uk electric vehicles programme: the challenges of v2g
TRANSCRIPT
UK Electric Vehicles Programme:The challenges of V2G (Vehicle to Grid) operation
Professor Roger Kemp FREng
Lancaster University
Two reports
Electric Vehicles:charged with potential
Commitment to an 80% reduction in CO2 emissions by 2050
Energy flow chart for 2008
LGH = low-grade heat, HGH = high-grade heat
Initial conclusions of RAEng studies
To meet the obligations of the Climate Change Act, we cannot continue to use gas for space heating and petrol/diesel for transport
Most energy for transport will have to be provided by renewables/nuclear power(via electricity or hydrogen?)
At least half of energy for space heating will have to be provided by renewables or nuclear power (via electricity and heat pumps)
What proportion of cars must be electric?
To achieve a worthwhile saving of CO2 the majority of car travel will have to be powered by electricity. The Climate Change Committee aims that 60% of new cars should be electric by 2030
The challenge is to move EVs from commuter and second cars to family and company cars
High-capacity energy storage
Photo: Tesla Roadster 2008
Battery 53 kWh, 88% charge/discharge efficiency to charge in 8 hours requires 7.5 kW (average)
Electric vehicle trials
Public charging points
A future scheme should:
provide at least 5 kW
include credit/smart card billing
encourage overnight charging
respect privacy/security
be self-funding
adopt international standards
Photo: Plugged-in Places
Daily demand on the electricity grid
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10
20
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0 48 96 144 192 240 288 336
Feb-10
Jul-09
M T W T F S S
Data for first wholeweek in month
Lo
ad G
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The UK does not have large hydro resources
Three Gorges dam Loch Lyon dam
Renewable energy
Economics of renewable energy depend on electricity demand being there when the wind blows or the sun is shining
Daily demand on the grid
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10
20
30
40
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0 48 96 144 192 240 288 336
Feb-10
Jul-09
M T W T F S S
Lo
ad G
W
Above this level of supplyrenewables + nuclear could not be guaranteeda market
Data for first wholeweek in month
Challenges for the 2050 energy supply
Loads
Existing load varying between 20 GW and 60 GW
New loads from electric heating – much greater in winter and varying by time of day
Up to 30 million electric vehicles – time of charging can be adjusted
Generation
Renewables – mainly depending on wind, tides or sun
Nuclear – designed for base load generation
Energy storage in EV batteries (in 2050)
Energy storage/car 20 kWh
Number of electric cars (2050) 30 million
Fleet energy storage 600 GWh
2050 max demand 100 GW
Can any of this capacity be used to support the grid?
Challenges for a “smart grid”
Battery 90% fullNext use 12 h time
Battery 10% fullNext use 5 h time
Battery 50% fullNext use ? h time
Battery 60% fullNext use 1 h time
Control objectives:
Arrange all vehicles to be charged for when next needed
Maximise use of low-carbon electricity
Avoid overloading distribution network
V2G (vehicle-to-grid) energy flows
Normal charging:All vehicles charged from grid
V2G:Vehicles with “spare” capacity regenerateenergy back into the grid
NB: This arrangement results in a source of energy in the local network thatis controlled from elsewhere – what are the implications on LV protection?
Strategic objectives of EV battery charging
Manage EV battery charging to maximise use of low-carbon energy
Implement load shedding of EV charging to avoid “brown-outs”
Limit charging loads in local area to prevent overload of distribution network
Manage V2G regeneration to reduce load peaks
