1. Forecasting Power System Hourly Load and Emissions for Air Quality Modeling ERTAC-EGU Model Development Group – Webinar & Outreach slides 2013-2014 Robert Lopez, WI - Presenter

2. Basic Design Approach to Hourly Growth (ERTAC EGU Tool) Reliable, Regular and “Current-but-Stable” Data Open Access for Assumptions & Inputs w/Documentation Easy adjustments (preprocessing forecasts) and sensitivities Hourly sensitivity to growth forecasts combined with realistic plant-to-plant production limits Sensitivity to system characteristics – fuel & unit-type Sensitivity to Peak vs. Annual Trends for Power Production Inherently Simple QA and Troubleshooting

3. Current Status for Growth Forecasts Transitioned a year ago from AEO2010 to AEO2013 for core annual forecast – straightforward for EIA regions but different footprint than first round (now moving to AEO2014) For Peak Hours growth, transitioned first to NERC 2011 data, then in 2013 to NERC 2012 data – more complicated crosswalk – comparison of 10 yr peak [hour] demand (MW) and annual net load (Mwh) forecasts by year provides for an “increment” or “peak ratio” to apply to core annual forecasts Formal group work transitioned from 2007 base to 2011 base Current peak demand data supports regional sensitivities, but not as a specific fuel/type sensitivity – depends now on annual trend as primary driver for fuel/type future growth Current Scenarios are transitioning to greater forecast sensitivity to growth by the different gas unit types (Boiler, Simple Turbines, NG Combined Cycles)

4. Old EIA EMM(NEMS) Map - 2010

5. IPM/NEEDS/ERTAC2010 Regions Map Beta Testing used this Regions Map as a starting Point - reqEMM Crosswalk to apply Rates

6. EIA EMM(NEMS) Map – 2011, 2012, 2013 Annual Growth & Update to ERTAC Core Regions - 2013

7. New EPA Base Case v.5.13 Model Regions – IPM

8. ES&D 2013 – NERC Refined Assessment Regions (data goes back to 2009 & forecasts 10 yrs out – data released late 2013)

9. ES&D 2012 and 2013 – NERC Refined Assessment Regions (data goes back to 2009 & forecasts 10 yrs out – data released late 2012 and late 2013)

10. Key ERTAC Version 2.0-2.2 Issues: Growth Rate Component Current Model demands single regional footprint for annual & peak forecasts – a future version might use two separate footprints w/o crosswalk (see maps) NERC footprint for regions keeps changing on the margin – depends on utility wholesale market participation (see maps) – cross-walk is now updated with each new year forecast from AEO There is interest in enhanced peak demand episode trend projection based on fuel & unit type – best may be trend projection from hourly CAMD data because that data reflects impact of the arms-length wholesale market A similar simplified evaluation led to a version 2.1 forecast with greater annual growth sensitivity by NG unit type (aggregate Gas Boiler generation is not growing in comparison to CCs and CTs due to higher relative boiler heat rates compared to CCs)

13. Model Growth Rates (GR) Calculation by Hierarchy Hour Peak GR = 1.07 Annual GR = 0.95 Transition hours of 200 & 2,000 Non Peak GR = 0.9328 (calculated) 13

14. Capturing Annual Growth Trends Annual US Trends show core coal-to-gas and oil-to-gas production transitions and enhanced demand management along with steadily increasing wind resource – reference natural gas growth forecast (AEO2013 and AEO2014) slows from 2008-2012 accelerated rate Demand Peak Trend projections show broad region picture of a slower peak growth compared to core annual growth, especially through next decade – but trends slowly converge to similar slope going forward Monthly power data clarifies current regional trends With excess installed capacity of base and load following production, marginal pricing of gas vs coal influences wholesale power shares State-by-state trends are not consistent though coal & oil seem on a long term slide and all but two/three states show major NG increase (reflected in 2012 history) 2012 actual summer peak did not exceed 2006/2007/2011 on average across regions but was supported by much more natural gas relative to coal

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19. Example State - Pennsylvania Trend Forecast – Monthly Generation

20. Potential Refinements – EGU System Load & Emissions Forecasts – 2-4 yrs – SIP support Integrating input assumption differences with growth forecast sensitivity tests – like High/Low Gas ( EIA ) & MATS ( non-EIA ) Altering “Best Actual” Forecast from the EIA Reference for sensitivity to different regulatory approaches/concerns Accounting for control system hourly performance differences in the future year ( control percent vs. rate vs. rate variability ) Keeping up with the changing wholesale market and continued grid refinement (system debottlenecking) Improved peak vs annual sensitivities (dual region mapping and better integration of gas unit type growth)