Willett Kempton
College of Marine and Earth Studies University of Delaware
Vehicle to Grid Power
Workshop at IEEE Conference
Plug-In Hybrids: Accelerating Progress
Washington, DC, September 19, 2007
Four Big Problems
Global climate change. Evidence in the past two years suggest far more risk than before.
Peak oil production; demand from China and India soaring; $200B/year in Middle East wars.
US economy extraordinarily vulnerable to external supply and distant politics.
Renewable energy plentiful at competitive prices, limited by intermittent supply.
Multiple Solutions with
Plug-in cars + V2G
It may be easier to solve multiple problems at once than one at a time.
Plug-in cars -- batteries are now here Wind power: plentiful but intermittent Energy storage in gas tank -> in battery
Wind Resources of
US Mid-Atlantic
m
Excl GW
0-20 .46
60
20-50 .40
117
50-100 .10
153
Total
330
End-use
GW
avgElec. load
73
Lt. veh
35
Rethinking the basics
There will be lots of no-CO2 electricity at per kWh
(energy) prices lower than today, especially off-peak Electricity storage or backup (e.g. ancillary services markets) will be in much greater demand than today (but hopefully also cheaper per MW-h)
How can we use lots of cheap electricity at times dictated by the grid operator (ISO or TSO)?
From an electrical standpoint, ideal car would have: battery 20-30 kWh, plug 15+ kW (240 V, 80 A).
Two cars meet this and are in (limited) production: AC Propulsion eBox, an “urban utility vehicle”, also a sedan based on Yaris -- now
hand-assembled (has V2G)
Tesla Roadster, being produced by Lotus for Tesla (working on G2V or “intelligent charging”)
Hybrids can be used for V2G but are generally lower power (1.5 kW), different business model
Tesla Roadster
An Unexpected Synergy
Intermittent renewable energy and electricity as carrier for vehicles No new transportation or fuel
infrastructure needed
Smart interaction between vehicle fleet, grid and intermittent renewables
Very large, low-cost storage for renewables Vehicle to Grid power (“V2G”) as a bridging technology.
Vehicle to Grid
V2G Basic Math
Average car driven 1 hour/day --> time parked is 23 hours/day
Daily average travel: 32 miles
Practical power draw from car: 10 - 20 kW US power generation=811 GW; load=417 GW US 191 million cars x 15 kW = 2,865 GW
Calculating V2G power
V2G power is the lowest of 3 factors:
Wiring & plug at parking location, prepare for mass markets by assuming residential, say, 240VAC @ 80A ≈ 20 kW
Internal Power Electronics to motor (typical 100 kW)
Stored energy ÷ time
Note: our equations are general to all:
How Much Power?
Denmark
UK USA
Avg. Electric Load (GW) 3.6 40 417 Light vehicles (106) 1.9 28.5 191 Vehicle GW(if electric drive
How Much Power?
Denmark
UK USA
Avg. Electric Load (GW) 3.6 40 417 Light vehicles (106) 1.9 28.5 191 Vehicle GW(if electric drive
@ 15 kW each) 29 427 2,865
Effect of EVs with V2G on Grid
Infrastructure Requirements
• 50% of cars as EVs increase electric load ? 100 Million cars
x 15,000 Miles per year / 4.8 Miles per kWh = 312 Billion kWh per year at off-peak times = 7 % of 2020 total national load
• With V2G, these EVs also provide a huge power resource: 100 M cars * 15 kW * 0 .5 avail. = 750 GW of DG
> 70% of 2020 national electric power capacity!
Conclusion: Even 50% of cars as EV, IF they have V2G, probably REDUCE grid infrastructure requirements
(Using “back of the envelope ” method from W. Short, NREL, 2005)
Transition Strategy
Business model demonstration: sets of
100+ cars
Reassembly vs. OEM
Start simple: Battery now, e-hybrid later
Now building the “Mid-Atlantic
A/S Regulation: Fleet
operator as IPP
100 vehicles, parked 18h/d (16 h * 5 days + 24 h * 2 days), 80% available, each 20 kW A/S
regulation services at $38/MW-h.
Single connection point, single meter, 2 MW peak “generator” --> higher ISO comfort
Revenue: 100*18h*365d*.8*.02MW*$38= $400,000/year revenue from fleet
Transition Strategy
Small fleets: 100 car V2G fleet = 1 MW; demonstrate V2G business models
Production in several regions, develop technology, drive down component costs
Develop standards for V2G (e.g. response time, metering, at least 10 kW/car, drawdown limits, etc)
THEN we need the OEMs, low-cost production at > 50,000 cars/year
But, don’t we need to
wait for the big OEMs?
OEMs won’t start V2G
change
Expertise in combustion, mechanical
engineering, low-cost mass production; engine as the primary value added (other components are commodity items)
No expertise or IP in electrochemistry, power electronics, power markets
Consumer’s performance space inviolable Next step needed is “power-plant size”
demonstration, need 100 - 500 vehicles; OEMs cannot do this efficiently or cheaply
BEV and PHEV Logic
Non-fossil carriers essential to the future
Hydrogen unlikely, especially in the near term, thus electricity primary carrier
CO2 displacement by electricity large only if non-CO2 generation (e.g. hydro or wind)
Electricity as carrier goes directly to V2G logic...
V2G Logic
Cars: A power resource too large to ignore
V2G makes electric power capacity cheap, but electric energy is still expensive
Today, market value for grid management Future, enable very large renewable energy
Optimize design for both transport and electric system -- OEMs will not do this
Vision
One-half vehicle fleet is electric drive: battery plus plug-in hybrid
One-half of electric energy from wind, eventually other renewables
Climate change is greatly slowed down; US can survive (a while) without foreign oil
CO2-free electricity, high-penetration intermittent renewables, and CO2-free transportation: an
