TPTF Update Registration of PUN Facilities

1. TPTF UpdateRegistration of PUN Facilities January 21, 2008

2. PUN Registration UpdateJanuary 21, 2008 • Held conference call with TPTF sub-group on January 13, 2008 • Conference call was well attended by ERCOT representatives and market participants • There was much good discussion on the call around PUN modeling and registration issues • No clear consensus or answers emerged but key issues were more clearly identified • Key issues as summarized by John Adams are presented on next page

3. PUN Registration UpdateSummary of Issues Identified on Conference Call • Ensure that any logical grouping of PUN generating units is consistent with the PUCT rule creating the Nodal market • Determine how to define the “grouping” of PUN units into “logical” combined cycles so that using existing combined cycle code does not increase the work load of the QSE in populating COP rather than reducing it by creating a large number of potential configurations for which bid curves and limits must be provided • Determine how to define transitions between registered logical configurations of PUN units • Determine how to map logical configurations of units back to the physical representations used in reliability modeling so that ERCOT can model accurate physical representations of post-contingency responses in the ERCOT planning process • Define how offer curves will be matched to registered capability (which must match the physical models) • Define how ancillary service capabilities will be defined for logical units

4. PUN Registration UpdateNext Steps • Reconvene subgroup to focus discussion on identified issues

5. PUN Registration Update Questions?