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Appendix D of 2014 TEPPC Study Program – Study Case
Scoping Form
TEPPC 2013 & 2014 Study Programs
Study Case Scoping Form
The purpose of this document is to define the overall scope of a TEPPC study case so that the study requestor,
TEPPC, and the WECC staff have a common understanding of the expectations and limitations of the study that
will be completed.
Study Case Name
Large CA RPS Increase Study Cases
Date of Adoption
Case Number
PC24, EC24-1, EC24-2
Study Timeframe
Study Requestor
CEERT, IID, PG&E
Priority
Pending SWG
Review
2024 & 2034
(10- & 20-Year)
High
Study Case Summary
PC24: Increase to 40% RPS from In-State Resources
10-Year (2024): This case will assume a large CA RPS increase corresponding to 40% RPS from instate renewables, corresponding to approximately 19,800 GWh of incremental renewable energy
(RE). The approximate mix of the additional renewables is as follows, with tweaks based on actual
capacity factors and for synergy with a similar California Public Utilities Commission (CPUC) resource
portfolio:
Area in CA & Resource Type
NorCal Wind
NorCal/SoCal Solar (50/50 Split)
SoCal Geothermal
% Energy
Approx. Capacity Factor
& Capacity
CF (%) Capacity (MW)
6,676
40%
1,900
5,797
22%
3,000
7,466
85%
1,000
19,940
Approx.
Energy (GWh)
33.5%
29.1%
37.4%
Total:
20-Year (2034): This case will assume a California RPS target of 40%, including appropriate DG or
other set asides.
2024 EC24-1: Remove Path 26 constraints in PC24
This expansion case will assume removal of all Path 26 constraints in the PC24 study case
2024 EC24-2: 10-Yr: Transmission expansion case based on results of E24-1
This expansion case will assume a transmission expansion in addition to the assumptions of the
EC24-1 study case. At minimum, will include IID’s STEP transmission expansion.
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Key Questions to be Answered/Addressed by the Study -This information will be used to identify data inputs required for the
study as well as key outputs that should be communicated back to the study requestor.
1. In the 10-year timeframe, how does a large increase in CA RPS (to 40%) impact transmission
utilization and congestion?
2. In the 10-year timeframe, how does a large increase in CA RPS (to 40%) affect total costs
(capital and production)?
3. In the 10-year timeframe, how will relieving Path 26 constraints affect delivery of renewable
energy within California?
4. In the 10-year timeframe, what transmission expansion will enable improved delivery of
renewable energy within California?
5. In the 20-year timeframe, what resource and transmission expansions are most cost effective
in meeting a California 40% RPS requirement?
6. In the 10- and 20-year timeframe, what reduction in CO2 emissions corresponds with meeting
a California 40% RPS requirement?
Study Case Tasks
Requestor Tasks
Responsible Party
Completion Date
1. Develop case assumptions and targets for evaluating
results in the 10- and 20-year horizons.
2. Provide transmission expansion modeling details via PG&E
EPC and/or EPCL files based on 23HS1A1 power
flow topology
3. Review & provide comments on study results and
All Requesters
report
Staff or Work Group Tasks
1. Support scoping process
2. Review scope and advise on synergistic efforts to
inform case development
3. Implement desired resource additions & transmission
additions
4. Re-evaluate Resource Adequacy, RPS compliance,
and flexibility reserves
5. Run study and report results
Responsible Party
Completion Date
WECC
SWG
WECC
WECC
WECC
Key Study Limitations -What issues will not be addressed by this TEPPC study due to limitations in time, resources, or modeling tools?
1. The 12,000 GWh of added resources are not assured delivery to any particular state or entity,
and nor are they intended to meet any one state's individual RPS requirement,
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2. The reliability impacts of the additional renewables won’t be evaluated in these studies.
Importantly, this type of resource development would take significant planning and appropriate
transmission and/or sub-transmission upgrades that were not evaluated in this study. As a
result, the additional resources will likely be added at high-voltage busses unless more specific
information is easily obtainable.
3. Incremental capacity from the additional renewable resources will likely need to be valued
based on the cost of a high capacity value resource - new combustion turbines (CT), in this
case. There are numerous combinations of high capacity resources that could be used for this
valuation, but this study only considers one.
4. The case may have to assume the capacity contribution from new renewables does not vary
with increased penetration of particular resource technologies. For example, Solar
Photovoltaic (PV) may be assumed to have a high (>50 percent) capacity contribution.
However, recent analysis suggests that the capacity contribution for Solar PV diminishes with
increasing penetration as the net load curve shifts away from periods of highest Solar PV
output.
Other Study Information – link to background material (reports/analysis completed in support of study) and or study results