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Bounding Value at Risk for Energy Companies with an Interval-Based Algorithm
  • Gerald B. Sheblé and Daniel Berleant
  • Dept. of Electrical and Computer Engineering
  • Iowa State University
  • Ames, Iowa 50011
  • USA
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The Changing Energy Service Company Environment
  • Energy service company background
    • ESCO = Energy Service COmpany
    • ESCOs are electric power retailers
    • Traditionally, rates are set by a regulator
    • Increasingly, deregulation is occurring
    • Market forces are now driving competition
    • A new risk is the risk of going out of business
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Value at Risk – the Concept
  • Value at Risk = VaR
  • VaR consists of
    • an upper limit on acceptable financial loss
    • p(loss will be within the acceptable limit)
  • The limit might be
    • how much the company can lose, and
    • still stay in business
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Value at Risk –  the Concept
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VaR and the ESCO
  • Deregulated energy service companies…
    • are operating in a “typical” competitive mode
    • and must understand and control their VaR
  • A model of VaR for ESCOs is needed
  • To reliably analyze it, we propose to:
    • avoid assuming components are independent
    • use an interval-based analysis algorithm, DEnv
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The Covariance Method
  • Covariance method is relatively fast, easy
  • It requires a correlation matrix
    • (for the uncertain factors)
  • It assumes the uncertain factors are Gaussian
    • This assumption is not always valid
    • Invalid assumptions lead to incorrect conclusions
  • An augmented or different method is needed
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The Historical Method
  • Relies on historical data as problem input


    • But historical data may be insufficient, and
    • The current environment may have changed


  • The historical approach is not always best
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The Monte Carlo method
  • MC involves randomly generating events
    • Events are derived from distribution functions
    • Distributions are often assumed normal
      • (But they don’t have to be)
    • Distributions are often assumed independent
      • (But they don’t have to be)
    • MC is tricky when dependencies among distributions cannot be assigned
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A Model for ESCO VaR
  • We combine three contributors to risk:
  • 1) Market Price Risk
    • Price fluctuation can cause losses in any business
  • 2) Supplier Contract Failure
    • The ESCO’s energy suppliers may not deliver
  • 3) ESCO Contract Default
    • The ESCO itself may be unable to deliver
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A Model for ESCO VaR
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The Model – Market Price Risk
  • Uses a covariance matrix of fluctuations
    • This may be derived from historical data
  • VaR of market price fluctuation is:


  • P is proportion of overall value of...
    • each portfolio component
  •   is the volatility (determines confidence)
  • C is the covariance matrix



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The Model – Supplier Contract Failure
  • Failures may be the fault of
    • GENCOs (generating companies)
    • TRANSCOs (transmission companies)
    • DISTCOs (distribution companies)
    • ICA (Independent Contract Authority)
  • This 2nd VaR component contributes to
    • losses due to ENS (energy not served) model
    • the 3rd VaR component also contributes to
    •    loss due to ENS...
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The Model – ESCO Contract Default
  • ESCOs (Energy Service Companies) may
    • fail to deliver due to supplier failures
    • fail to deliver due to operational failures
  • Major operational failure sources are
    • human error
    • computer error
    • strategic error
  • Operational risk combines those sources


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Energy Not Served (ENS)
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Energy Not Served (ENS)
  • Power undelivered to customer due to
    • Operational failure of the ESCO
    • Failure of suppliers to deliver to the ESCO
      • Supply chain includes
        • GENCOs
        • TRANSCOs
        • DISTCOs
        • Coordinators
        • ESCO

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Cost to ESCO of Energy not Served
  • (Recall ESCO is the energy retailer)
  • Most obviously, there is loss of income
  • Failure to deliver may incur a penalty
    • Customer should be compensated
      • (This may be via rebate or direct payment)
    • Compensation should account for:
      • damage to the customer, and
      • need by ESCO to retain the customer


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Payments Due to ENS
  • Any link in the supply chain to the ESCO
    • ...may cause a failure of supply
    • ...and result in compensation TO the ESCO
  • The ESCO may suffer operational failure
    • ...resulting in payments to the customers
    • Note no standards for this exist yet
    • ESCOs should have a capital fund for this

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Market Price Risk
  • Energy sales depend on supply contracts
  • Contracts may be spot, forward, or futures
  • Contracts are made by a double auction system
  • Astute bidding strategies are a necessity


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Combining the Factors
  • Step 1: get a PDF for each factor
  • Step 2: obtain the PDF for
    • the sum of the factors
    • That is, given random variables,
      • what is the distribution of their sum?
  • Complication:
    • The factors are not independent
      • Worse, we don’t know their dependency
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What Next?
  • Strengthen effects of constraints due to partial information about dependency
  • Address calculation of individual components
  • Continue to develop applications of an interval-based algorithm, DEnv
  • Questions?