Transcript Integrating Wind Power into the Electric Power System Ed DeMeo Michael Milligan

Integrating Wind Power into the
Electric Power System
Ed DeMeo
Renewable Energy
Consulting Services, Inc.
Michael Milligan
National Renewable Energy
Laboratory
Technical Advisor, Utility Wind
Integration Group
Consultant, National Wind
Technology Center
Michigan Public Service Commission Wind Forum
April 25, 2007
Lansing, Michigan
Overview
 Integration Issues and Wind
Economics
DeMeo
 Electric Utility Planning and
Operations: Wind Impacts Overview
Milligan
 Wind Integration Perspective from
Around the Nation
Milligan
DeMeo
 Environmental Issues: Impact on
Wind Economics and Integration
DeMeo
Key Integration Issues
 Costs (capital, energy, O&M)
 Variability Impacts (ancillary services costs)
 Energy (fuel displacement) and Capacity
(serving demand growth) Contributions
 Environmental Considerations
Wind Energy Cost Trend
1979: 40 cents/kWh
2000:
4 - 6 cents/kWh
(no subsidy)
• Increased
Turbine Size
• R&D Advances
• Manufacturing
Improvements
• Operating
Experience
NSP 107 MW Lake Benton wind farm
4 cents/kWh (unsubsidized)
2004:
3 - 5 cents/kWh (no subsidy)
Today: Somewhat higher
increased commodity costs;
unstable market conditions
Natural Gas Situation
“Today’s tight natural gas markets have
been a long time in coming, and distant
futures prices suggest that we are not apt
to return to earlier periods of relative
abundance and low prices anytime soon.”
– Alan Greenspan, Federal Reserve Chairman,
Testimony at Senate hearing, July 10, 2003
Wellhead gas costs - 2002-2003: $3 - $5/MMBTU
Current prices and projections exceed $6/MMBTU
Cost Comparison
 Wind total capital cost: about $1,600 kW today
 Wind energy cost: about 5.5¢/kWh (6.5¢ without PTC)
 Includes 0.5 to 1.0¢/kWh for O&M
 Wind energy costs are stable over plant lifetime
Natural-gas plant fuel cost (HR 7,000 - 10,000)
$/MMBTU:
¢/kWh:
2
4
1.4 - 2
2.8 - 4
6
4.2 - 6
8
5.6 - 8
10
gas cost
7.0 - 10 fuel only
 Wind-gas synergy: save gas when wind blows; burn
gas to maintain system reliability during low winds
Wind Variability Impacts
 To what extent is wind energy value
reduced by increased operating costs for
the rest of the power system?
 How is the power system’s ability to reliably
meet load demands affected by wind-plant
output uncertainties?
Time Frames of Wind Impact Match
System Operation Tasks/cycles
System Load (MW)
• Power systems can already
handle tremendous
variability
0
seconds to minutes
Regulation
4
8
T ime (hour of day)
16
12
tens of minutes to hours
Load
Following
Days
Unit
Commitment
20
24
day
Scheduling
– Capacity value (planning):
based on reliability metric
(ELCC=effective load
carrying capability)
– Scheduling and commitment
of generating units -- hours to
several days -- wind
forecasting capability?
– Load-following -- tens of
minutes to a few hours -demand follows predictable
patterns, wind less so
– Regulation -- seconds to a few
minutes -- similar to
variations in customer
demand
Where Does Wind Data Come From?
Minnesota: Xcel
• Meso-scale
meteorological modeling
that can “re-create” the
weather at any space and
time
• Model is run for the
period of study and must
match load time period
• Wind plant output
simulation and fit to actual
production of existing
plants
Colorado: Xcel
Ponnequin
Peetz
• Based on actual high-frequency
(fast) system load data and
wind data
• If wind data not available, use
NREL high-resolution wind
production data characteristics
• Impact of the wind variability
is then compared to the load
variability
• Regulation cost impact of wind
is based on physical impact and
appropriate cost of regulation
(market or internally provided)
System Load (MW)
How is Regulation Impact Calculated?
0
seconds to minutes
Regulation
4
8
Time (hour of day)
16
12
tens of minutes to hours
Load
Following
20
24
day
Scheduling
–Realistic calculation of wind
plant output (linear scaling
from single anemometer is
incorrect)
• Based on actual system load data
• …and wind data from same time
period
– Meteorological simulation to
capture realistic wind profile,
typically 10-minute periods and
multiple simulated/actual
measurement towers
– Realistic calculation of wind plant
output (linear scaling from single
anemometer is incorrect)
System Load (MW)
How is Load Following
Impact Calculated?
0
seconds to minutes
Regulation
4
8
Time (hour of day)
16
12
tens of minutes to hours
Load
Following
20
24
day
Scheduling
• Wind variability added to existing
system variability
Implies no one-one backup
for wind
How is Unit Commitment Impact
Calculated?
• Requires a realistic system simulation for at least one
year (more is better)
• Compare system costs with and without wind
• Use load and wind forecasts in the simulation
• Separate the impacts of variability from the impacts
of uncertainty
Days
Unit
Commitment
How is Capacity Value Calculated?
– Generation capacities,
forced outage data
– Hourly time-synchronized
wind profile(s)
– Several years’ of data
preferred
• Reliability model used to
assess ELCC
• Wind capacity value is
the increased load that
wind can support at the
same annual reliability as
the no-wind case
Wind Plant Capacity Credit Ex
Reliability Curves With/Without Win
0.14
Wind Plant ELCC = 45 M
0.12
LOLE days/yr
• Uses similar data set as
unit commitment
modeling
0.10
0.08
0.06
0.04
800
900
1000 1100 1200 1300 1400
Load (MW)
1,087 ELCC Without Wind
1,132 ELCC With Wi
High-Penetration Cases
• Minnesota PUC: 15-25% wind penetration (based on
energy) (TRC)
• California Intermittency Analysis Project (Follow-on to
earlier RPS Integration Study; team participation)
• Pacific Northwest: NW Wind Integration Action Plan (and
Forum)
– Idaho Power: about 30% (peak) (no TRC)
– Avista: 30% peak (no TRC); some informal review at Utility Wind
Integration Group (UWIG)
– BPA: analytical work in progress; integration cost is consistent
with others
– Potential follow-on work to the NW Wind Integration Action Plan
(NWIAP) on regional basis
– Northwest Wind Integration Action Plan:
http://www.nwcouncil.org/energy/Wind/Default.asp
Renewable Energy Studies in CA
• RPS Integration Cost Analysis: NREL, ORNL,
Dynamic Design Engineering, California Wind
Energy Collaborative for the CA Energy
Commission
– Used actual renewable generation, load, and
conventional data from ISO Power Information
database
• GE/Exeter/Davis Intermittency Analysis Project
for the Energy Commission
– Analysis of future scenarios of renewable energy
• Both analyses looked at wind, solar, geothermal,
and biomass
CA RPS Integration Cost Project
• Examining impacts of existing
installed renewables (wind 4% on a
capacity basis)
• Calculated regulation, load
following impacts of all renewables
• Capacity value (effective load
carrying capability, ELCC) for all
renewables
• Regulation cost for wind
$0.46/MWh
• Load following: minimal impact
• Wind capacity credit 23%-25% of
benchmark gas unit
http://www.energy.ca.gov/reports/reports_500.html
Regulation and Capacity Value:
RPS Integration Study
40%
35%
30%
Wind (Northern Cal)
25%
Wind (San Gorgonio)
Wind (Tehachapi)
20%
15%
10%
5%
0%
2002
2003
2004
0.60
Regulation Cost $/MWh
ELCC % of Rated Capacity
45%
0.50
0.40
Wind (Total)
0.30
System (Total)
0.20
0.10
0.00
2002
2003
2004
3-Yr Avg
•
California Intermittent Analysis
Up to 24% wind (rated Project
capacity to peak)
• Savings
– WECC nearly $2B
– CA $760M
• Wind forecast benefit
$4.37/MWh
• Regulation cost up to
$0.67/MWh
• Unit commitment w/forecast
results in sufficient load
following capability (and no
load following cost)
•http://www.energy.ca.gov/pier/notices/
Load Following Impacts in CA
• RPS Integration Cost Analysis found little
discernable impact
– Deep dispatch stack provided by market
• IAP found similar result
– Deep CA dispatch stack, augmented by the
Western electricity market
Factors that Influence Integration
Costs: Results and Insights
• Wind penetration
• Balancing area (control area) size
– Conventional generation mix (implication for higher penetration
and new balance-of-system capabilities
– Load aggregation benefits
•
•
•
•
•
Wind resource geographic diversity
Market-based or self-provided ancillary services
Size/depth of interconnected electricity markets
Unit commitment and scheduling costs tend to dominate
Realistic studies are data intensive and require
sophisticated modeling of wind resource and power system
operations
Emerging Study/Methods
Best-Practices
• Start by quantifying physical impacts
• Divide the impacts by time scale corresponding to grid
operation cycles
• Analyze cost impact of wind in context of entire system in
each time scale based on physical requirements
– Load variability
– Wind variability
– System operator must balance TOTAL of all loads and
resources, not individuals
• Capture wind deployment scenario geographic diversity
through synchronized weather simulation
• Re-create “real” wind forecasts
Stakeholder Review
Emerging Best Practices
• Technical review committee (TRC)
– Bring in at beginning of study
– Discuss assumptions, processes,
methods, data
• Periodic TRC meetings with
advance material for review
• Examples in Minnesota, Colorado,
California, New Mexico, and
interest by other states
Minnesota 25% Wind Energy
Penetration Study (MN DOC 2006)
For 3500 to 5700 MW of wind generation
delivered to MN load (15 to 25% of retail
electric energy sales in 2020)
 An increase of 12 to 20 MW of regulating capacity
 No increase in contingency reserves
 An increase of 5 to 12 MW in 5 minute variability
 Incremental operating reserve costs of $0.11 per
MWh of wind generation in the 20% case
Minnesota 25% Wind Energy
Penetration Study (MN DOC 2006)
 Bottom Line: The addition of wind generation to supply
15, 20 and 25% of Minnesota retail electric energy sales
can be reliably accommodated by the electric power
system
 The total integration operating cost for up to 25% wind
energy is less than $4.50/MWh of wind generation.
Key drivers are:
 A geographically diverse wind scenario
 The large energy market of the Midwest Independent System
Operator (MISO)
 Functional consolidation of balancing authorities
 Sufficient transmission (i.e. minimal congestion)
System Operating Costs Impacts:
Results from Recent Studies ($/MWh)
Study
UWIG/Xcel
Pacificorp
BPA/Hirst
We Energies
Xcel/PSCO
Xcel/MNDOC
MN/MNDOC
MN/MNDOC
Range of System Operating Cost Impacts
Studies Conducted To Date
6
1/2 ¢/kWh
4
2
0
0
5
10
15
20
25
30
Wind Penetration (% of System Peak Load)
All results to date fall within the crosshatched area
GE Energy/NYISO/NYSERDA
New York Wind Evaluation
 Comprehensive study of wind’s impacts on transmission
system planning, reliability and operations
 3,300 MW of wind in system serving 34,000 MW of
customer load (10% wind penetration)
 Energy prices based on functioning commercial
wholesale markets -- day-ahead and hour-ahead
 All previous studies based on operating costs only
 Assumes wind is a price-taker
 Market (demand-supply balance) sets price; wind
generators are paid the market price
GE Energy/NYISO/NYSERDA
New York Wind Evaluation
 Overall Conclusion: NY State power system can
reliably accommodate at least 10% wind (3,300 MW)
 Minor adjustments to planning, operation and reliability
practices
 Total NY system (less wind) variable operating costs (fuel,
plant startup costs, etc.) reduced by $350 M
 State-of-the-art wind forecasting contributed $125 M of this
reduction (about 80% of perfect-forecast value)
 Electricity costs reduced statewide (0.18¢/kWh -- all kWh)
 System transient stability improved
Wind’s Contributions
to Electric Power
Energy: displacement of fossil fuels
 In most cases, this is the primary motivation.
Previously existing power plants run less, but
continue to be available to ensure system reliability.
 Contrary to common lore, addition of a wind plant
requires NO new conventional backup generation
to maintain system reliability.
 In many cases, natural gas is saved, reducing total
system operating costs. In all cases, overall
emissions are reduced.
Wind’s Contributions
to Electric Power
Capacity: meeting new load growth
 Wind generally less effective in this respect than
conventional generation. Winds may be low during
peak electricity demand periods.
 But addition of a wind plant will allow some new load to
be served. The amount depends on many factors.
Examples:
New York
Long Island
Minnesota
about 10%
about 40%
about 10%
 With experience and over time, operating strategies and
generation mix will evolve so that combinations like
wind, hydro and natural gas will serve new load reliably.
 IEEE Power Engineering
Society Magazine,
November/December
2005
 Utility Wind Integration
Group (UWIG): Operating
Impacts and Integration
Studies User Group
 www.uwig.org
 UWIG Summary:
Key Points from IEEE
Power Engineering
Society Magazine,
Nov/Dec 2005
 www.uwig.org
Environmental
Tradeoffs
We need to evaluate environmental
impacts on a relative basis.
No energy-generation approach is
without impacts.
The choice is wind vs. something -not wind vs. nothing.
Audubon Magazine,
September 2006
feature article on
wind power
“We can’t lose sight of the larger
benefits of wind,” says Audubon
Washington’s Tim Cullinan. “The
direct environmental impacts of
wind get a lot of attention,
because there are dead bodies
on the ground. But nobody ever
finds the bodies of the birds
killed by global warming, or by
oil drilling on the North Slope of
Alaska. They’re out there, but
we don’t see them.”
Environmental
Benefits of Wind
 No emissions of any kind during operation
 No SOx, NOx, particulates or mercury
 No contributions to regional haze
 No greenhouse gases
 No toxic wastes or health impacts
 Nuclear waste transport and storage unresolved
 Respiratory diseases of growing concern
 No water consumption or use during operation
 Water availability a looming crisis in the Western US
Environmental
Benefits of Wind
 Global climate change concerns can no longer
be ignored by any legitimate political entity
 Most environmental scientists view this as by far the
most serious environmental issue facing society
 Unavoidable evidence mounting
 Very few doubters remain
 Not many arrows in the quiver to address this
concern
 We need them all
 Wind energy is one of them
Paul Anderson, CEO of Duke Energy
(Southeastern Utility, Coal/Nuclear)
Lobbying for tax on carbon dioxide emissions
“Personally, I feel the time has come to act to take steps as a nation to reduce the carbon
intensity of our economy. And it’s going to
take all of us to do it.”
– Paul Anderson, quoted in AP press release, published April 7, 2005
Wind Contributions in Europe
and the United States (2006)
 Germany
85,000
22,000
7
 Spain
50,000
11,600
8
 Ireland
5,500
600
6
 Denmark
4,200
3,100
30
900,000
11,300
 USA
* Approximate values
0.6
Contrasting Approaches to Accommodating
Wind Power in Europe and in the U.S.
Europe
Wind power is environmentally preferred. How can
we best accommodate it within the existing power
system?
U.S.
OK, we’ll accept wind into the existing system, but it
will follow our traditional rules and procedures.
A change in mindset is needed in the U.S. It will not
come from within the power sector, whose responsibility
is reliability, not change. Change, and the incentives to
enable it, must originate in the policy sector.
The Climate Change Threat Is A
Major Business Opportunity
 Technologies to reduce CO2 emissions are
needed worldwide
 Industries producing them will provide
employment and profits
 Countries that produce them will enjoy export
potential and trade-balance benefits
 Countries that do not may miss out on one of
the 21st Century’s best business opportunities
Bottom Line on
Wind Power
Wind power is a very low carbon,
affordable, domestic energy source
It can make a large contribution to the US
economy -- 20% of electricity and more
As a responsible society, we need to use it
-- and use our ingenuity to resolve the
tactical issues it presents