Vehicle-to-Grid (V2G) system is an effective approach to expand the electrification of the transportation sector. This electrification has significantly emerged at light-duty vehicle fleets including plug-in electric vehicles (PEV), plug-in hybrid electric vehicles (PHEV), and hydrogen fuel cell electric vehicles (FCEV) [1,2]. V2G systems can be categorized into two general classes: unidirectional and bidirectional.
The air pollution and CO2 emissions owing to burning fossil fuels lead global communities to find non-fossil fuel-based solutions. They want to bring back more resilience and sustainability to the power and transportation sector. Burning dirty fossil fuels by internal combustion engine vehicles (ICEV) and power plants have resulted in increasing global climate change concern, energy price as well as reducing energy security. The electrification of the vehicle fleet and making greener power generation have emerged as feasible solutions to the transportation and power sectors respectively to address the aforementioned concerns.
A Unidirectional V2G system is a one-sided system that provides electricity for electric vehicles (EVs). EVs are only energy consumers in this type of V2G system. The grid is considered as the main source of supplying electricity for EVs. However, in a bidirectional V2G system, both the grid and EV are thought as power suppliers. In this regard, EVs are simultaneously consumers and suppliers of energy. In other words, EVs have gained a sense of prosumers in these systems. The bidirectional V2G system, when the substantial amount of EVs with bidirectional plug-in option aggregated, has several advantages over unidirectional one including
- Providing peak shaving for the gird
- Making grid stability improvement
- Being a dynamic backup power supply to reduce blackouts.
EVs can work as an ancillary system in which peak shaving occurs during predictable highest power demand hours . On the other hand, a steep increase in the integration of renewable energy sources (RES) into the power system has raised the unpredictability of power generation. It has resulted from the intermittent nature of renewables including solar and wind power . The high penetration of RES technologies seriously affects energy security and grid stability.
One of the possible solutions to address the grid stability and energy security issues is adding energy storage systems (ESS) to the grid [4-6]. EVs with bidirectional plug-in options can be seen as dynamic backup power suppliers or even called energy storage systems on wheels . Bidirectional V2G systems would also play a key role in emergency conditions when blackouts occurred due to the harsh weather conditions.
V2G systems can be divided into subsystems such as vehicle to home (V2H), vehicle to building (V2B), and generally vehicle to everything (V2X) . Therefore, by implementing the infrastructure of the internet of things (IoT) in the grid, bidirectional V2G systems lead to synergistic effects including providing a room for higher RES technologies penetration, reducing CO2 emissions, and also reducing electricity price because it does not need extra infrastructure to add ESS. It is often called the energy sustainability trilemma addressing simultaneously cost-effectiveness, reduction of CO2 emissions, and providing resilience for the grid . Then, V2G systems can meet the requirement of the energy trilemma.
The global rise in exploiting more renewable energy sources such as solar, wind, and hydropower is one of the green initiatives that has been done in this direction [4,9]. While the electrification of the transportation sector is lagging behind. But implementing V2G systems in addition to the growing tendency of the public to EVs could accelerate the green shift as well.
Author: Amir Hayati Soloot
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 Vehicle-to-Grid (V2G):Everything You Need to Know
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