Vehicle to Grid

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24 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Vehicle to Grid

Electric Vehicles as Grid Storage

Andrew Levitt

Project Manager for Vehicle
Grid project
sponsored by NRG Energy and University of

Transition to Carbon
free Power

Those most concerned with climate change
envision a world with very limited carbon

This would entail a radical increase in use of
variable electricity generation from wind and

Grid storage

Today, fuel storage and dispatch accomodates
variability and unpredictability in electric load

Day 1

Day 3

Day 5

Day 7

Electric load (GWh)

99.9% renewables on Mid
Atlantic grid

Day 1

Day 3

Day 5

Day 7


Budischaka, et al, 2013. J. Power Sources.

A hard week of all

Day 1

Day 3

Day 5

Day 7


Budischaka, et al, 2013. J. Power Sources.

Electric energy storage allows
avoidance of fuel storage

Electric vehicles

Electric Vehicles. Consider:

There are about 200 million light vehicles in the United

In low
carbon world, most would (debatably) be electric

An electric vehicle is necessarily a substantial
investment in:

Energy storage

100 kilowatts of two
way power conversion from
battery to electricity

Cars are unused for about 23 hours per day

1. 190 million. US US Bureau of Transportation, 2013.

2. Shoup, 2005. “The High Cost of Free Parking”.

If half of US cars were electric:

Electric vehicle power capacity

100 million x 100 kW = 10,000 gigawatts

~10x the peak capacity of the US grid

Electric vehicle storage capacity

100 million x 40 kWh = 4,000 gigawatt

Enough to run the US grid (at average load of
500GW) for 8 hours

Of course cars need to drive…

Maximize Value

Bidirectional power flow: enable multiple
electric services, and allow continuous

Use motor drive electronics for charging/

negative cost, high power

High power (e.g. push to J1772 limit of 19 kW)

User conveinence of high charge rate

Charge rate

Miles added per hour*

J1772 “level 1”

4 kW


J1772 “Full spec”

19 kW


IEC 62196 (3 ph)

52 kW†



50 kW


*4 mi/kWh. † IEC62196 in EU=44kW, in US=52kW

Photo credit: Tim Shaffer, NY Times

Costs of using electric vehicle as grid

Control electronics on car and charging station
(currently ~$400 each)

Battery wear

Administrative and scheduling time

Cost per kilowatt: $27/kW

Cost per kilowatt
hour: $13/kWh

Compare to purpose
built storage…

Battery wear

Depending on chemistry, decrease of battery
life may be expected when exercised under
certain conditions:

Very high or low state of charge

Very high sustained charge or discharge current

More full
charge cycles

Determining what and how much impact V2G
has on batteries is a goal of current research.

Vehicles comprise a mostly
idle capital
investment in enormous power
production and energy storage.

It is low cost to harness this resource for
connected energy storage.

Grid services

V2G value

Grid balancing services (grid operators)

Defer distribution investment (utilities)

Arbitrage (energy markets)

Limit demand charge (commercial consumer)

Firming and leveling renewables (wind
operator or grid operator)


Grid has to balance supply and demand at each moment

Scheduling of generation and load accomodates almost
all of this.

Unpredictable, instantaneous inaccuracies are
compensated by fast balancing reserves (below).

Two hours of response by balancing reserves in PJM on June 5, 2013

One Hour

V2G in operations

With this fast balancing
service, battery state
charge stays
between 50% and 75%

It does not drain the

A trip scheduler triggers
charging of car to full
capacity when needed.

Balancing reserves market

2013 average price of
3.0¢ per kilowatt

Corresponding revenue
is $320 per month with
18kW charging at home
and work, accounting
for charge time for

Fast grid balancing provides
several hundred dollars in
gross revenue per car per

Fast grid balancing does not
drain the battery of an
electric car.

V2G Project

Photo credit: Tim Shaffer, NY Times

Project Collaborators


Preliminary V2G system developed by University
of Delaware in 2007 and launched with 3 vehicles
in 2008

NRG Energy bought a stake in the technology in

Milbank Manufacturing licensed the V2G
charging station in early 2012.

BMW finalized donation of a fleet of purpose
built all
electric MINI E’s in early 2012.

Also engaging several major japanese carmakers
and domestic electric truck manufacturers.


First ever payment by a grid to a
car was for services on February
27 of this year

Operating with a stationary test
bed plus 3 fleet cars since

Generating up to $5 per car per
day providing balancing reserves

Continuing to refine technology
for release to small number of
test drivers. Still open for fleet

developed, V2G
Milbank charging station soon to
be commercially released

Currently looking to expand to
other grid operator territories

Photo credit: Tim Shaffer, NY Times


Andrew Levitt