Vehicle-to-grid (V2G) describes a system in which power can be sold to the electrical power grid by an electric-drive motor vehicle that is connected to the grid when it is not in use for transportation. cite book
first =Cutler J.
coauthors =Morris, Christopher
title =Dictionary of Energy
isbn =0080445780 Page 473. ] Alternatively, when the car batteries need to be fully charged, the flow can be reversed and electricity can be drawn from the electrical power grid to charge the battery.
Vehicle-to-grid can be used with such "gridable" vehicles, this is, "
pluginable" vehicles as Battery Electric Vehicles(BEV) or Plug-in hybridelectric vehicles (PHEV), with grid capacity. Since most vehicles are parked an average of 95 percent of the time, their batteries could be used to let electricity flow from the car to the power lines and back, with a value to the utilities of up to $4,000 per year per car. Since power companies only buy power in blocks of 1 MW, at least 20,000 vehicles need to be connected to the grid.cite web
year = 2007 | month = December 9| title = Car Prototype Generates Electricity, And Cash
work = Science Daily
Many various V2G projects are going on throughout the USA. Notably, at the University of Delaware, a V2G team headed by Dr. Willett Kempton has been conducting on-going research. Their goals are to educate about the environmental and economic benefits of V2G and enhance the product market.cite journal
year = 2007
month = September 2
title =Power to the People: Run Your House on a Prius
New York Times
url = http://www.nytimes.com/2007/09/02/automobiles/02POWER.html] cite web
year = 2001
month = June
title = V2G : Vehicle to Grid Power
url = http://www.udel.edu/V2G]
The company AC Propulsion Inc. coined the term V2G for vehicle-to-grid. cite book
first = Ali
year = 2005
title =Handbook of Automotive Power Electronics and Motor Drives - Page 34
id =Page 34 ]
V2G is a version of
Battery-to-gridpower applied to vehicles. There are three different versions of the vehicle-to-grid concept:
*A hybrid or
Fuel cell vehicle, which generates power from storable fuel, uses its generator to produce power for a utility at peak electricity usage times. Here the vehicles serve as a distributed generationsystem, producing power from conventional fossil fuels.
*A battery-powered or
hybrid vehiclewhich uses its excess rechargeable batterycapacity to provide power to the electric grid during peak loadtimes. These vehicles can then be recharged during off-peakhours at cheaper rates while helping to absorb excess night time generation. Here the vehicles serve as a distributed battery storage system to bufferpower.
solar vehiclewhich uses its excess charging capacity to provide power to the electric grid when the battery is fully charged. Here the vehicle effectively becomes a small renewable energypower station. Such systems have been in use since the 1990s and are routinely used in the case of large vehicles, especially solar-powered boats.
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). It can enable utilities new ways to provide
regulation services (keeping voltage and frequency stable) and provide spinning reserves (meet sudden demands for power). In future development, it has been proposed that such use of electric vehicles could buffer renewable power sources such as wind power, for example, by storing excess energy produced during windy periods and providing it back to the grid during high load periods, thus effectively stabilizing the unreliable nature of wind power. Some see this application of vehicle-to-grid technology as a renewable energy approach that can penetrate the baseline electric market.
It has been proposed that
public utilitieswould not have to build as many natural gas or coal-fired power plants to meet peak demandor as an insurance policy against blackoutsWoody, Todd. [http://blogs.business2.com/greenwombat/2007/06/photo_green_wom.html "PG&E's Battery Power Plans Could Jump Start Electric Car Market."] (Blog). "Green Wombat", 2007- 06-12. Retrieved on 2007- 08-19.] Since demand can be measured locally by a simple frequency measurement, dynamic load leveling can be provided as needed. [ [http://www.freepatentsonline.com/4317049.html Frequency adaptive, power-energy re-scheduler] (Patent)]
Backup power solutions
V2G could also be used as a buffer during
power outages. However, at the present time many electric vehicle conversionowners, whose battery of choice is still lead acid with limited cycle lives and capacity, would prefer to use them to power their cars rather than load-balance the electricity grid.
As the "New York Times" explains:
Future battery developments cite web
year =2005 | month =March 29
title =Toshiba's New Rechargeable Lithium-Ion Battery Recharges in Only One Minute
work =Toshiba Corporation | url = http://www.toshiba.co.jp/about/press/2005_03/pr2901.htm
accessdate=2007-12-05 (Press release) ] may change the economic equation, making it advantageous to use newer high capacity and longer-lived batteries in BEV/PHEVs and in grid load balancing and as a large energy cache for renewable grid resources. Even if cycled daily, such batteries would only require replacement/recycling every 55 years or so. Since BEVs can have up to 50 kWh worth of battery storage they represent somewhat more than the average homes daily energy demand. Even without a PHEV's gas generation capabilities such a vehicle could be utilized for emergency power for several days (V2H or Vehicle-to-home). As such they may be seen as a complementary technology for intermittent renewable power resources such as wind or solar electric.Fact|date=December 2007
These utilities currently have V2G technology trials:
PG&E, USA, converting a number of company-owned Toyota Prius to be V2G PHEVs at Google's campus
Xcel Energy, USA, converting six Ford Escape Hybrids to PHEVs with V2G
There is some skepticism among experts about the feasibility of V2G. As the New York Times states:
Environmental Defenserepresentative stated: "It’s hard to take seriously the promises made for plug-in hybrids with 30-mile all-electric range or any serious V2G application any time soon. It’s still in the science project stage."
The Vehicle-to-grid potential of Honda’s full hybrid vehicles is unexplored, but Honda is doubtful of using them to power homes. "We would not like to see stresses on the battery pack caused by putting it through cycles it wasn’t designed for," said a Honda spokesman. "Instead, they should buy a Honda generator that was made for that purpose."
Not all skepticism is warranted.
Federal Energy Regulatory Commissioner Jon Wellinghoffpoints out that it is a myth that vehicle to grid necessarily decreases the life of the battery. When V2G is used to fill valleys of demand, it stabilizes the grid by absorbing surges in capacity. This can be done "without affecting the charge whatsoever." ["Plug-in Electric Vehicles 2008: What Role for Washington" Conference transcript, page 347, hosted by Brookings Institution and Google.org on 11-12 June 2008 [http://www.brookings.edu/~/media/Files/events/2008/0611_plugin_vehicles/0611_plugin_vehicle.pdf] ]
Energy demand management
Grid energy storage
Grid-tied electrical system
Peaking power plant
Small is Profitable
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last = Diehl
title = Study suggests electric cars could pay their owners back
journal = Green Mountain College
url = http://www.greenmtn.edu/news/V2G.asp
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first = Willett
month =6 June
title = Automobiles: Designing the 21st century fleet
journal = Seattle V2G Technical Symposium, University of Delaware
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url = http://blogs.business2.com/greenwombat/2007/06/photo_green_wom.html
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coauthors = Sexton, Chelsea; Brilliant, Larry
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journal = UQM Technologies, Inc.
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title = Hybrid Center
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accessdate=2007-10-05 Company promoting v2G technology.
month =October 22
title =World's First V2G Demo
work =The California Cars Initiative
title = gridable-hybrids
title = priusplus
title = Calcars
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