From the last lecture: U.S. total energy consumption:U.S. transport energy consumption: Product of...
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From the last lecture: U.S. total energy consumption:U.S. transport energy consumption: Product of two numbers = ~ 20% of total U.S. energy consumption
From the last lecture: U.S. total energy consumption:U.S.
transport energy consumption: Product of two numbers = ~ 20% of
total U.S. energy consumption. Due to: Non-sustainable,
fossil-fuel-driven, greenhouse-gas-producing, cars and pickups
trucks, driven by individual Americans (Perhaps more if the E.I.A.
classified our larger pickups and massive vans as "Trucks")
Transportation = 27% = 27% LightVehicle = 59.7% Electrification of
Transportation
Slide 2
So today's focus will be on new technologies that might: Lessen
the impact of cars ALONE OR Lessen the impact of our energy system
by integrating cars INTO it Why consider only cars? Well, look back
at what we learned in earlier lectures: Trains: Small impact +
Japan & Europe figured out solutions half a century ago We just
need to wake up and match their 20 th century standard! Ships:
Small impact + long distances demand a LOT of fuel energy
Airplanes: Significant impact + long distances demand a lot of
LIGHT fuel energy An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 3
So other vehicles either have minor impact OR depend critically
on: Energy per mass of fuel or energy per volume of fuel Data on
energy per mass of fuel from earlier lecture: Conventional Battery
= 0.001 x Gasoline's energy density Conventional Battery = 0.001 x
Gasoline's energy density PC Battery = 0.01 x Gasoline's energy
density TNT (0.65 Cal/gm) = 1/15 x Gasoline's energy density Butyl
alcohol= 0.9 x Gasoline's energy density Kerosene / JP-4 / Jet
Fuel= 0.93 x Gasoline's energy density Gas / Diesel= 1 x Gasoline's
energy density Liquid Natural Gas = 1.3 x Gasoline's energy density
Hydrogen = 2.6 x Gasoline's energy density Data mostly from from
Richard A. Muller's book "Physics for Future Presidents"
Slide 4
Fuel densitys impact upon other forms of transportation:
TRAINS: None - Solution for trains is to not carry around fuel
Because, as enabled by limited number of fixed routes, You can pick
it up as you go from either 3 rd rail or overhead lines FLIGHT:
Energy per mass effectively precludes its battery-based
electrification Solar electric planes are interesting but
impractical Mass of storage containers likely also precludes H 2
power http://en.wikipedia.org/wiki/Railway_electrification_system
http://en.wikipedia.org/wiki/Electric_aircraft
Slide 5
And as for shipping: Long routes mean that onboard fuel must
store huge quantity of energy In 1950s and 1960s a nuclear powered
merchant ship was tested: N.S. Savannah Entering San Francisco Bay
in 1962: (She was beautiful I toured her a day or two later) But
outside of cost be damned applications Such as aircraft carriers
and ice-breakers (Where reactor mass can be an advantage) Nuclear
powered ships never became practical Nor was public exactly
delighted with the idea of mobile sinkable reactors Other clean
alternative? Hydrogen, but wed need vastly cheaper sources
http://en.wikipedia.org/wiki/NS_Savannah
Slide 6
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm So in terms
of impact + critical need for innovation: It really DOES pretty
much come down to cars, SUVs and pickup trucks And while BIG trucks
& buses do use use diesel as opposed to gasoline engines
Requirements and demands are similar enough to cars That I'm
willing to bet that they will be similarly electrified Making
today's discussion relevant to ~ 75% of our current transportation
energy But electrification strategies DO CHANGE based on a
vehicle's: Average length of tripMaximum length of trip Type of
trip (city stop & go vs. highway near constant speed) Number of
trips per day / time spent idle between trips / WHEN idle...
Slide 7
Vehicle-to-Grid (V2G) Power Flow Regulations and Building Codes
Review by the AVTA - INL
http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/evse/v2g_power_flow_rpt.pdf
No surprise: Family vacations & visits are among our longest
trips (~ 15-40 miles) But next longest are our immensely more
frequent work-related trips (~ 15-30 miles) Length of our trips
figures into maximum range expected of an electric vehicle Which
led Department of Energy labs to study our driving habits:
Slide 8
Vehicle-to-Grid (V2G) Power Flow Regulations and Building Codes
Review by the AVTA - INL
http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/evse/v2g_power_flow_rpt.pdf
Classifying trips by their destination: Shows that most of our
driving is shorter trips to work / school / stores: Most frequent
type of trip figures into typical range of an electric vehicle
Slide 9
90% of the time our cars are parked in one of only two
locations: 60 % of time at home (blue) + 30% of time at work
(green) 40% of the time "fleet" trucks are parked at their base
(red) But they are gone gone (presumably on the move) the rest of
the time Fraction of time spent (available) at different locations
figures into recharging of an electric vehicle Vehicle-to-Grid
(V2G) Power Flow Regulations and Building Codes Review by the AVTA
INL: http://www1.eere.energy.gov/vehicl
esandfuels/avta/pdfs/evse/v2g_pow er_flow_rpt.pdf Or, figuring out
where our vehicles spend most of their time:
Slide 10
Plug in Hybrid Vehicle Infrastructure Review, Kevin Morrow
Donald Karner James Francfort - DOE 2008
http://avt.inel.gov/pdf/phev/phevInfrastructureReport08.pdf Are
these trends changing? Yes: "Gotta have a pickup, SUV, or van!""Gas
crisis is over, hit the road!" "Drive farther and...""Rack up those
miles!"
Slide 11
What then are the goals and priorities in electric car design?
For fossil-fuel-plant-charged electric car, onboard 60% conversion
is misleading NET fossil fuel energy conversion rate is one third
of that ~ Same as gas-fueled car An Introduction to Sustainable
Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm + OR 17 21% x
59 62% x 33% 19.5 - 20.5% x 17 21% = 1 Gasoline Car Efficiency:
Electric Car Efficiency: To get rid of fossil-fuels, right? Hold on
a minute! Dont forget this slide from the preceding lecture:
Slide 12
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Abandoning
gas just shifts problem to largely fossil-fueled Grid! And right
now, our cars burn their fossil fuel (gasoline) more cleanly than
many of our power plants burn their dominant fossil fuel (coal)
This is changing, but change will take decades to complete Until
then: Totally electric cars will be as dirty as current gas cars So
wisest priority might may NOW be: Gasoline cars using less gasoline
This is what hybrid electric vehicles (HEVs), such as the Prius,
are all about But you have to concede that our current love for
hybrids is as much about: Saving our pocketbooks (gas $) as it is
about saving the planet Nevertheless, we got this one right. And
one of my engineering maxims is: Always take credit for your
accidental successes as youll surely be credited for your
accidents
Slide 13
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Hybrid
electric vehicles are thus about reducing gasoline consumption From
last lecture, power required for highway driving was: P highway =
air c drag A car velocity 3 air = air density c drag = drag
coefficient A car = cars cross-section To save fuel need: Smaller,
skinnier, more slowly moving cars But power required for city (stop
and go) driving was: P city = Mass car velocity 3 / 2
distance-between-stops To save fuel need: Lighter, more slowly
moving cars, stopping less Here is the first BIG potential savings
exploited by hybrids: Recycle most of the cars kinetic energy when
it stops Via regenerative braking / kinetic energy recovery systems
(KERS)
Slide 14
Recycling is made possible by the duality of electric
motor/generators Gas or diesel internal combustion engines (ICE)
cannot recycle energy Fuel is burned once => Producing
combustion gases + heat => Vast expansion, driving pistons =>
Motion But recycling is possible in any vehicle incorporating an
electric motor/generator: When accelerating or offsetting losses to
air friction: Motor/Generator draws out energy from storage When
decelerating (indeed, in order TO quickly decelerate!):
Motor/Generator puts energy back into storage
Slide 15
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm But this
assumes that the energy storage unit itself is reversible:
BATTERIES: We know that batteries CAN be rechargeable But some do
this better than others. Further: Number of recharges / Rates of
charge-recharge will now be important FUEL CELLS: We also know that
they can be recharged (refueled) But how well, how many times, how
quickly? Part of this is evaluated by an energy storage systems:
Round Trip Energy Storage Efficiency In other words: Of the energy
I put in, what fraction do I get back out?
Slide 16
From my Batteries and Fuel Cells lecture: Batteries and Fuel
CellsBatteries and Fuel Cells Energy recovery from hydrogen fuel
cells is HALF that of batteries U.S. National Renewable Energy Lab:
"Hydrogen Energy Storage Overview"
http://www.nrel.gov/hydrogen/pdfs/48360.pdf Round-trip energy
storage efficiency for batteries and fuel cells Hydrogen Fuel Cells
Batteries
Slide 17
http://www.pv-magazine.com/archive/articles/beitrag/advancing-li-ion-_100006681/501/#axzz3W4O57Ut4
But those data were for energy storage in Grid load leveling Here
are data for more typical batteries, including lead acid & Li
ion used in cars: Some of these entries are still for larger or
more advanced versions But message doesn't seem change: Batteries
are still about twice as efficient: Batteries ~ 80% vs. Fuel cells
~ 40%
Slide 18
To me, this seems to knock hydrogen fuel cells out of the game:
Or at least out of the transportation game Because for regenerative
braking / KERS to work well: We need to repeatedly recycle kinetic
energy - every time we slow down! Its not just ONE energy round
trip, its one after another after another... Storage: Kinetic
energy:Recovered afterRecovered after Recovered after 1 st
deceleration:2 nd deceleration:3 rd deceleration:
Battery100%80%64%51% Fuel cell100%40%16% 6.4% Both storage methods
degrade effectiveness of KERS, but fuel cells eviscerate it!
Undercutting improvement offered by any electric car design
Argument (and numbers) led me to drop hydrogen fuel from this
lecture An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 19
Also important for batteries: Charge/discharge rates + Possible
cycles Data from the "Battery University" for: Lead Acid / NiCd /
NiMH / Li ion (3 types) Lead Acid / NiCd / NiMH / Li ion (3 types)
Ive superimposed highlighting for: Best data in green / Poorer data
in red Best data in green / Poorer data in red Consistent with its
current vehicle use, Li ion batteries win across the board:
Density/Cycles/Volts/Current/Maintenance
Density/Cycles/Volts/Current/Maintenance Only negative: Dont
trickle charge (easily avoided in charger design) (easily avoided
in charger design)
http://batteryuniversity.com/learn/article/secondary_batteries
Slide 20
But in addition to exploiting electric motor/generator duality,
electric car designs exploit another characteristic of electric
motors: Electric motor torque and power vary little with rotational
speed vs. Torque/power bands of internal combustion engine (ICE) -
from last lecture: Both torque and power fall off precipitously at
high/low speeds: Which is why with a stick-shifted ICE: - You must
start in 1 st gear (and carefully slip clutch) - Because you'll
almost certainly stall in other gear For all of their vroom, vroom
roaring: Internal combustion engines are real whimps at low &
high speeds An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
http://en.wikipedia.org/wiki/Power_band
Slide 21
With their 3, 4, 5 or more different gear ratios: Which is why
you need to add big, complex, expensive transmissions Engine's
Speed Car's Speed 4000 RPM 0 MPH 1 st Gear 2 nd Gear3 rd Gear4 th
Gear 70 MPH Or the more recent alternative of "continuously
variable transmissions:" http://nissanaltimaaustin.com/altimas-
cvt-keeps-moving/
Slide 22
Transmissions must provide many, many possible input to output
gear ratios Which must be either manually switched by the driver
Or, in US, automatically switched by the transmission itself
Optimum ratio, at any given time, depends not only on the vehicle's
speed But also on if you want to accelerate more rapidly AND on if
you want to burn less fuel Meaning that modern transmissions are
computer-controlled marvels/beasts With built-in programming that
reprogram's itself based on driver's habits! This makes a
"transmission" very different than a "gearbox" Gearbox can be as
simple as two fixed gears, one small, one large Reducing motor's
naturally high speed (= "1-speed transmission") The need to add a
"transmission" is a big deal
Slide 23
Fixed single-ratio (1-speed) gearbox: This one is built right
onto the end of the electric motor of the electric motor (often
just called a "gear motor") (often just called a "gear motor")
Speed/acceleration/fuel-economy sensing, computer-controlled,
multi-gear ratio, ICE automobile transmission: "Gearbox" vs.
"Transmission" Top:
http://electronics.stackexchange.com/questions/26175/automating-music-box-with-electric-motor
Bottom: http://pixshark.com/automatic-gearbox-diagram.htm
Slide 24
Electric motors (e-Motors) can use simple (or no) gearbox
because: Their torque/power bands are VERY different: Electric
motors don't wimp out at very low speeds! From BMW's eDrive system
(using 175 kW electric motor with Li ion battery): "full torque,
which is typical for electric motors, is immediately available from
a standstill and does not need to be built up first via the engine
speed, as is the case with combustion engines." 1 1)
http://www.bmw.com/com/en/newvehicles/i/i3/2013/showroom/drive.html
Slide 25
Is compounded, on left, by complexity/size of the
to-be-attached gasoline ICE Driving us to use single large ICE +
single large transmission to power any of automobile's wheels that
are going to be powered Despite the fact that, when going in
anything other than a perfectly straight line, all of the wheels
want to turn at different speeds! Real solution, possible with
compact electric motors, is to give each wheel (or pair) an
independent drive system! The complexity of this vs. that:
Slide 26
Thus many Hybrid electric vehicles (HEVs) eliminate
transmissions: At least in the electric half of these (super car to
people's car) hybrids: Ferrari LaFerrari: ICE driving 7-speed
transmission e-Motor is between ICE/transmission & rear wheels
Thus charged by ICE thru transmission (or from wheels) But directly
driving wheels w/o benefit of transmission Jaguar C-X75:Diesel-fed
gas turbines charging battery Four e-Motors (one per rear wheel)
directly driving wheels BMW i3:ICE driving e-Motor charging battery
e-Motor directly driving 1-speed transmission to rear wheels Honda
Accord:LOW/MED SPEED: ICE driving e-Motor charging battery e-Motor
directly driving wheels HIGH SPEED: ICE driving wheels via 1-speed
transmission Le Ferrarri:
http://auto.ferrari.com/en_EN/sports-cars-models/car-range/laferrari/
Jaguar C-X75: http://en.m.wikipedia.org/wiki/Jaguar_C-X75 BMW i3:
http://en.m.wikipedia.org/wiki/BMW_i3 Honda Accord:
http://www.greencarreports.com/news/1087518_2014-honda-accord-hybrid-has-no-transmission-how-it-works
Slide 27
Full connection, engine/motors all the way to wheels =
drivetrain Because we use one gasoline ICE with one transmission,
our classic drivetrain is: But in a hybrid electric vehicle, we'll
have at least an ICE engine + an e-Motor They can be configured in
SERIES So that everything is always turning Or they can be
configured in PARALLEL Where one motor/engine can be connected
while the other is disconnected (or e-Motor remains connected but
just spins idly) An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Gas Engine
Multi-speed Transmission Gas Tank
Slide 28
What was that about electric motor just spinning idly? A
gasoline engine never spins idly (you'd have to force all its
piston valves open!) But electric motor/generator, w/o electrical
connections, is easy to turn Requiring ~ zero applied power / zero
applied torque But when connected there's a strict relationship
between desired speed vs. power Powered, but with no load, it
achieves a specific speed for specific power PULL speed down (by
attaching it to a load) and it consumes excess power PUSH speed up
(by driving IT with something else) and it generates power Hybrid
vehicles can exploit all of these modes of operation! An
Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 29
Classic hybrid drivetrain is parallel: TOP battery powered
electric motor/generator system is connected during: Regenerative
braking: Power from wheels => battery Or possibly when starting
from stop: Battery / e-Motor power => wheels Filling in until
gas ICE gets up enough speed for adequate torque BOTTOM gasoline
ICE system is connected when: Traveling at higher, steady, speeds
(where ICE torque and power are high) BOTH would be connected when
you need gas ICE to also recharge battery Figure is my modified
version of one at:
http://en.m.wikipedia.org/wiki/Hybrid_vehicle_drivetrain Gas Engine
Multi-speed Transmission Gas Tank e-Motor / Generator
Slide 30
Gas Engine 1-Speed Gearbox Gas Tank e-Motor / Generator But
newer series drivetrain can enhance HEV range/efficiency: Here
wheels are driven ONLY by the electric motor (or motors, one per
wheel) CENTER: Energy stored or released LEFT: Gas ICE + 1-speed
gearbox driving generator sending energy (to center) RIGHT:
Electric motor/generator Using energy (center) to drive wheels OR
During deceleration using wheels to turn motor/generator sending
energy (to center) Figure is my modified version of one at:
http://en.m.wikipedia.org/wiki/Hybrid_vehicle_drivetrain
Slide 31
WHY does series drivetrain enhance HEV range/efficiency? In
earlier parallel drivetrain, gasoline engine was trying to do TWO
things: 1) Drive generator, charging battery = Steady speed /
moderate power 1) Drive generator, charging battery = Steady speed
/ moderate power 2) Drive the wheels = revving up, crashing back
down, revving up... One gasoline engine/transmission design cant do
BOTH jobs efficiently (Its hard to just do crazy 2 nd job
efficiently!) With new series drivetrain, gasoline engine/1-speed
gearbox does only the first job And its the simpler charging job
requiring steady speed / moderate power Allowing full (large,
clunky) multi-speed transmission To morph into simple fixed 1-speed
gearbox Car's Speed RPM 1 st Gear 2 nd Gear3 rd Gear4 th Gear
Slide 32
One downside to extended range hybrid electric vehicles In
earlier parallel drivetrain hybrid electric vehicles (HEVs) Much or
most of the time the gasoline ICE was powering the car With
e-Motor/battery cutting in only when regeneratively braking Or when
taking over from whimped-out ICE at low speeds In newer series
drivetrain extended range hybrid electric vehicles (EREVS):
e-Motor/battery are always driving or being driven by wheels Even
while ICE is charging the battery Thus EREVs must generally have
larger, higher capacity batteries With are still the weakest link
in electric transportation! An Introduction to Sustainable Energy
Systems: www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 33
Leading to all electric "Battery Electric Vehicles (BEVs)"
Which, for two wheel drive only, will revert to a very simple
drivetrain: Not THAT much different from present day gasoline ICE
drivetrain: An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Better
batteries will eventually eliminate internal combustion engines Gas
Engine Multi-speed Transmission Gas Tank e-Motor /Generato r
1-speed Gearbox Battery AC/DC Converter
Slide 34
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm But nearer
term alternative is plug-in electric hybrid vehicles (PHEVs) Which
is essentially the same today's HEV or EREV But with added
component connected to battery: This would begin integration of US
transportation into "the Grid" Why complicate matters (and
vehicles) further: Why not just stick with HEVs or EREVs for now?
Or jump directly to fully electric BEVs? Answers to the final BEV
question: - Batteries aren't yet good enough - Grid is still
dirtier than gas hybrids Answer to preceding question (why not
stick with HEVs or EREVs?): Because there are subtle, and
not-subtle, advantages AC/DC Converter
Slide 35
1)
http://www.publicpower.org/Media/daily/ArticleDetail.cfm?ItemNumber=15901
If (and only if) Grid power were sold at a realistic hour by hour
price: There would be big (unsubtle) advantage for the consumer
Which comes from combination of these two earlier figures: Peak
Grid Power 60% Midnight Noon Midnight 80% Power plants must meet
evening demand But 40% of plants are then idled overnight 60% of
our cars sit at home overnight 40% fleet commercial vehicles also
sit idle in company's lot overnight sit idle in company's lot
overnight If Grid power were market priced, hour by hour: PHEVs
could charge overnight at equivalent of ~ 75 per gallon of gasoline
1
Slide 36
Sounds almost to good to be true? There are significant
complications: 1) We'd need "smart" electric meters recording when
we consume power No problem: Already being installed by many/most
power companies 2) We'd need electrical outlets capable of
supplying charging power Standard US household power outlets are
110 VAC / 15 Amp capacity This is called a Level 1 electric vehicle
charging station 1 With its ~ 1.4 kW max power flow, PHEV would
charge in ~ 5-8 hours Advantages: Existing outlets work, but needed
in garage / parking space Charging PHEV would not overload
household circuits Charging PHEV would not overload household
circuits Disadvantage: Don't come home late or plan on going out
tonight 1) http://secleanenergy.gatech.edu/files/King.pdf
Slide 37
Electric vehicle charging stations (continued) A Level 2
electric vehicle charging station is instead 230 VAC / 30 Amp
capacity 1 Many modern homes have a single 230 VAC / 30 Amp circuit
for electric oven But additional 230 VAC / 30 Amp circuit(s) would
have to be added to garage Requiring licensed electrician to burrow
new lines through walls... With resulting ~ 6 kW max power flow,
PHEV would charge in ~ 4 hours Disadvantages: Cost of installation
Could overload household power with multiple cars Level 3 electric
vehicle charging stations envisaged at 480 VAC / 400 Amp capacity
At ~ 192 kW max power flow, PHEVs could then charge in 1-2 hours
But would overwhelm almost all present day household circuits And
if neighbors copied, could crash local power system 1)
http://secleanenergy.gatech.edu/files/King.pdf
Slide 38
Home Level 1: $878 Home Level 2: $2,146 Apartment Level 1: $833
Apartment Level 2: $1520 Cost of installing Level 1 or 2 stations
in homes and apartment complexes 1 1) Page 31 of http:
avt.inel.gov/pdf/phev/phevinfrastructureReport08.pdf
Slide 39
Next complication: 3) Can the Grid handle millions of new
PHEVs? What if night-charging PHEVs draw more than otherwise idle
40% of Grid power? What if people instead plug in PHEVs when they
first come home from work? For most of us this means evenings when
Grid's already at full capacity Answers require more complex
studies on likely PHEV sales Here are data collected by Tom King of
DOE's Oak Ridge National Lab: 1)
http://secleanenergy.gatech.edu/files/King.pdf
Slide 40
Free to choose their own PHEV charging times, citizens do this:
Projections of daily Grid load with and without PHEVs (winter vs.
summer): 1 PHEV charging only yields seemingly minor increase in
winter peak load Actual data from 6 regional PHEV trials (w or w/o
hourly adjusted power charges): 2 "76% of the electricity used for
charging occurred during off-peak periods, additional 4% occurred
during mid-peak, remaining 20% occurred during peak periods" 1)
http://secleanenergy.gatech.edu/files/King.pdf 2)
http://energy.gov/sites/prod/files/2014/12/f19/SGIG-EvaluatingEVcharging-Dec2014.pdf
Slide 41
Electrification of transportation and the Impacts on the
Electric Grid Tom King, ORNL
secleanenergy.gatech.edu/files/King.pdf So, with free choice, what
is impact of PHEVs upon peak load? Small impact seen in regional
test:But larger impacts predicted: Worst case prediction of
increase in total US peak demand is over 150 GW Current total U.S.
peak power is ~ 1000 GW => Predicted increase is thus ~ 15% May
not sound like a lot, but it's more than enough to worry power
companies
Slide 42
An Evaluation of Utility System Impacts and Benefits of
Optimally Dispatched Plug-In Hybrid Electric Vehicles - NREL
http://www.nrel.gov/docs/fy07osti/40293.pdf What if PHEVs were only
charged in the middle of the night? In middle of night the Grid now
operates at about 60% capacity Could millions of new PHEVs,
charging overnight, push it over full capacity? Apparently not: Old
60% + New (40%) x (60%) => 84% Seemingly still leaving
comfortable 16% excess capacity margin
Slide 43
So today's Grid could handle PHEV's if they charged overnight
What about tomorrow's Grid, making much heavier use of renewables?
If we continue to shun hydro/nuclear power, renewables will have to
be solar/wind From my earlier lecture on A Renewable Distributed
Grid: A Renewable Distributed GridA Renewable Distributed Grid
Solar Power vs. Demand:Solar + Wind vs. Demand: Peak Power Use
Midnight Noon Midnight Power of Renewable at Peak Peak Power Use
Midnight Noon Midnight Power of Renewable at Peak An Introduction
to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 44
Vision of PHEVs charging overnight in our garages just crashed
Diminished role of hydro and nuclear slashes our overnight "base"
power capacity But solar & wind would add new midday /
afternoon capacity Could PHEVs take advantage of this new capacity?
Yes, because: They'd then be parked "at work"Leading ORNL to
propose this: Electrification of transportation and the Impacts on
the Electric Grid Tom King, ORNL
secleanenergy.gatech.edu/files/King.pdf Vehicle-to-Grid (V2G) Power
Flow Regulations and Building Codes Review by the AVTA INL:
http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/evs
e/v2g_power_flow_rpt.pdf
Slide 45 Smart Wireless Power Transfer Electrification of
transportation and the Impacts on the Electric Grid Tom King, ORNL
secleanenergy.gatech.edu/files/King.pdf">
Solar cells would not have to be right in the parking lot
Simplification: Get power via Grid from remote solar/wind farms
Complication: Your car's going to be charging for hours in a public
parking lot You know that you are going get charged for that power
What stops the next car from "borrowing" your paid-up power plug?
Oak Ridge's idea: Forget the plug => Smart Wireless Power
Transfer Electrification of transportation and the Impacts on the
Electric Grid Tom King, ORNL
secleanenergy.gatech.edu/files/King.pdf
Slide 46 Power transformer! It works for charging your electric
toothbrush, it can also work for PHEVs! And the guy in the
neighboring parking spot can't "borrow" anything Unless his car
stands 5" high and can drive in under yours">
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Smart +
Wireless: SMART: RF link is going to ID your car Then, via secure
Internet, check for an approved credit card account And possibly
"talk" to car about amount of energy desired... WIRELESS: In
addition to the wireless communication above, there is: A coil
buried in the parking lot beneath your car A coil buried in the
parking lot beneath your carPLUS A coil built in to the floor of
your car Magnetic induction => Power transformer! It works for
charging your electric toothbrush, it can also work for PHEVs! And
the guy in the neighboring parking spot can't "borrow" anything
Unless his car stands 5" high and can drive in under yours
Slide 47
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm PHEVs /BEVs
seems to be prime customers for midday solar/wind power PHEVs /BEVs
seems to be prime customers for midday solar/wind power But then
you'll drive home, turn everything on, and peak out the Grid! Hold
it! If your car arrives home with its battery still almost topped
off Why not then sell some of its stored energy back to the power
company? Or, cut out middle man, and have car help power your home?
Power company might bite: They had excess power during the day
=> They'd sell to you for $$ Now, early evening, Grid demand is
peaking, power is at its most expensive So they'd buy back power
for $$$ But you need a fully charged up car in the morning to get
back to work Fine, overnight they've got gobs of power => They'd
sell to you for $
Slide 48
Buy at $$, sell at $$$, buy back at $? -($$) + ($$$) ($) = $ =
Your potential profit What's in it for the power companies? In you
case you hadn't notice: You're now part of the Grid's load-leveling
power storage system Alternatives, as discussed in my Power Cycles
& Energy Storage lecture, Power Cycles & Energy Storage
Power Cycles & Energy Storage already cost power companies a
LOT of money Solar and wind power will drive necessary amount of
storage through the roof! So there is almost certainly some sort of
Win-Win pricing structure that will allow both you and the power
company to benefit that will allow both you and the power company
to benefit Through its pricing, the power company could even
"incentivize" you to buy PHEV / BEV equipped with larger battery
than you might need just for driving! An Introduction to
Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm
Slide 49
This idea is called V2G = Vehicle to Grid Many of its champions
are at the University of Delaware An overview article see:
"Electric and Hybrid Cars - New Load, or New Resource?" 1 The
popular press has gotten really excited about this idea But power
companies and representative organizations remain cautious A middle
ground can be found in the National Renewable Energy Lab's report:
"An Evaluation of Utility System Impacts and Benefits of Optimally
Dispatched Plug-In Hybrid Electric Vehicles" 2 And in the Idaho
National Lab's report: "Vehicle-to-Grid (V2G) Power Flow
Regulations and Building Code Review by the AVTA" 3 (from which
data are already sprinkled throughout this note set) 1) Power
Utility Fortnightly December 2006:
http://www.udel.edu/V2G/docs/LetendDenLil-LoadOrResource06.pdf 2)
http://www.nrel.gov/docs/fy07osti/40293.pdf 3)
http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/evse/v2g_power_flow_rpt.pdf
Slide 50
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm What issues
do those reports raise / Why are power companies hesitant? You'd no
longer be just a power customer, you'd be part of the power grid:
Your garage charging station would consume power or deliver power
If it malfunctioned, the rest of the Grid would have to be
protected When it functions, it cannot push power out to Grid if
Grid is being worked upon Less it electrocute some poor line worker
Your house power meter must also be smart enough to collect
information on: Your power consumed vs. time of day or week Your
power delivered vs. time of day or week EQUALS exactly what you'd
also need if you cover your roof with solar panels So this is
already being worked out, making it the easy part
Slide 51
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm But
challenges then diverge from home solar power: Homeowners will
individually contract for solar power installation and connection
Which, with a bit more wire and a smart meter, is pretty easy But
parking lots don't come with buried high power electric cables Nor
do they come with buried smart, magnetically inductive, chargers
Someone (organization, company, government agency) is going to have
install Or, at least instigate, those installations P erhaps by
2030, when millions of PHEVs /BEVs might be charging daily,
aggregate storage capacity will be of interest to big power
companies But before that, power companies will be reluctant to
revamp their whole system Suggesting need for long period of
government subsidy and/or involvement?
Slide 52
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm And then just
think through the details of the PHEV scenario I discussed: At work
your PHEV / BEV gets fully charged in the parking lot You drive
home where Grid (and/or your home) draws power from car Then, in
the depths of the night, your car recharges in the garage That
doesn't really work Your car has got to ARRIVE at work with an
almost empty battery So it has plenty of room to add daytime
solar/wind energy To be borrowed by Grid/home during evening peak
Then recharged only enough to get you BACK to work What if you
unexpectedly add on an errand, drop of the kids, get caught in
traffic? A PHEV's gas tank might save you (assuming you still check
your gas gauge!) But with a battery electric vehicle, you'd be
screwed
Slide 53
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm So what
happens then? Do you somehow program a safety margin into your
car's overnight charge? Does your smart car note your driving
pattern and figure out this margin for itself? Or could everyone
involved agree that cars can arrive at work with extra charge Hey!
What if we instead: Arrive at work with charged cars, Then
discharge to Grid in early morning before solar & wind power
strengthen, Then midday, when solar & wind ARE strong, recharge
our battery, Then when we get home, discharge to Grid to help meet
peak demand, Then in depths of night, recharge our car... Some
graphs might help at this point:
Slide 54
1) Power Demand: 2) Power Production (constant base + solar
peak + wind peak): 3) Location of PHEVs / BEVs: 4) PHEV Grid Charge
/ Discharge (driven by 1, 2, 3): 5) PHEV / BEV onboard energy (with
intent that 2 + discharge of 4 => 1): ALL of the things I was
just trying to balance throughout the day: Home Work Charge
Discharge Charge Discharge
Slide 55
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm This is
really getting really complicated! And we haven't even considered
one of the BIGGEST challenges:
Slide 56 Cost of power Figuring out new cost of business + fair
profit is going to be HUGLEY more difficult!">
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm What is the
appropriate price of power (now varying hour by hour)? Ideally "the
market" should decide, maximizing efficiency and all around benefit
But free market power was tried by many states in the 1990's And
what we got was gaming corporations such as Enron That took the
money and ran, leaving us with brownouts or worse So it's more
likely responsibility will fall on state Public Utility Commissions
(PUCs) PUC's typically work with the public utilities (here, power
companies) To figure out their real cost of doing business (now,
hour by hour) Adding on modest, but supposedly fair, profit =>
Cost of power Figuring out new cost of business + fair profit is
going to be HUGLEY more difficult!
Slide 57
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm Power
companies will have legions of tame experts working the problem
They also fund organizations like the Electric Power Research
Institute (EPRI) So their point of view should be well studied and
represented But will our politically appointed PUC members be
similarly well informed? And will they properly balance corporate
and public interests? Don't get me wrong: I worked for a public
utility for 21 years Not a power company but instead the Bell
System Which was then the telephone company for 80% of America
Public utilities are not the Gordon Gecko lizards that gave us the
Great Recession Most are instead deeply committed to, and proud of,
their history of public service But when you are proud of a history
that has worked You become very reticent about giving up that way
of working
Slide 58
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm So based on
both business uncertainties and corporate cultures The power
industry is very apprehensive about this Brave New World of Power
Thus, if we in the US are to derive maximum benefit from
approaching opportunities: We as citizens had better progress from
"I love wind / I hate nukes" To really understanding the subtleties
of power systems And we'd better also make sure that: Our appointed
PUC representatives are at least as well informed Which would
represent a HUGE change in and of itself as I have never heard a
word of public discussion about PUC appointments BTW: You DO
realize that we're already neck deep into the topic of "Smart
Grids" (tune in for more, next time...)
Slide 59
Credits / Acknowledgements Some materials used in this class
were developed under a National Science Foundation "Research
Initiation Grant in Engineering Education" (RIGEE). Other
materials, including the "UVA Virtual Lab" science education
website, were developed under even earlier NSF "Course, Curriculum
and Laboratory Improvement" (CCLI) and "Nanoscience Undergraduate
Education" (NUE) awards. This set of notes was authored by John C.
Bean who also created all figures not explicitly credited above.
Copyright John C. Bean (2015) (However, permission is granted for
use by individual instructors in non-profit academic institutions)
An Introduction to Sustainable Energy Systems:
www.virlab.virginia.edu/Energy_class/Energy_class.htm