC L2 power output charger has a current capacity of 200 A and an output power of 90 kW. Most DC power output charging stations are located in shopping malls, government buildings, movie theaters, airports, and gas stations (Mayfield and Ohio, 2012). SAE and IEC recommend the use of DC charger connectors that comply with the SAE/IEC J1772/IEC 62196-3 standard. A significant disadvantage of DC fast charging stations is the high installation cost.