Vehicle-to-grid

Vehicle-to-grid (V2G) describes a system in which plug-in electric vehicles (PEVs) sell demand response services to the grid.

[1][2][3] Vehicle-to-load (V2L) and Vehicle-to-vehicle (V2V) are related, but the AC phase is not synchronised with the grid, so the power is only available to "off-grid" load.

Uni-directional V2G (UV2G) charging is technically simpler than delivering power from an EV battery, which many PEVs are not equipped to do.

[13] Peak load leveling supports regulation services (keeping voltage and frequency stable) and provides spinning reserves (to meet sudden demands for power).

[14] V2G could buffer variable power sources by storing excess energy and providing it to the grid during high-load periods.

Charging stations must integrate software that communicates with the central grid to monitor real-time system demand.

[18][19] California's grid operator, CAISO, defines four levels of Vehicle-Grid Interface (VGI):[20] V1G involves varying the time and rate at which an electric vehicle is charged.

[21] V2G allows vehicles to supply electricity to the grid, with energy paid for by the operator of the utility or transmission system.

[29] V2G requires specialized hardware (such as bidirectional inverters), has significant energy losses and limited round-trip efficiency, and the charge/discharge cycling may shorten battery life.

[30] EVs typically allow fast DC-charging, with the transformer in a charging station connected directly to the vehicle battery.

Coping with this heightened demand presents a significant challenge for both power companies and government agencies.

[41][42] Using V2G software from Nuvve,[43] the bus batteries are aggregated with others in a nearby school district to form a participating resource under the Emergency Load Reduction Program (ELRP),[44] which was initiated in 2021 by the California Public Utilities Commission.

In North America, at least two major school-bus manufacturers—Blue Bird and Lion—are working on proving the benefits of electrification and V2G technology.

Their electrification could help to stabilize the electricity grid, lessen the need for power plants, and reduce gas and particulate pollution and carbon dioxide from exhaust emissions.

Two bidirectional charging stations, connected to a V2G aggregation server managed by Nuvve Corporation, were installed at a parking lot in Aichi Prefecture.

[53] The Edison Project intends to install enough turbines to accommodate 50% of Denmark's total power needs, while using V2G to protect the grid.

During the hours of peak energy use, or when the wind is calm, the power stored in these PEVs will be fed into the grid.

This project was partnered by DTU,[55] Insero, Nuvve, Nissan and Frederiksberg Forsyning (a Danish distribution system operator in Copenhagen).

The partners explored commercial opportunities by systematically testing and demonstrating V2G services across car brands.

[57] In October 2019, a consortium called Vehicle to Grid Britain (V2GB) released a research report on the potential of V2G technologies.

[60] Since 2020, the Australian National University's (ANU) Realising Electric Vehicle-to-grid Services (REVS) team has been studying the reliability and viability of V2G at scale,[61] spinning off the Battery Storage and Grid Integration Project[62] initiative.

In 2022 the first V2G charger became available to purchase in Australia, but delays in rolling them out occurred due to regulatory processes, each State Power Authority needing to certify them as compliant (following Australian government approval).

[70] The two companies implemented their solution in a private household to test the interaction of a photovoltaic (PV) system, battery storage and bidirectional charging.

The house is equipped with three batteries with a combined capacity of 27 kWh, a DC charger and a PV system of 5.6 kWp (kilowatt-peak).

In 2014, Southwest Research Institute (SwRI) developed the first V2G aggregation system qualified by the Electric Reliability Council of Texas (ERCOT).

[71] The system was originally developed as part of the Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS) Phase II program, led by Burns and McDonnell Engineering Company, Inc.[72] In November 2012, SwRI was awarded a $7 million contract from the U.S. Army Corps of Engineers to demonstrate V2G.

[19][77] An operational implementation in Europe was conducted through the German government-funded MeRegioMobil project with Opel as vehicle partner and utility EnBW providing grid expertise.

[49][80] Lawrence Berkeley National Laboratory developed V2G-Sim, a simulation platform used to model spatial and temporal driving and charging behavior of individual PEVs on the grid.

[86] JB Straubel, then chief technology officer of Tesla Inc, discounted V2G, claiming that battery wear outweighs economic benefit.

[90] A 2015 study[91] found that economic analyses favorable to V2G failed to include many of the less obvious costs associated with its implementation.