# Review of Renewable Energy-Based Charging Infrastructure for Electric Vehicles
## 3 Appropriate Renewable Energy Sources  
Wind and solar energies are considered to be reliable substitution sources of conventional energy sources because of their economic and environmental benefits [11; 43; 44; 45]. However, one of the disadvantages of these renewable sources is their inconsistency in offering energy. They do not generate power all the time, and they are intermittent. However, a few suggestions for solar-based charging facilities are discussed in [35; 36; 46]. The researchers proposed charging infrastructure dedicated to the range of low to medium EVs. In [47], the researchers suggested charging EVs from solar energy using the DC link voltage sensing. The aim is to lower the burden on the distribution transformer. However, solar energy limitation to charge wide-range EVs will lower the chances of implementing more solar-based charging stations.  
Research work on the control and optimization of wind turbines (WT) has demonstrated that wind energy is an appropriate choice for EV charging infrastructure. In [44], the researchers discussed the advantages of implementing charging stations based on large-scale turbines and found that EVs could be a critical factor for enabling the high penetration of wind energy. Considering the challenges of traditional scheduling and dispatching mechanisms, researchers in [48] developed a model of utilizing the flexibility of charging EVs to optimally compensate for wind energy fluctuations. They found that shifting EVs' charging to times with high wind availability achieved cost savings. In another study [49], the possibility of using wind energy as a direct source for power EV charging stations were investigated. The researchers implemented an interval-based method corresponding to the time slot taken for EV charging for wind energy conversion and evaluated using various constraints and parameters, including the averaging time interval for wind speed, different turbine manufacturers, and regular high-resolution wind speed datasets. The analysis indicated that the use of direct wind to EV provides enough constant power for large-scale charging stations.  
The researchers in [50] developed optimal charging infrastructure using wind turbines for different charging modes concerning the optimal charging power. The infrastructure is connected to the grid and has an energy storage system. The rated power was optimized on 52, 84, and 116 kW for slow, intermediate, and quick-speed charging, respectively. On the other hand, the study [50] developed a power management model to enhance wind energy reliability.  
However, we can conclude that solar and wind energies are appropriate sources for EV charging infrastructure. A charging facility can be either hybrid (solar and wind) or non-hybrid with the use of suitable storage capacity to support the charging process during the fluctuation of sources. The power generator's sizing depends mainly on the type of charging (fast, medium, or slow). Nonetheless, the use of battery storage has a negative impact on the environment. The study results of [51] indicate that global electronic mobility demand will boost the production of batteries by 2030 to around 1725 GWh, and nickel will be the dominant raw material in the lithium-ion battery. Currently, batteries' demand represents 4% of the annual global nickel production, and the gradual scenario is that nickel demand would rise to 34% of present mining production in 2030. Even if nickel is an important component for plants, like every metal and chemical, the quality of the environment for flora and fauna may be negatively affected by its excessive amounts. As a result, nickel is strictly controlled and subjected to rigorous evaluations under a variety of legislative frameworks [52].