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• MidAmerican Energy Company• Energy Supply Management• Our typical market day• MEC’s generation portfolio • Reliability responsibilities• Wind variability and its impact

– MISO resource adequacy planning– Locational Marginal Prices– Fossil unit operations

• Wind forecasting

What We Plan to Discuss

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• MidAmerican Energy Holdings Company is a owned primarily by Berkshire Hathaway

• Three predecessor utilities– Iowa Power and Light Company – Des Moines– Iowa Illinois Gas and Electric – Davenport– Iowa Public Service Company – Sioux City

• 723,000 electric customers• 702,000 gas customers• 10,600 square miles from South Dakota to Quad Cities• Communities of Des Moines, Cedar Rapids, Sioux City,

Waterloo, Iowa City, Sioux Falls and Council Bluffs

MidAmerican Energy Company

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• Trading and Market Operations– Manage generation dispatch– Manage FTR hedge strategy– Forecast load and supply– Manage gas supply for generation– Manage submission of bids and offers to MISO– RT Liaison to MISO RGD and generation plants

MidAmerican Energy Supply Management

• Fuel Supply (coal and oil)– Manage generation fossil fuel procurement contracts– Manage fuel transportation contacts – Unit Trains– Emissions allowance trading– Monitor coal quality

• Marketing and Trading Support (back office)– Energy accounting– MISO settlements review and approval– Support for general accounting– Joint owned generation accounting– FERC reporting

MidAmerican Energy Supply Management

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0630 DA staff begins OD+1 preparation– Update gas/oil fuel prices and supply requirements – Hourly load forecast – Hourly wind forecast – 0800 -0815 morning operations call

• GMs plant reports of RT and DA activities• Review limits, ramp rates, testing, de-rates, and scheduled

Outages• Review market prices and expected load demand• Review gas supply requirements for coal units

Our Typical Market Day

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• 0815 -1030 adjust OD+1 offers and bids– Adjust unit limits, prices, dispatch status, ramp rates – Review wind forecast (using latest weather forecast)– 0900 PCI import and initialize demand bid packages (3 Days)– 0930 PCI import wind forecast– Finalize gas supply requirements (coal, CT’s and CCCT)

• 1030 – 1045 Submit DA bids and offers• 1130 PCI - Download submitted DA data OD+1• 1530 PCI - Download physical schedules and DA results• 1550 PCI - Download day ahead LMP (for settlements and P&L

Analyzer)

Our Typical Market Day

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• 0800 Start review of settlements runs• Settlements team review

– Analyze pre-settlement and review shadow for discrepancies– Verify data integrity (data check dashboard)– Modify data as required– Rerun pre-settlement and shadows as required– Resend settlements results to P&L as required

• Settlements Results– Ensures accurate management reporting– Ensures MDMA data submittal accuracy– Ensures accurate shadow for invoice payment

Settlements Team Activities

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• Pre-MISO Integration (Balancing Area Authority)– Provided agency services for BAA– NERC compliance with BAL-001 through BAL-004– Significant bilateral transaction activity– Participant in MISO CRSG– DSM trigger – MAPP Reserve Sharing Pool

• Post-MISO Integration– Significant reduction in agency services For LBA– No BAL-001 through BAL-004 responsibilities– Significant drop in bilateral transactions– Participation in MISO ASM– Increased cost knowledge

Market Participation Then and Now

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• 7,200 MW of Generation Capability– 50% coal– 21% natural gas– 10% nuclear– 19% wind, hydro and biomass (1,348 MW of wind)– 1% by other non-renewable sources

• Peak native load demand – 4,515 MW • MISO participation – load and generation

– Announced membership plans to join – June 2009 – First day of operations – September 1, 2009

Generation Portfolio

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• Storm Lake 1 108 MW PPA• Intrepid 175 MW• Century 200 MW• Victory 99 MW• Carroll 150 MW• Charles City 75 MW• Pomeroy 257 MW• Adair 175 MW• Walnut 153 MW

Total installed 1,392 MW

MidAmerican Wind Farms

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• Pomeroy – 13 Siemens 2.3 MW turbines– Nameplate capacity 30 MW– MISO commercially operational ~ July 31, 2011

• Rolling Hills – 193 Siemens 2.3 MW turbines– Nameplate capacity 443 MW – MISO commercially operational ~ December 15, 2011

• Laurel– 52 Siemens 2.3 MW turbines– Nameplate capacity 120 MW– MISO commercially operational ~ January 15, 2012

MidAmerican Wind Farm Expansions

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• Current capacity 1,392 MW• Expansion capacity 593 MW• Total capacity 1,977 MW• Percent of total capacity 26%

• MEC is #1 in the Nation in ownership of wind generation among rate-regulated utilities in operation or under contract.

Total MidAmerican Wind Capacity

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• Capable of control to MISO setpoint.• All location but one have this capability• Two farms currently registered as DIR• Dispatch is accomplished by:

– Sending to MISO 5-minute max DIR output forecast– MISO generates Unit Dispatch Solution (UDS) for DIR as

well as fossil units– Receive from MISO 5-minute DIR dispatch setpoint– MISO UDS>GMS>RTU>Wind Farm Controller

Dispatchable Intermittent Resources (DIR)

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• Forecast– Runs every minute ( in-house developed .NET application)– Combination forecast

• Persistence • Unit availability• Wind speed• Output curves

– Designed to maximize park output when not being curtailed– Data transfer via API to market interface software

• Transmission of forecast to MISO• Shadow settlement calculation• Analysis

DIR 5-MIN Max Forecast

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• Improved knowledge of real-time capability• More economically dispatched congestion relief• Potential for fewer and smaller swings in prices• Future regulation potential

– Requires accurate 5-minute max output forecasts– Requires market incentives through lost opportunity payments– During minimum generation situations

• Eliminates need for manual curtailments for reliability

Benefits of DIR for MISO Operations

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• Current levels of forecasting (in)accuracy are often cited as a key barrier to significant expansion of wind generation

• Forecasting error by the system operator could have severe reliability impacts; wind asset owners’ forecasting error can have severe economic impacts (for the owner)

– Offering generation in the day-ahead market that may or may not materialize in the real-time market exposes the company to price risk

– Penalties are charged for production above/below day-ahead forecast levels– If MidAmerican drastically under-forecasts wind output, other generation might

be committed such that curtailment of wind generation is required when unexpected winds arrives in real-time and oversupplies the system

– Under the DIR classification, failure to generate the amount forecasted for the following five-minutes will result in additional penalties

Wind Generation Forecasting

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MidAmerican Wind Forecast Methodology

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NWS Weather Data

3rd Party Proprietary Sensor Data

3rd Party Mesoscale

Models

3rd Party Mesoscale

Models

MEC Ensemble Methodology

MEC Ensemble Methodology

Advanced Power Curve

Model

Advanced Power Curve

Model

MidAmerican Model

• MidAmerican’s focus areas for improvement include forecast combination, bias correction and power curve modeling

• Industry as a whole paying increased attention to use of observations for short-term forecasting; holds promise for the industry as a whole, but value for ISO members less clear

European Weather Data

& Models

Canadian Weather Data

& Models

NWS Weather Data & Models

3rd Party Mesoscale Model(s)

3rd Party Mesoscale Model(s)

Vendor Ensemble

Methodology

Vendor Ensemble

Methodology

Advanced Power Curve

Model

Advanced Power Curve

Model

Typical Industry Vendor Method

Focus of continued developmentFocus of continued development

Wind Generation Forecast Results

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Wind Generation Forecast Results

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• Wind speed forecast error is the largest contributor to power forecast error, but other factors can also play a significant role.

– Curtailments – wind speed errors at high speeds do not affect accuracy, but curtailment often occurs when the forecast was for high output, so when it happens, the error is often a significant percentage of capacity.

– Availability – usually less important, but under some conditions (icing, extreme cold), winds might be high as predicted, but farm output becomes impaired significantly or totally

– Power Curve – possibly a driver of error in certain instances, but difficult to measure with confidence

Wind Generation Forecast Error Analysis

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MidAmerican Energy Company’s Wind-Powered Electric Generation

Iowa State PresentationJuly 15, 2011

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Topics

• Iowa Wind Power Review• MEC Wind Project Background• General System and Component Review• Issues Moving Forward

Iowa Wind Power Review

• MidAmerican Energy owns and operates more wind-powered electric generation than any other rate-regulated utility in the nation (1,284.3MW)

• Iowa is the 10th ranked state in the nation in terms of available wind resources

• However, because of a progressive legislative and regulatory environment, Iowa ranks 2nd in actual wind generation capacity and first in percentage of total generation.

Wind Power Background

• Wind Resource– Largest area of risk– Need at least one year of on-site data that correlates well

to local long-term weather service meteorological towers– Site diversification mitigates wind resource risk– Site diversification also allows for more effective energy

dispatch

Wind Power Background

• Land Issues– Landowner relationships are extremely important

• Wind project landowner relationships are not the same as normal utility transmission line relationships. Must get buy-in…eminent domain will not work.

• Wind - 20+ year project with continuous O&M.• Transmission – Build and don’t have significant long term interface

with landowners.

Wind Power Background

• Transmission capacity must be available– Significant development and timing risk– In total MidAmerican will have spent nearly $50m in

transmission upgrades to allow our projects to delivery power

Iowa Wind Resource Map

System and Component Review

Normal Substation Configuration

• Two 161 kV transmission lines• Two 161- 34.5 kV, 72/96/120 MVA

transformers• Power Distribution Center • 38 kV switchgear• Relay Panels, SCADA, & DFR• HVAC, HS & Station Battery• Turbine SCADA and control system

161 kV yard, Transformers & PDC

Control panels and switchgear

Special Features

• Special Protection Schemes (Auto curtailment)– Adjacent system overloads are a concern if certain line

segments are lost • Manual Curtailment via SCADA

– EMS can control generation via analog set point SCADA control

• Generation Following Scheme– One project can track a percentage of another– SCADA set point control from EMS used

Special Features

• Voltage/VAR Controls– Turbines dynamically controlled

• Regulate 161 kV Bus Voltage or• Regulate VARs in or out of 161 kV System

– Voltage control is very effective (when wind blowing)

Transmission Voltage Control

WindVAR Voltage Control

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Installing a Turbine Access Road

Placing an Inverted T Foundation

Completed Foundation

Installing Collector System Cable

Delivery of Blades

Delivery of Blades

Delivery of Towers and Blades

Setting a Tower Section

Preparing to Set the Nacelle

Setting the Nacelle

Assembled Rotor

Setting the Rotor

Setting the Rotor

Setting the Rotor

Aerial Photograph of a Project

Completed GE 1.5-MW Wind Turbines

Issues Moving Forward

• Project System Integration– Forecast native load– Forecast wind generation– Scheduled unit outages and testing– Unit commitment– Purchase and sell energy

Questions?

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