Wind in Ireland Integration and cost issues

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Wind in Ireland Integration and cost issues

• David Milborrow
• david.milborrow_at_btinternet.com

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Authors previous encounters in Ireland

• Participated with ESB and other EU utilities in
  EC-funded studies of wind impacts c.1988
• Member of Advisory Panel which selected turbines
  for Bellacorick, 1990/91
• Invited speaker at IWEA Conference, 1996
• Adviser to developer based in Co Cork on several
  windfarms (some now built) since 1994
• No permanent affiliations!

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Scope of talk

• Assimilating wind
• Issues?
• Problems?
• Costs?
• Limits?
• Extra costs to consumers of adding wind
• Sensitivities?

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Very brief economic interlude

• Much interest in Extra cost of renewables
• Justified by External costs of thermal sources,
  esp Global Warming

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Wind and the competition
Source Author, Windpower Monthly, January 2004
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Levelling the playing field

• Generation cost comparisons not the whole story
• Value of wind Fuel saving value
• CAPACITY SAVING value
  embedded benefits green value
• - costs of backup
• Embedded benefits may be positive or negative

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Who has looked at integration issues?

• Ireland
• ESB (1990), CEGB, and other EU utilities, as part
  of co-ordinated study
• IWEA, Geographical dispersion of wind in
  Ireland, 1999
• Garrad Hassan Impacts study, 2003
• University College, Dublin
• UK DTI/Carbon Trust Network Study, Intermittency
  Module, has c.40 worldwide refs back to 1980
• Grid operators Eltra, NGT, Nordel, and US
  utilities

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Ireland is different

• Could be first self-contained electricity system
  to operate with significant wind input
• Denmark is not isolated, but source of useful
  data, as W Denmark system similar in size
• W Denmark currently runs with wind supplying 20
  of consumption
• Ties with neighbours mean that effective wind
  supply is about 10 - still respectable!

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Integration topics

• Electricity networks
• Behaviour of wind plant
• Assimilating wind into networks
• Storage
• Capacity credit
• Transmission issues
• The future

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• Electricity systems

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Why integrated systems?

• Smoothing
• Demands
• Generation sources
• Peak/average
• House 15
• UK 1.5
• Lower plant margins needed -
• House at least 2peak
• Large electricity system 1.2 peak
• All leads to LEAST COSTS

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Benefits of integrated systems
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Lessons from western Denmark
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Scheduling errors
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Coping with demand variations

• Generator inertia
• Frequency voltage changes
• Demand management
• Pumped storage
• Spinning reserve
• All can cope with demand increase or decrease

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Wind characteristics
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Smoothing makes a difference
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Smoothing of power swings
Time interval 1 hour
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Impacts of 20 wind
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Running electricity systems

• Managing electricity systems is all about
  managing risks
• All estimates of uncertainty come with a range of
  probabilities, and
• Uncertainty margins do not add arithmetically a
  sum of squares law applies

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Estimating the effects of wind

• Establish demand prediction error for
  electricity system
• UK system, 1 hour ahead, 1.3, or 400 MW
• Irish system similar , 40 MW
• Estimate demand prediction error for wind
• Typically 3 standard error for distributed
  wind, 1 hour ahead, (persistence forecast)
• Error with wind, based on sum of squares

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Costing the effects of wind

• Scheduling error with wind enables extra reserve
  capacity needs to be estimated
• Establish cost of extra reserve, based on
• Reduced efficiency of part-loaded plant
• Cost of plant, or,
• Market rates

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Extra back-up capacity
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Extra costs for backup
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Storage

• "Renewables need storage" ?
• Rather misleading!
• Only the intermittent sources
• "Storage can transform the economics of the
  intermittent renewables" ?
• Only if they are very low cost!
• Several studies have concluded that economics
  must be studied separately may be useful to
  system, or as reserve

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Capacity creditsThe Firm power issue



?
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Capacity credits

• Controversial, despite -
• Most authoritative studies confirm wind HAS a
  capacity credit. Includes Ireland
• Note that definitions a muddle
• Some refer to firm power, some to thermal plant
• Firm power is less than rated capacity
• For ALL types of plant!!

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Evaluating capacity credits

• 2 basic methods-
• Establish system LOLP - usually over a year
• Add wind
• Subtract firm power to restore original LOLP
• Or (simplified approach, essentially similar)
• Examine availability of wind at time(s) of peak
  demand

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Capacity credits depend on-

• Amount of wind on system
• Wind speeds
• Wind turbine types
• Winds at time of peak demand
• Utility operating proceduresWhen normalised
  for differences in wind speed, good agreement
  between most estimates for northern Europe

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Capacity credits EU studies
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Capacity credits for Ireland
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Capacity credits monetary values

• These depend on-
• Alternative thermal plant
• Test discount rates and depreciation times
• CCGT plant now most common thermal option in EU,
  costs 500-800/kW
• Capacity valued at 42-83/kW
• No "universal" value

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Benefits of distributed generation

• Reduced losses
• Improved reliability, technical issues
• Reduced costs if line reinforcements can be
  deferred or forgottenBUT
• Siting is important
• too much DG in remote areas will increase losses
• or may advance need for line reinforcements

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Local issues

• Analysis of Delabole wind farm (UK) by SWEB
  showed-
• No problems with flicker
• Peak demands at local substation coincided with
  peak output from wind farm
• Wind farm output "has major influence in
  stabilising the 11 kV voltage level"
• Analysis by P G E also showed benefits from PV
  installation

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Wind integration conclusions

• Modest costs for extra reserve
• Most studies yield similar results
• Capacity credits? Yes, roughlyaverage power
• Problem areas?
• May be preferable, once wind input exceeds 10,
  to curtail wind output on a few occasions
• ..but wind will NEVER impose jolts on the
  system comparable with loss of a circuit of
  cross-channel link

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Carbon savings from renewables

• Variety of answers in literature-
• Due to average emissions from plant mix
• Due to gas plant which will not be built
• Due to emissions from load following (lf) plant
• In daily operations, wind displaces lf plant
• New renewables build forces closure of old
  thermal (usually coal) plant, just as new gas
• Gas plant not built? How can you be sure?
• So another argument in favour of 600-850g/kWh
  from closure of old coal (or oil) plant

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Extra costs of renewables

• Increasing interest in extra costs as States
  define renewable targets
• Estimates of extra costs from various sources
• Author linked to estimate in Power UK, issue 109
  0.3p/kWh to consumer bills for 20 wind by 2020
• Key issues Gas prices by 2020 Wind plant
  costs Price of carbon under ETS

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Possible future Irish scenarios
System MW 5000 5000 5000 6500 6500 6500
Wind 5 10 16 12 20 27
Wind MW 500 1000 1500 1500 2500 3500
Offshore 25 30 40 40 45 50
Date 2005 2008 2010 2010 2017 2025
Source of base data (green) ESBNG authors
assumptions in red
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Future gas prices
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Future wind prices
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Possible costs to electricity consumers of adding
wind
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Thank you!
The End