2009 Scenario Reliability Assessment - NERC

Regional Reliability Scenario Self-Assessments Class 1: under active construction with an expected in-service date prior to January 2012 Class 2: all regulatory approvals, with a signed interconnection agreement, with anexpected in-service date prior to January 2014 Class 3: (gas-fired components): undergoing regulatory review and at least a facilitystudy completed, with an interconnection agreement in active negotiation, with anexpected in-service date prior to January 2014TEPPC constructed the renewable generation mix to add to these resources for the RPS and 15percent Scenario Cases. TEPPC used judgment to create a reasonable distribution of renewableresource types from those being considered by WECC members and a reasonable physicaldistribution of those resources across the Western Interconnection. More information on the mixof renewable resources and their locations can be found in the 2008 TEPPC Annual Report 111 ,and the TEPPC white paper on Renewable Energy Cases. 112Finally, TEPPC added sufficient load-center gas-fired generation to meet reserve margin targets.The addition of renewable resources to the 8.8 percent (RPS) case displaced non-renewableresources that had been needed to match resources with demand, creating an excess of resourcesthat contributed to the reserve target.Due to the nature of the scenario construction process, there is little comparability with theresources in the 2009 Long-Term Reliability Assessment, which represents specific utility plansand their expectations of independent developer behavior, modified by their application ofconfidence factors.Purchases and Sales on PeakWECC does not gather data about contractual sales or purchases, which are in any case largelyirrelevant to the adequacy analysis WECC performs. In WECC’s analysis, resources aredispatched to meet loads subject to transmission constraints. WECC simulates the entireinterconnection, so there is no load or resource that is outside the sphere of the analysis, asidefrom a minimal amount of transactions across interconnection boundaries with MidwestReliability Organization (MRO) and Southwest Power Pool (SPP), which were not included inthe analysis. This treatment of transfers removes any potential for double counting of resources.WECC does not monitor each load serving entity’s supply status, but instead studies the supplysituation of the interconnection as a whole. Because WECC is not reporting any externaltransactions and is only reporting data for the entire interconnection, there is no data to bereported in this section.FuelWECC answers this question through an hourly simulation rather than a simple comparison ofpeak loads and peak resources, so WECC compared the base case with the Scenario Case. Thiscomparison showed the effect of the additional approximately 7 percent renewables penetration.The fuel supply effects are largely a reduction in gas use, on top of whatever reduction in gas usewould come from meeting the RPS requirements in the first place. It is unclear whether a 15percent renewable case increases or decreases fuel supply vulnerability. From the vantage pointof annual fuel use, reduced usage would tend to reduce pressure to develop new and replacementsupplies or expand the natural gas transmission system. The intermittency of wind and central111 http://www.wecc.biz/modules.php?op=modload&name=Downloads&file=index&req=viewsdownload&sid=172112 http://www.wecc.biz/documents/library/TEPPC/TEPPC-15-Renewable_Energy_Generation_Paper_9-12-08.pdf2009 Scenario Reliability Assessment Page 165