Western Wind and Solar Integration Study Debbie Lew National Renewable Energy Laboratory SWAT/CCPG Meeting Aug 22, 2007

Overview How can utilities manage the incremental variability and uncertainty of wind and solar? Do geographically diverse wind/solar resources reduce variability and increase transmission utilization? How do local wind/solar resources compare to out-of-state resources in terms of load correlation or cost? How can hydro help with wind/solar integration? The role and value of wind forecasting Can balancing area cooperation help manage the variability? How do wind and solar contribute to reliability and capacity value? To support multi-state interests in understanding the operating and cost impacts due to the variability and uncertainty of wind and solar power on the grid

Tasks Data Collection –Wind and solar mesoscale modeling –Utility load, generator, transmission data Preliminary Analysis –Extensive statistical analysis with various options for wind/solar sites and transmission Scenario Development –In-state vs out-of-state resources –Geographically diverse resources –Mega projects –Best correlated with load Run Scenarios –Examine costs due to regulation, load following, unit commitment –“Dives” to investigate issues such as Hoover –Examine mitigation strategies/options –Determine contributions to reliability and capacity value Draft and Final Report

Current Status Held Stakeholder Meeting Utilities working on data collection Subcontracts for wind meso-scale modeling and utility simulation and analysis being processed. Solar will be next. Updates and information posted on WestConnect website Next stakeholder meeting mid-2008

Kick-off Stakeholder Meeting Held at NREL 5/23/07 with 56 participants Revisions to study scope –Study footprint to include most of WestConnect –Statistical analysis for 10, 20, 30% wind penetration (by energy), with results determining what levels to conduct simulations –Timing doesn’t allow this to feed into Virtual Control Area project –Intra-hour variability will be analyzed with a validated spreadsheet approach instead of PSLF runs –Costs of renewables or benefits from renewables - will separate out variability/uncertainty costs from market competition effects –Transmission scenarios will be rough (crayon level) –Establish hydro task force Study completion to be pushed back to accommodate revisions

Revised Study Footprint Control areas: APS El Paso Nevada Power PNM Sierra Pacific SRP Tristate Tucson Xcel WAPA

Wind and Solar Mesoscale Modeling Model wind power output for 300 GW of wind farms in Western Interconnection –10 min averages, 2 km grid, m hub height Solar data needs to be modeled –Hourly averages, 10 km grid Mesomodeling data will be made publicly available when completed We are requesting measurements of wind and solar data to validate our mesomodeling

Schedule Kickoff Stakeholder Meeting5/23/07 Data CollectionJun-Dec ’07 Wind/solar mesoscale modelingOct ‘07-May ’08 Preliminary AnalysisFeb-Jun ’08 Prelim. results stakeholder mtgJul ’08 Production Cost ModelingJul ’08-Jan ’09 Interim Technical Results mtgDec ’09 Draft reportFeb ’09 Draft results Stakeholder mtgMar ’09 Final ReportApr ‘09

For more information Debbie Lew NREL