Technical Review Committee Meeting March 16, 2011 Bri-Mathias Hodge Gregory Brinkman Debra Lew

1. Western Wind and Solar Integration Study - Phase 2: Proposed Modeling Efforts Technical Review Committee Meeting March 16, 2011 Bri-Mathias Hodge Gregory Brinkman Debra Lew National Renewable Energy LaboratoryGolden, Colorado USA NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC

2. Background: WWSIS Phase 1 Modeling • Production simulation was conducted with GE MAPS • WECC represented as 14 transmission zones • 5 balancing areas • Hourly simulation over three years • Used 2008 Ventyx database • WECC database - with updates - used for transmission National Renewable Energy Laboratory Innovation for Our Energy Future

3. PLEXOS Overview • MIP formulation allows the addition of constraints on generator operating regions • Can then explicitly model times when cycling occurs • Can easily incorporate cycling and ramping costs • Can consider these costs when making unit commitment and dispatch decisions • Easily switches between explicit transmission modeling and zonal modeling • Can focus on certain regions to examine interesting areas more closely • Allows dispatch at five minute time steps • Can easily examine interesting events in further detail National Renewable Energy Laboratory Innovation for Our Energy Future

4. PLEXOS – Renewable Integration Studies • CAISO 20% Study • CAISO 33% Study • MISO Wind Integration Study National Renewable Energy Laboratory Innovation for Our Energy Future

5. Benchmarking • No benchmarking with Phase 1 MAPS model runs • Plan on benchmarking with TEPPC 2019 ProMod simulations • Intended to be qualitative, not quantitative • Only need to verify that high level information is within a reasonable range • Percentage of capacity by generator type • Percentage of energy by generator type • Total costs • Inter-area flows are of the correct order • etc… National Renewable Energy Laboratory Innovation for Our Energy Future

6. Model Configuration - Timescales • Timescales • Day-ahead unit commitment • Hourly dispatch • PLEXOS allows dispatch at the five minute level • Can use this capability to examine a limited number of interesting events • Can use PLEXOS medium term horizon (load duration curves) in order to optimize over longer time horizons National Renewable Energy Laboratory Innovation for Our Energy Future

7. Model Configuration – Balancing Area CooperationPossible Ideas • Balancing authorities • 5 region • WestConnect, Columbia grid, NTTG, CAISO, Canada • More regions (14?) • Cooperation between BAs • High cooperation • Zero hurdle rates (WWSIS 1) • Medium cooperation • High hurdle rates between BAs on commitment • Low hurdle rates between BAs in hour-ahead and dispatch National Renewable Energy Laboratory Innovation for Our Energy Future

8. Model Configuration - Transmission • Nodal representation vs. Zonal representation • Plan to use Zonal representation, as in Phase 1 • Avoids the explicit planning of low voltage transmission for new renewable sites • New transmission between zones • Plan to use WECC 2019/20 targets and revise/expand with TRC input National Renewable Energy Laboratory Innovation for Our Energy Future

9. Model Configuration - Policy • Production Tax Credit • None in phase 1 • Fixed Operating Reserve Levels • 3% of load spinning per BA in phase 1 • Will need to address if problems occur (e.g., load shedding) • Carbon Tax • $30/ton in phase 1 National Renewable Energy Laboratory Innovation for Our Energy Future

10. Model Configuration - Cycling Costs • The case that includes cycling costs will include these costs in the unit commitment and dispatch optimization algorithms • Optimize around the cycling costs instead of just adding them to the otherwise optimal schedule • GE will also add cycling costs to the results of phase 1 study in order to get a ceiling on maximum costs • Cycling costs considered: • Additional start-up costs • Hot start • Warm start • Cold start • Minimum generation level costs • Additional ramping costs for both normal and fast ramp rates National Renewable Energy Laboratory Innovation for Our Energy Future

11. Proposed Scenarios • Plan to examine the impacts of cycling costs through scenarios that both explicitly consider and neglect the costs of cycling • Varying levels of renewable penetration • 10% • 20% • 30% • Mitigation strategies to be included: • Turning off coal generators in the spring • More flexible thermal generation • etc… National Renewable Energy Laboratory Innovation for Our Energy Future

12. Emissions analysis National Renewable Energy Laboratory Innovation for Our Energy Future • Part-load and full-load properties • Data from Continuous Emission Monitors • Run PLEXOS with unit-specific heat rate curves, emission cost sensitivities

13. NOx emissions vs. heat input, ramp rate NOx curves vary widely between generators Little evidence that dynamic ramping impacts emissions National Renewable Energy Laboratory Innovation for Our Energy Future

14. Difficulties • Poor fits, unexplainable residuals • Possible time lags in the system National Renewable Energy Laboratory Innovation for Our Energy Future