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Renewable Renewable Energy:Energy:Energy:Energy:
Essential terms andEssential terms andEssential terms and Essential terms and concepts for citizens concepts for citizens
and advocatesand advocates
Courtesy of NASA
and advocatesand advocates
y
Contact InformationContact Information
P t Sh kP t Sh k
Contact InformationContact Information
Pete ShoemakerPete ShoemakerPacific Energy CenterPacific Energy CenterPacific Energy CenterPacific Energy Center
851 Howard St.851 Howard St.San Francisco, CA 94103San Francisco, CA 94103
(415) 973(415) 973 88508850(415) 973(415) [email protected]@[email protected]@pge.com
The Big Picture
Courtesy of NASA
Courtesy of NASA
The sun is the only input.
Fossil fuels are millions of years of stored sun energy.
Which allows our lifestyle to expand to this.Which allows our lifestyle to expand to this.
Peak Oil
But the Age of Oil is temporary.But the Age of Oil is temporary.
Renewable Energy
And we’ll need a lot of different sources to replace it.
Conclusion
• Fossil fuels are an extremely dense, very portable form of concentrated energy.
• They are impossible to replace directly• They are impossible to replace directly.
• Key #1 to the transition to renewable energy is DIVERSITY.
Types of renewable energyyp gy
1. Hydroelectric1. Hydroelectric
2. Tidal
3. Geothermal
4 Bi4. Biomass
5. Wind5 d
6. Solar (electric, thermal)
Hydroelectric: large scaley gUses water flowing over a generator to spin a g pwheel and create electricity.V “ ”Very “green”.
Problems:
Courtesy of DOE/NREL
Ecological disruption, fish & wildlife
Tidal
Great potential, since t iwater carries
tremendous power.
Problems:Harsh conditions.Environmental disruptiondisruption.
Source: cbc.ca
Geothermal: large scalegUses the heat of the earth to create steam and turn a generatorand turn a generator.No emissions, produces 24/724/7.
Problems:
Courtesy of DOE/NREL
Site specific.Good sites are usually yaway from population.
Geothermal: small scale
Also called “Ground Source Heat Pump”
Uses the stable
Source Heat Pump .
Uses the stable temperature of the earth for heating and cooling
Problems:
Site location.
Expensive up-front.
BiomassSun energy
Stored in plants as they growas they grow
Still there when Can be extractedStill there when they’re harvested
Can be extracted and used
Biomass: BiodieselMade from cooking or other household oil.
Use it in cars just like gasoline.
Biomass: Ethanol (grass) or algae(g ) g
Doesn’t use food.
Much better than corn ethanol.Much better than corn ethanol.
Biomass: Methane
Turns cow dung into fuel.
Very cost-effective for appropriate sites.Keeps methane out of the air.
Wind• AbundantC b l• Can be low-cost
• Fast-growing
Courtesy of DOE/NREL
Problems:• Site-specific
y
• Large up-front cost• Environmental issues• Intermittent production
Windmills: Two different typesDefined by axis of blade rotation:
Horizontal axis(HAWT)
V ti l i( )
Vertical axis (VAWT)
Windmills: Swept area
Potential output is directly related to the input of wind energy: the amount of area “swept” by the windmillgy p y
HAWT: Larger is usually betterHorizontal axis: area = πR²
RR
Doubling the blade length increases the area 4x.
Power in the WindWind power is a VOLUME-based equation
xV = x³
x
xx
10 mph (10 x 10 x 10 = 1000)
5 h
10 mph ( )
( )
Doubling the wind speed increases the
5 mph (5 x 5 x 5 = 125)
Doubling the wind speed increases the potential wind power 8x.
Li htLi ht
Solar: Different TypesLight energyLight energyPhotovoltaic (PV)Electricity produced directly from lightElectricity produced directly from light
Heat energyHeat energyC t t d S l P (CSP)Concentrated Solar Power (CSP)Electricity produced by steam
Solar Water Heating (Solar Thermal)Heat produced in water, can be also used for space heating
All courtesy of DOE/NREL
Conclusion
• Fossil fuels are dirty but predictable in their output.
• Renewables are clean but multi-faceted• Renewables are clean but multi-faceted and variable.
• Key #2 to the transition to renewables is INTEGRATION.
Keys to Transition to Renewablesy
1. Diversity
2. Integration
Wind Array Variability
2007 CAISO (California Independent System Operator) report on Integration of Renewable Resources
PV Array Variability
Jay Apt and Aimee Curtright': "The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays."
The Electric Grid
Electricity can be transported at the speed of light, therefore any point can be said to be connected to all others.
This network is called the GRID and is nation-wide.
Source: onearth.org Source: NREL
The Electric Grid
There are three main components of the grid:
Generation: Creating electricity.
Transmission: Moving it in bulk from t t di t ib ti tgenerators to distribution centers.
Distribution: Bringing it from centers (sub-stations) to individual homes and ( )businesses.
The Electric Grid
Source: PG&E
The Electric Grid
Above 50,000 V (69 kV up to 765 kV)
Step Sub-station
10,000 V (10 kV)
Transmissionp
up
10,000 V (10 kV)Step downDistribution
12 000 V (12 kV)120V – 240V
Generation12,000 V (12 kV)
Step down
Home480V
BusinessSource: NR
Grid Terms
Supply side Demand side
Generation Usage (load)
Grid Terms
Baseload: Minimum amount of power that is l d dalways needed
Seasonal load: Increase in demand in specific times of the year.
Peak load: Maximum amount neededPeak load: Maximum amount needed.
Capacity: Total power that the system can provide.
Grid Terms
BaseloadBaseloadBaseloadBaseload
PG&E 2006 Annual Usage
Grid Terms
Seasonal loadSeasonal load
PG&E 2006 Annual Usage
Grid Terms
Peak loadPeak loadPeak loadPeak load
PG&E 2006 Annual Usage
Highest demand occurs on only a few hours in the year
20000 Th t “50 H ”
14000
16000
18000
The top “50 Hours” represent 0.6% of the total hours in a year
10000
12000
14000
MW
s
4000
6000
8000
Load Duration CurveLoad Duration Curve
0
2000
1 501 1001 1501 2001 2501 3001 3501 4001 4501 5001 5501 6001 6501 7001 7501 8001 8501
Time
Load Duration CurveLoad Duration Curve
Grid Terms
CapacityCapacityCapacityCapacity
PG&E 2006 Annual Usage
Grid Terms
Unused CapacityUnused Capacity
PG&E 2006 Annual Usage
Grid Terms
Spread out the demand and you Spread out the demand and you p yp ycan lower the capacity need.can lower the capacity need.
PG&E 2006 Annual Usage
Grid Terms
Demand Management or
D d id M tDemand-side Management
Load-shifting
“How do you get people to use less power during peak times and morepower during peak times and more during off-peak?”
Demand Management Strategies
1. Reduce overall load.-- Energy efficiency, conservation
2. Inform people so they can cooperate voluntarily.
P bli it “Fl Y P ” l t-- Publicity, “Flex Your Power” alerts3. Create the ability to remotely turn off
t i licertain appliances.-- Smart AC, smart meters, etc.
4 Ch f k4. Charge more for peak usage.-- Time-of-Use rates, Peak-Time pricing
d th… and others.
Grid Integration Challenges
Source: onearth.org
Grid Integration Challenges1. How do you ensure a constant baseload?2 How can you handle daily variability?2. How can you handle daily variability?3. How can you predict output and budget
appropriately?appropriately?4. What storage devices are available and
practical?practical?-- The more storage, the more load shifting possible.
Grid Integration Challenges
1. How do you pay people for renewable energy?energy?
2. How MUCH do you pay people for renewable energy?renewable energy?
3. Should you pay differently for different types of renewables?types of renewables?
Methods of Payment
Two fundamentally different concepts:
Net MeteringServes the onsite load FIRST, then Se es t e o s te oad S , t einteracts with the utility grid.
One meter
Feed-in TariffDoes not serve the onsite load andDoes not serve the onsite load and ONLY interacts with the utility grid.
Two meters
Net Metering
MeterMeter
Customer side Utility side
Net Metering
Generation: 3 kWh Surplus: 2 kWh
MeterMeter
Load: 1 kWhCash credit: $ .602 kWh @ $(going rate)
Customer side Utility side
Net Metering
Generation: 1 kWh Surplus: 0 kWh
MeterMeter
Load: 1 kWhCash credit: $ .00
Customer side Utility side
Net Metering
Need: 1 kWhGeneration: 0 kWh
MeterMeter
Load: 1 kWhCash debit: $ .091 kWh @ $(going rate)
Customer side Utility side
Net Metering
kWh/mo
Average monthly usagePV system production
750 Roll over
500
250
OctoberMay April“SUMMER” “WINTER”
Net Metering
kWh/mo
Average monthly usagePV system production
750The surplus covers the shortfall, and your yearly bill is minimal.
500
250
OctoberMay April“SUMMER” “WINTER”
Net Metering
kWh/mo
Average monthly usagePV system production
750PV system produces less than your yearly usage.
500You pay this amount
250
OctoberMay April“SUMMER” “WINTER”
Net Metering
kWh/mo
Average monthly usagePV system production
750PV system produces more than your yearly usage.
500You are paid a different rate for this amount You are paid a different rate for this amount –– TBD.TBD.
250
OctoberMay April“SUMMER” “WINTER”
Net Metering
PV system production
MeterMeterInverter data
Customer side Utility side
Feed-in Tariff
Generation track
Feed-in (credit) ( )Meter
Usage (debit) Meter
Usage track
Net Metering
MeterMeter
Customer side Utility side
Comparison
Net Metering Feed-in Tariff
1. One meter2. One yearly payment
1. Two meters2 One monthly check2. One yearly payment
(check), net amount3. Often not easy to
d t i PV
2. One monthly check, one monthly bill
3. Easy to determine PV determine PV production
4 Payback can vary
yproduction
4. Payback usually much more predictable4. Payback can vary
depending on your tier usage
more predictable
Rate StructuresNet Metering: Tiered rate—the more you use, the more you pay.
PG&E E-1 Residential Rate 6/1/10
40.0 40.040 0
45.0
29.130.0
35.0
40.0
kWh
11.9 13.515.0
20.0
25.0
Cen
ts p
er
0.0
5.0
10.0
Less than 101% 131% 201% Over 300%Less than100%
101% -130%
131% -200%
201% -300%
Over 300%
Percentage of baseline allocation
Rate Structures
Feed-in Tariff: Fixed rate over time, possibly adjusting for inflation.
20-year Feed-in Tariff
20
25
r kW
h
5
10
15
nts
paid
per
0
5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Cen
Years
Rate Structures
Can have a mixture of bothIn PG&E territory:In PG&E territory:
• Systems from 1 kW to 1 mW (1,000 W to 1,000,000 W) are under Net Meteringare under Net Metering
• Systems above 1 mW are on Feed-in Tariffs
Feed-in Tariffs: How much to pay?
• Should it be higher than non-renewables?
• Should it be fixed or according to some kind of “profitability index”?p y
• Should you pay different amounts for different renewables?renewables?
“Grid Parity”When the price per kWh of electricity from a renewable source is equal to the current average grid price.
PV example:System net cost: $20,000, lifetime maintenance $4,000.
Expected to generate average of 5,000 kWh per year for 30 years, total of 150,000 kWh.
$24,000 / 150,000 = $ .16 per kWh
Current PG&E average price = $ .16 per kWhCu e t G& a e age p ce $ 6 pe
= Grid Parity
Renewable Energy Credits
• Called RECs or “green tags”• The “green attribute” of the power• The “green attribute” of the power• Connected to carbon offset accounting
Central feature of a system to move money from polluters to non pollutersfrom polluters to non-polluters.
Carbon Offsets
• Making activity “carbon neutral”Making activity carbon neutral• Funding projects that remove as
much carbon as you generatemuch carbon as you generate• Additional social & business image
lvalue
Keys to Transition to Renewablesy
1. Diversity
2. Integration
3. Economics
Environmental ImpactL PV i h d
M f t & M t i l
Large PV array in the desert.
T i i
Manufacture & Materials
Construction
Transmission
Generation &
Construction
Maintenance
Keys to Transition to Renewablesy
1. Diversity
2. Integration
3. Economics
4 Environmental impact4. Environmental impact
Keys to Transition to Renewablesy
1. Diversity-- Need a wide variety, fit technology to site
2. Integration2. Integration-- Ensure baseload, reduce variability
3 Economics3. Economics-- Good incentives, fair to all ratepayers
4. Environmental impact-- All aspects of project
Smart Grid
Source: EPRI Intelligrid Architecture
Source: NPR http://www.npr.org/templates/story/story.php?storyId=110997398
Courtesy of NASA