Generation Adequacy Task Force Update to WMS

September 14, 2011

• Items Discussed:– ERCOT load forecast and possible scenarios

to consider

• Proposed “Operational Assessment” format and components.– The Operational Assessment discussion at

GATF included a review of the format and components of the CDR

• Is It really the GATF?

GATF Meeting of Sept. 9, 2011

• Calvin Opheim reviewed the various load forecast scenarios: How they are prepared and the underlying assumptions for each load scenario (e.g., weather, economics, jobs, etc.).

• At this time GATF did not make any specific recommended changes to the load forecasting techniques.

• However, GATF will continue to review the possibility of including a high and low case in the CDR. Depends on decisions made on Operational Assessment defined in the next slides.

ERCOT load forecast and possible scenarios to consider

• ERCOT Staff proposed a change to the CDR. (See ppt. presentation posted at the GATF Sept. 9th meeting titled: CDR Changes for GATF_r2)

• Split the CDR into 2 different reports:– The current CDR format for years 2 through

10.– A “Seasonal Resource Adequacy

Assessment” report for the prompt year.

Proposed “Operational Assessment” format and components

• Assumptions made initially for discussion at GATF:

– The CDR would be issued in January for Year+1 to Year+10 • e.g. January 2012 release would include 2013-2022

– A new report – the Seasonal Assessment of Resource Adequacy (SARA) – would be released in ~April 15 for Summer season and ~October 15 for winter season

• Long-term projections are necessarily based on less certain information than near-term projections

– CDR would continue to be based on assumptions consistent with use of probabilistic target reserve margins, albeit some improvements are being analyzed

– SARA would be based on the most current projections of input data; comparison would not be made to target reserve margin year.

Procedural Changes Proposed

• Approach– Deterministic, illustrating arange of potential values for

uncertain inputs– Incorporate near-term forecasted data, where available– ERCOT independent assessment with flexible assumptions to

address currently-relevant issues (e.g. CSAPR)

• SARA adequacy not based on target reserve margin, since uncertainties addressed deterministically in prompt year.

• Use 3 month-ahead weather outlook to develop base forecast

– Possibly illustrate appropriately high range based on weather and economy (90th percentile temps if base is normal, all time temps if base is above normal?)

– Use latest EILS procurement quantities

SARA

• Resources – potential changes for SARA– Use capacities from CDR – Illustrate with and without planned generation– Reduced by planned maintenance outages– Illustrate range of forced outages– Reflect any uncertainty associated with drought,

environmental restrictions, and other relevant factors that may arise over time

– May be appropriate to look at this on monthly basis due to seasonal outages

• Use of the 13.75% planning reserve margin in this context is NOT APPROPRIATE

Conceptual Differences from Long-term CDR Assumptions

• Instead of a “Planning Reserve Margin”, perhaps the SARA would:

– Calculate two risks:• EEA Risk = Total Resources – High Demand –

90th percentile forced outages – Operating Reserves from Generation

• Capacity Insufficiency Risk = EEA Risk + Demand Response

– If both of these are positive, does that mean No Risk? No

– Is this an acceptable / reasonable / useful measure of risk?

SARA Format Ideas

Comparison of CDR and SARA - Discussion Only2011 CDR View SARA View

Total Summer Peak Demand, MW 63,898 66,500 Use 3 Month Outlook less LAARs Serving as Responsive Reserve, MW 1,063 less LAARs Serving as Non-Spinning Reserve, MW 0 less Emergency Interruptible Load Service 421 less Energy Efficiency Programs (per SB1125) 128Firm Load Forecast, MW 62,286 66,500

Installed Capacity, MW 63,859 63,859 These numbers may be adjusted in both by temp deration factorCapacity from Private Networks, MW 5,023 5,023 These numbers will be updated in both by new PUN surveyEffective Load-Carrying Capability (ELCC) of Wind Generation, MW 822 822RMR Units to be under Contract, MW 0 0Operational Generation, MW 69,704 69,704

50% of Non-Synchronous Ties, MW 553 553Switchable Units, MW 2,962 2,962less Switchable Units Unavailable to ERCOT, MW 317 317Available Mothballed Generation , MW 0 0Planned Units (not wind) with Signed IA and Air Permit, MW 260 260ELCC of Planned Wind Units with Signed IA, MW 13 13Total Resources, MW 73,175 73,175

Reserve Capacity (MW) 10888 6675

Reserve Margin 17.5%The highlighted numbers below are not "real"

Typical August Forced Outage MW 3500High Seasonal Load Forecast Range 2000 If 3 mo outlook is Low, use Normal; if Normal, use High; if High, use Extreme90th Percentile Forced Outage MW 2000Op Risk MW 7500

Responsive Reserves Req from Gen 1,237Regulation Reserves Req 650Operating Reserve Req from Gen 1887

less LAARs Serving as Responsive Reserve, MW 1,063 less LAARs Serving as Non-Spinning Reserve, MW 0 less Emergency Interruptible Load Service 421Demand Response 1484

EEA Risk (Reserve Capacity - Oper. Res. From Gen - Op Risk MW) -2712Capacity Insufficiency Risk (Reserve Capacity + DR - Oper Risk MW - Op Res from Gen) -1228

• Is it really the GATF?

• Isn’t this group really the CDRTF?

• The real question, with no answer from GATF: Do we need a place to consolidate all of the “pieces” under a single “resource adequacy” group?

Post GATF Meeting Discusssion

Next Meeting: October 7th

Questions or Comments?