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Using Economic Costs to Design Time-of-Use Prices: A Case Study. American Public Power Association Business & Financial Conference Hyatt Regency Savannah, Georgia September 13-16, 2009 Presentation by: John M. Kelly Director of Economics and Research American Public Power Association
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Using Economic Costs to Design Time-of-Use Prices: A Case Study American Public Power Association Business & Financial Conference Hyatt Regency Savannah, Georgia September 13-16, 2009 Presentation by: John M. Kelly Director of Economics and Research American Public Power Association Washington, D.C.
Largely a “How to” Presentation … Rather than “Why?” But …
Why Economic Costs? Should Rate Patterns be Based on: Tradition … inertia … and happenstance; OR A careful weighing of the relevant factors [costs] with a view of guiding consumers to make efficient use of the facilities that are available? — William Vickrey, 1955
Why Economic Costs? 1. We are bombarded with information; 2. We have to sort the trivial from the important/relevant; 3. If we do not, we are lost in terminal overload; 4. The criteria for sorting must involve context and theory-- the larger perspective. [For example, “What does the term cost mean, what is relevant and what is not?”].Stephen Jay Gould
Why Economic Costs? Generally, Pragmatically … • When prices reflect costs, • good economic things happen • when they don’t, bad things happen • Intuitively what competitive business do • They Work
Why Economic Costs? • Relevancy – Focuses on relevant cost of business decisions (how “bottom line” affected) • Efficiency • Efficient use of current facilities (lowers average Cost/price of Electricity Service • Efficient consumption (residential & business) • Sustainability -- Reflects prices in competitive market
Why Economic Costs? • Equity – Eliminates cross-class subsidies • Transparency (v. traditional cost of service)
Efficiency and the Structure of Electricity Prices Rate StructureCapacity Utilization? Flat Rate ? ? ? ? ? ? ? ? ? ? ? Time-Varying Rate ? ? ? ? ?
Efficiency and the Structure of Electricity Prices Rate StructureCapacity Utilization? Flat Rate 45% --55% Time-Varying Rate 65% -- 75%
APPA DEED Project • Sponsored by APPA Demonstration of Energy-Efficient Developments • Practical and Useful TOU Pricing Methodology • Grand Haven (MI) Board of Light & Power • 13,000 customers • $26 million revenues
Task Essentially is to … • Forecast structure of wholesale power prices based on past prices and utility budget information … • Adjusting for market power and price anomalies so to reflect economic costs • Determine seasons and daily time periods
APPA DEED Project (continued) • Commons costs of power supply (generation plants/wholesale purchases) not allocated • Wholesale Pricesused to design structure of retail prices • Quantitative methods used to determine seasons and time periods (versus visual inspection of graphs)
Steps for Developing TOU Prices Based on Economic Costs (Short-Run Marginal Costs) • Collect and Review 4-5 years of data on: -- Hourly Wholesale Market Prices -- Utility Sales and Revenues • Determine Seasons • Determine Daily Cost/Price Periods for Each Season • Calculate Average Period Costs • Estimate Revenue Impacts • Adjust TOU Price Structure to Recover All Power Supply Costs
Basic Data • Four-Five Years of Data • Wholesale Prices – MPPA (project) node prices in MISO wholesale market; • Utility Sales and Revenue • Budgets
Organization & Preliminary Analysis of Data • Review 4-5 years of monthly hourly data, first graphically to identify and appropriately adjust for excessive prices and anomalies. • Compute average hourly prices for week day and weekend (plus holiday) hours. • Adjust increased hourly price by appropriate amounts based on future year budget estimates.
Precision/Accuracy Objection: Forecasts are not precise But … relative to what? Essentially flat prices (or some related standard); or Time-varying costs of electricity power supply?
Precision/Accuracy “One puts more food on the table by shooting at flying ducks than at floating decoys.” William Vickrey
Methods for Identifying Seasons and Daily Time Periods • Visual Inspection of Graphs • Visual Inspection of Graphs - aided by “data mining,” ANOVA, standard deviations, pivot tables, etc. • Economic Estimates of Welfare Losses
Methods for Identifying Seasons and Daily Time Periods 4. *Cluster Analysis 5. *Regression Trees
Determining Seasons (2): Sums of Absolute Differences of Hourly Costs (mill/kWh) Year 2007 May – June = 297 June – July = 267 Average of 2005 and 2006 July Costs May – June = 297 June – July = 159
Determining Hourly Cost Periods(Step 1): Cluster Analysis Dendrogram (Summer Weekdays)
Determining Hourly Cost Periods (Step 2):Duda & Hart Stopping Rule
Determining Hourly Cost Periods (Step 3) Reviewing Resulting Hourly Clusters/Deciding on Number of Periods 1st Cluster: 1 – 7 2nd Cluster: 8 – 9 and 23 – 24 3rd Cluster: 13 – 18 4th Cluster: 10 – 12 and 19 – 22
Recovery of Power Supply Costs • Determine Non-Power Supply Costs for Utility • Determine Non-Power Supply Costs by Customer Class • No Readily Accessible Estimates for GHBLP • Estimated 70-75 percent • 10-15 Percent Increase above wholesale-cost based price structure • (Lincoln Electric System estimates about 10 percent) • Mark up Price Structure Uniformly • Mark up Price Structure Selectively
DEED Methodology versus Traditional (FAC) Ratemaking 1. Standard/Core Methodology for Determining Costs and Prices (not secondary or option) 2. Power Supply Costs (generation and purchased power) not allocated 3. Rate Structure Based on Wholesale Power Market Prices
DEED Methodology versus Typical TOU Pricing • SRMC instead of LMRC • More Pricing Periods • Wider Price Range (Highs and Lows) • More Reliance on Quantitative Methods for Determining Pricing Periods
DEED Methodology versus Real-Time Pricing • Real-Time Pricing -- Ideal or Goal but: • Complexity • Cost • Customer: Understanding and Convenience
Again … Accuracy/Precision versus Relevance “One puts more food on the table by shooting at flying ducks than at floating decoys.” William Vickrey