Nissan Leaf the fully electric adventure enterprise that began in 2010. Today, however, the second generation of these electric cars, over...
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| Nissan Leaf the fully electric adventure enterprise that began in 2010. Today, however, the second generation of these electric cars, over 300,000 vehicles are sold. |
Vehicle-to-grid (V2G) is a system to plug-in electric vehicles, such as battery electric vehicles (BEV), plug-in hybrids (PHEV) or hydrogen fuel cell electric vehicles (FCEV), communicate with the power grid. V2G storage capabilities can enable Electrical Vehicle (EV) to store and discharge electricity generated from renewable energy sources such as solar and wind.
V2G can be used with gridable vehicles, that is, plug-in electric vehicles (BEV and PHEV), with grid capacity. Since at any given time 95 percent of cars are parked, the batteries in electric vehicles could be used to let electricity flow from the car to the electric distribution network and back.
Applications
Peak load leveling: The concept allows V2G vehicles to provide power to help balance loads by "valley filling" (charging at night when demand is low) and "peak shaving" (sending power back to the grid when demand is high, see duck curve). Peak load leveling can enable new ways for utilities to provide regulation services (keeping voltage and frequency stable) and provide spinning reserves (meet sudden demands for power).
It has been proposed that public utilities would not have to build as many natural gas or coal-fired power plants to meet peak demand or as an insurance policy against power outages. Since demand can be measured locally by a simple frequency measurement, dynamic load leveling can be provided as needed. Carbitrage, a portmanteau of 'car' and 'arbitrage', is sometimes used to refer to the minimum price of electricity at which a vehicle would discharge its battery.
Backup power
Modern electric vehicles can generally store in their batteries more than an average home's daily energy demand. Even without a PHEV's gas generation capabilities such a vehicle could be used for emergency power for several days (for example, lighting, home appliances, etc.). This would be an example of Vehicle-to-home transmission (V2H). As such they may be seen as a complementary technology for intermittent renewable power resources such as wind or solar electric. Hydrogen fuel cell vehicles (FCV) with tanks containing up to 5.6 kg of hydrogen can deliver more than 90 kWh of electricity.
Unidirectional V2G or V1G
Many of the grid-scale benefits of V2G can be accomplished with unidirectional V2G, also known as V1G or "smart charging". The California Independent System Operator (CAISO) defines V1G as "unidirectional managed charging services" and defines the four levels of Vehicle-Grid Interface (VGI), which encompasses all of the ways that EVs can provide grid services, as follows:
- Unidirectional power flow (V1G) with one resource and unified actors
- V1G with aggregated resources V
- 1G with fragmented actor objectives Bidirectional power flow (V2G)
V1G involves varying the time or rate at which an electric vehicle is charged in order to provide ancillary services to the grid, while V2G also includes reverse power flow. V1G includes applications such as timing vehicles to charge in the middle of the day to absorb excess solar generation, or varying the charge rate of electric vehicles to provide frequency response services or load balancing services.
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V2G technology connecting Nissan electrical vehicle to Grid (V2G) Charging. Image: Fleetcarma.com
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Efficiency
Most modern battery electric vehicles use lithium-ion cells that can achieve round-trip efficiency greater than 90%. The efficiency of the battery depends on factors like charge rate, charge state, battery state of health, and temperature.The majority of losses, however, are in system components other than the battery. Power electronics, such as inverters, typically dominate overall losses. A study found overall round-trip efficiency for the V2G system in the range of 53% to 62%'. Another study reports an efficiency of about 70%. The overall efficiency, however, depends on several factors and can vary widely.
A study conducted in 2012 by the Idaho National Laboratory revealed the following estimations and future plans for V2G in various countries. It is important to note that this is difficult to quantify because the technology is still in its nascent stage, and is therefore difficult to reliably predict the adoption of the technology around the world. The following list is not intended to be exhaustive, but rather to give an idea of the scope of development and progress in these areas around the world.
United States
PJM Interconnection has envisioned using US Postal Service trucks, school buses and garbage trucks that remain unused overnight for grid connection. This could generate millions of dollars because of these companies aid in storing and stabilizing some of the national grid's energy. The United States was projected to have one million electric vehicles on the road between 2015 and 2019. Studies indicate that 160 new power plants will need to be built by 2020 to compensate for electric vehicles if integration with the grid does not move forward.
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| EverCharge Project. Image: www.evercharge.net |
Japan
In order to meet the 2030 target of 10 percent of Japan's energy being generated by renewable resources, a cost of $71.1 billion will be required for the upgrades of existing grid infrastructure. The Japanese charging infrastructure market is projected to grow from $118.6 million to $1.2 billion between 2015 and 2020. Starting in 2012, Nissan plans to bring to market a kit compatible with the LEAF EV that will be able to provide power back into a Japanese home. Currently, there is a prototype being tested in Japan. Average Japanese homes use 10 to 12 KWh/day, and with the LEAF's 24 KWh battery capacity, this kit could potentially provide up to two days of power. Production in additional markets will follow upon Nissan's ability to properly complete adaptations.
In November 2018 in Toyota City, Aichi Prefecture, Toyota Tsusho Corporation and Chubu Electric Power Co., Inc initiated charging and discharging demonstrations with storage batteries of electric vehicles and plug-in hybrid vehicles using V2G technology. The demonstration examines how to excel the ability of V2G systems to balance demand and supply of electricity is and what impacts V2G has on the power grid. In addition to ordinary usage of EVs/PHVs such as by transportation, the group is producing new values of EVs/PHVs by providing V2G services even when EVs/PHVs are parked. Two bi-directional charging stations, connected to a V2G aggregation server managed by Nuvve Corporation, have been installed at a parking lot in Toyota City, Aichi Prefecture to conduct the demonstration test. The group aims to assess the capacity of EVs/PHVs to balance out demand and supply of electrical power by charging EVs/PHVs and supplying electrical power to the grid from EVs/PHVs.
Denmark
Denmark currently[when?] is a world leader in wind power generation. Initially, Denmark's goal is to replace 10% of all vehicles with PEVs, with an ultimate goal of a complete replacement to follow. The Edison Project implements a new set of goals that will allow enough turbines to be built to accommodate 50% of total power while using V2G to prevent negative impacts to the grid. Because of the unpredictability of wind, the Edison Project plans to use PEVs while they are plugged into the grid to store additional wind energy that the grid cannot handle.
Then, during peak energy use hours, or when the wind is calm, the power stored in these PEVs will be fed back into the grid. To aid in the acceptance of EVs, policies have been enforced that create a tax differential between zero-emission cars and traditional automobiles. The Danish PEV market value is expected to grow from $50 to $380 million between 2015 and 2020. PEV developmental progress and advancements pertaining to the use of renewable energy resources will make Denmark a market leader with respect to V2G innovation (ZigBee 2010).
Following the Edison Project, the Nikola project was started which focused on demonstrating the V2G technology in a lab setting, located at the Risø Campus (DTU). DTU is a partner along with Nuvve and Nissan. The Nikola project completed in 2016, laying the groundwork for Parker, which uses a fleet of EVs to demonstrate the technology in a real-life setting. This project is partnered by DTU, Insero, Nuvve, Nissan and Frederiksberg Forsyning (Danish DSO in Copenhagen).
Besides demonstrating the technology the project also aims to clear the path for V2G-integration with other OEMs as well as calculating the business case for several types of V2G, such as Adaptive charging, overload protection, peak shaving, emergency backup and frequency balancing. In the project the partners explored the most viable commercial opportunities by systematically testing and demonstrating V2G services across car brands. Here, economic and regulatory barriers were identified as well as the economic and technical impacts of the applications on the power system and markets. The project started in August 2016 and ended in September 2018.
United Kingdom
The V2G market in the UK will be stimulated by aggressive smart grid and PEV rollouts. Starting in January 2011, programs and strategies to assist in PEV have been implemented. The UK has begun devising strategies to increase the speed of adoption of EVs. This includes providing universal high-speed internet for use with smart grid meters, because most V2G-capable PEVs will not coordinate with the larger grid without it. The "Electric Delivery Plan for London" states that by 2015, there will be 500 on-road charging stations; 2,000 stations off-road in car parks; and 22,000 privately owned stations installed. Local grid substations will need to be upgraded for drivers who cannot park on their own property. By 2020 in the UK, every residential home will have been offered a smart meter, and about 1.7 million PEVs should be on the road. The UK's electric vehicle market value is projected to grow from $0.1 to $1.3 billion between 2015 and 2020 (ZigBee 2010).
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| Nissan and its partners have welcomed the announcement by Department for Business, Energy and Industrial Strategy minister Richard Harrington to award £9.8m for a Vehicle-to-Grid demonstrator project. Image: Newcastle University / UK |
EDF Energy is the largest electricity supplier to UK businesses and its partnership with Nuvve could see the largest deployment of V2G chargers so far in this country. In fall 2019, a consortium called Vehicle to Grid Britain (V2GB) released a research report on the potential of V2G technologies.