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Document name

2013 Plan Summary

Category

(

) Regional reliability standard

(

) Regional criteria

(

) Policy

(

) Guideline

(

) Report or other

(

) Charter

Document date

August 15
, 2013

Adopted/approved by

Final for Board approval

Date adopted/approved


Custodian (entity
responsible for
maintenance and
upkeep)

TEPPC

Stored/filed

Physical location:

Web URL:

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(if any)

Status

(

) in effect

(

) usable,
minor formatting/editing required

(

) modification needed

(

) superseded by _____________________

(

) other _____________________________

(

) obsolete/archived)



2013 Interconnection
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2013 Interconnection
-
Wide Plan

Plan Summary


By


WECC Staff

Western
Electricity Coordinating Council

August 15, 2013




This document is for technical review purposes only. It has not been endorsed or approved by the WECC
Board of Directors


2013 Interconnection
-
wide Transmission Plan Summary

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107

Executive Summary

The 2013 Western Electricity Coordinating Council (WECC) Interconnection
-
wide Transmission
Plan (Plan) is a perspective of the Western Interconnection transmission system under a wide

variety of possible

10
-

and 20
-
year

futures. The obje
ctive of the Plan is to provide
information to
stakeholders to support their decision
-
making processes
. It is these decisions on where and
when to build new transmission
or
generation
,

or
to
take other related actions
,

that ensure the
Western Interconnecti
on is reliable, low
-
cost, efficient
,

and environmentally responsible
, while
appropriately balancing risks and opportunities.

The Plan is informational in nature and is intended to advise and guide, rather than
prescribe or
promote
.
The observations and rec
ommendations in th
e 2013 Plan reflect results
from
stakeholder
-
requested studies performed as part of the TEPPC process
. The results of these
studies

a
re

controlled by
the assumptions and data included in the transmission planning
process and models.

Furth
ermore,
WECC does not have authority or jurisdiction over: 1) the
construction of transmission lines; 2) the siting, permitting or cost allocation for transmission; or
3) the broader resource decisions that may drive transmission investment
:

therefore,
WEC
C
does not conduct transmission planning in these capacities
.


The Transmission Expansion Planning Policy Committee (TEPPC), a WECC Board of Directors
committee, guides WECC’s Transmission Expansion Planning (TEP) process used to create the
Plan.

Over the

past two years, WECC’s TEP process has
been used to
analyze
two
study
horizons
looking out
10
-

and

20
-
year
s (to 2022 and 2032)

to

form the analytical basis for the Plan.



The 10
-
year

studies

use
d

a bottom
-
up process with
load, resource and transmission
information flowing to TEPPC from other planning processes throughout the Western
Interconnection. This information
wa
s augmented by
additional
publically

available
information
,

including

stakeholder input. From this information
,

a “10
-
Year Common
Case”
wa
s created that represents an

expected


future for the
Western
Interconnection

based on recent trends and plans
. The remainder of the 10
-
year analyses
consider over
60 alternative cases that
,

to a great extent
,

reflect stakeholder input and requests, which

we
re used to assess the

utilization and
robustness of the
2022
Common Case

transmission system across a variety of alternative futures.




T
he 20
-
year
studies
use
d

a top
-
down process
.

This process start
ed

from the 2022
Common Case and then co
-
optimize
d

the
addition of resources and transmission for
each of several contrasting top
-
down scenarios depicting the future through 2032.
Unlike
the 10
-
year timeframe, which look
ed

at the performance of a specific generation and
transmission infrastructure package, the

20
-
year timeframe buil
t

generation and
transmission to meet the requirements specified by the scenario
. Each scenario
wa
s
defined by a set of key parameters or assumptions regarding fuel prices, technology
costs, environmental policies and other factors a
ppropriate for the particular future being
depicted.

This

capital expansion


shows how long
-
term generation and transmission
choices may respond to major changes in the key fundamental assumptions, without
simulating the more detailed hour
-
by
-
hour
generator dispatch and transmission flows as
in the 10
-
year studies.

2013 Interconnection
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The following are key assumptions regarding load, generation and transmission that are
germane to the observations and recommendations described in the Plan.

The Plan assumes
that:



A
ll 30

regionally

significant transmission projects identified in the Common Case
Transmission Assumptions
1

list

(modeled in the 2022 Common Case)
we
re assumed to
be completed

by 2022. These projects add roughly

3,400

miles of
345
-
kV and higher
voltage
transmiss
ion lines to the Western Interconnection.



Sufficient

generation
wa
s assumed to be added

or retired
to
meet planning reserve
margins and to
obtain full compliance with enacted
s
tate Renewable Portfolio Standards
(RPS) and Once
-
Through
-
Cooling (OTC) regulati
ons in California.



State
-
e
nacted energy efficiency (EE) and Demand
-
Side Management (DSM) programs
we
re assumed to be

fully realized.



WECC Paths and their associated limits
we
re modeled in both the 10
-

and 20
-
year
timeframes.

Key insights from the 10
-
year a
nd 20
-
year studies include the following:

10
-
Year Horizon
Observations


1.

The expected future grid, based on the existing transmission plus the Common Case
Transmission Assumptions, appears
to be
adequate
for

the Western Interconnection to
meet its load and RPS requirements over the 10
-
year
timeframe

under
2022
Common
Case assumptions.


2.

New major transmission additions could be needed under different

alternative futures.

This could occur
if substantially grea
ter renewable generation
wa
s developed beyond
the
2022
Common Case assumptions
, particularly if this development occurs in

areas
remote from load centers, such as wind resources added in Wyoming or Montana.

Closer to load centers
,

the
very large

resource a
dditions

studied for southern California
BLM resource zones

would
require major

local

transmission additions
.

TEPPC did not
study local transmission upgrades or transmission upgrades needed to meet any
resource adequacy deliverability requirements for any of
the

study cases as this type of
analysis currently lies outside the scope of TEPPC studies.



3.

Sensitivity
analysis of the 10
-
year
timeframe

for high and low natural gas prices, high
-

and low
-
hydro conditions, and high loads produced varied impacts on projected
transmission usage but did not indicate a strong requirement for major transmission
additions beyond
th
ose in the 2022
Common Case.





1

Subregional Coordination Group (SCG), “Common Case Transmission Assumptions” (2012):
http://www.wecc.biz/committees/BOD/TEPPC/External/SCG_CCTA_
Report.pdf


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4.

The 10
-
year
study

of high EE and distributed generation (DG) on
an Interconnection
-
wide basis was projected to increase transmission flows out of the Northwest as low
-
cost
generation is freed up for export to more distant h
igh
-
cost areas

such as

California.

This
potential export effect could be reduced if EE and DG measures were seen as
sufficiently dependable over the long term to allow significant reduction in otherwise
-
planned generation in an affected region.


5.

Seven res
ource option
studies

examined alternative locations and resource types for
adding 12,000 GWh of renewable generation to meet higher loads and corresponding
higher RPS requirements. These
study results

show close economic competition among
several of the ex
amined options when considering resource cost, transmission costs and
risk factors.
The
studies

identified that w
hen long
-
distance transmission costs are
considered, 12,000 GWh of Wyoming wind transmitted by a DC line to southeast
Nevada is similar in cost

to 12,000 GWh of California renewable resources. This
comparison does not include local transmission
upgrade
costs in Wyoming or California.


6.

In
the resource option analyses,
when considering projected resource investment costs
but excluding transmission cost,
t
he lowest cost alternative for adding 12,000 GWh of
additional renewable resources (in excess of what is assumed in the
2022
Common
Case) is Wyoming wind
. The variation
in resource costs between
studie
d

alternatives
is
a function of the resources selected
,

the
ir

capacity factor
s
,

and

the assumed per
-
kW
resource investment cost
.



7.

Firmed Resource Option
studies

evaluated

how different firming techniques could
improve the i
ntegration of variable generation

(VG)

and reduce the production cost
in

the
Western Interconnection. Combined cycle gas units, when added in Wyoming in
conjunction with long
-
haul DC lines
,

represented the most economic option

for this set of
studies
. Flex
ible
,

price
-
responsive

hydro and pumped storage options were also
e
xamined
.


8.

TEPPC coordinated with the WECC Planning Coordination Committee (PCC) and
Technical Advisory Subcommittee (TSS) to create a powerflow case based on a light
spring condition in the

2022 Common Case.
The specific hour of study was selected by
TEPPC stakeholders

because it featured relatively low loads
and

high output from
variable generation


a unique condition gaining interest in planning forums
.
The
subsequent reliability analysis

identified
a number of voltage concerns and branch
overloads. Planning entities are encouraged to review the contingencies that caused
these concerns when studying 10
-
year
powerflow
reliability cases that feature large
penetrations of renewable energy. Th
e full reliability analysis report is available in the
Plan appendix

materials.


20
-
Year Horizon
Observations


9.

The 20
-
year study results

contain a diversity of potential resource additions that are

strongly

driven by three

key factors:
1)
natural gas
prices
; 2)

carbon
/
greenhouse gas
penalties or prices
;

and
3)
cost improvements for key generating technologies.
Gas
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prices were the only
key factor

considered over the 10
-
year horizon
,
where they had
limited potential to impact infrastructure investment ov
er the shorter horizon
.


10.

The 2032 Reference Case is a continuation of 2022 Common Case conditions with
moderate load growth and a $37
/ton CO
2

price
. Modeling results
from

the
WECC’s new

Long
-
t
erm Planning Tool

(LTPT)

optimized resource additions based on
a
levelized cost
of energy and yielded future resource additions dominated by gas
-
fired and wind
generation.

T
he key observations from the
2032 Reference Case

include
:




Renewable resources were selected based on cost competitiveness

in addition
to their

co
mpliance with state RPS requirements
.



Levelized costs for new gas and wind resources were very close in the 20
-
year
timeframe.



Transmission additions from 2022 to 2032 were driven
by the need to gather and
deliver low
-
cost renewable resources from remote a
reas to load centers
.
Solar
penetration
appears to be
trending higher than
depicted

in the 2032 Reference
Case (and 2022 Common Case). The latest developments and expectations
,
including contracting and contract pricing,

indicate that the level of solar
penetration
is currently trending toward

exceed
ing

levels
represented

in the 2022
Common Case and the 2032 Reference Case.
New coal
-
fired generation is not
economic with a $37/ton CO
2

price.



S
ystem flexibility for balanci
ng variable
generation

(or responding to net load
changes in general) is an important concern not fully addressed by the 20
-
year
studies
.




11.

The
Scenario Planning Steering Group (
SPSG
)

created
four
WECC S
cenarios

that

were
shaped by technology innovation a
nd economic growth in the Western Interconnection.
The scenarios were:




Scenario 1: Focus on Economic Recovery



Scenario 2: Focus on Clean Energy



Scenario 3: Focus on Short
-
Term Consumer Costs



Scenario 4: Focus on Long
-
Term Societal Costs

While the four
different scenarios each included a large number of distinguishing inputs
to mold the “alternative future
,
” the key drivers among them
that

had the most significant
influence on the study case results were: natural gas prices, CO
2

costs, and technology
adv
ances for alternative generation resources.

12.

Other 20
-
year scenarios and
studies

examined a more aggressive decline in technology
costs and/or more aggressive RPS/
greenhouse gas

polic
ies

resulting in greater
dependence on model
-
selected
,

central
-
station
solar (
photovoltaic
, also
Concentrating
Solar Power
) genera
tion additions in the
Desert S
outhwest.

This drove the selection of
extensive transmission additions
in that region
.



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13.

The 20
-
Y
ear
H
igh
-
EE/DG
study

resulted in
fewer
selected (optimized) transmissi
on
additions than other 2032
studies. While this is

intuitively reasonable
, it

contrasts with
the observation th
at

certain additional transmission might be valuable under the
10
-
year

H
igh EE/DG
study
. This
difference

requires further planning assessment
. I
n addition,
further inquiry is required to understand

the tradeoff of th
is

distributed future’s potential
high per
-
MWh generation cost versus its potential for reducing stranded cost risk,
siting/construction delay
,

and environmental impact.


14.

Solar
p
enetra
tion
a
ppears to be
t
rending
h
igher than
e
nvisioned in the 2032 Reference
Case (and 2022 Common Case). The latest developments and expectations
, including
contracting and contract pricing,

now indicate that the level of solar penetration should
exceed level
s depicted in the 2022 Common Case and the 2032 Reference Case

based
on the current trend
.

Emerging Issues: Reliability, Variable Generation, Environmental Factors,
Risk

15.

R
eliability implications for peak load or other snapshot conditions have
only
been
preliminarily assessed for the 10
-
year studies
. These assessments were

based on
modeling planning reserve margins and
through
conducting path
-
breaking reliability (AC
power

flow) studies derived from production simulation results for

a

selected, likely hig
h
-
stress
,

hour.
By

contrast,
WECC’s new LTPT

was not built to perform reliability analys
e
s
on

the 20
-
year
studies

and may not be appropriate for direct use in developing deeper
reliability analyses.


16.

Operational flexibility is an increasing concern across

the Western Interconnection as
the

penetration of
VG

continues to grow
. An important modeling improvement in the 10
-
year studies
wa
s
the use
of
the National Renewable Energy Laboratory
-
derived hourly
flexible reserves tool to calculate hourly
reserve requ
irements

based on the magnitude
and statistical variability of wind and solar generation. The resulting inclusion of flexible
reserves in 10
-
year case modeling
slightly
altered overall generator commitment and
dispatch, but did not produce
a
resource short
fall or
any
large changes in transmission
flows.


17.

A simple flexibility
indicator

based on the ratio of
flexible generation (
dispatchable gas
generation

plus

15

percent

of hydro capacity
)

to variable (wind and solar) generation
illustrates potential issues associated with changes to the
future
generation mix. While
there is

enough flexibility today,
there is no way to determine

exactly where the safe limit
lies.
T
he safe limit of flexibili
ty depends on specific, detailed conditions regarding
infrastructure characteristics and operating practices, not broad indices. Furthermore,
future practices looking out to 2032 will likely provide enhanced operability and flexibility
for any given genera
tion mix.


18.

The 10
-

and 20
-
year studies incorporate environmental factors in transmission cost
characterization to a far greater degree than in past study cycles. However, it is
acknowledged
that

additional work is still being done
with
regard

to more

full
y

characteriz
ing

environmental costs
,

such as mitigation
,

associated with transmission
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projects
. T
o some exten
t, these

may also be applicable to large
,

land
-
intensive
generation projects.


19.

The 10
-

and 20
-
year studies do not explicitly capture how

risk


f
actors into

the

assessment of any particular resource and/or transmission option
,

or into
the
comparison of multiple options. Future fuel prices, environmental polices/costs and
technology advances represent key uncertainties presenting major risks and
opp
ortunities in selecting and valuing investments. This makes it essential that the wide
range
of scenarios
,
study cases and results be considered when seeking to inform
decisions.


20.

The Plan considers
three

potential hedges against uncertainty
: transmission

investment,
energy efficiency and renewable distributed generation
. Transmission investment
provides a hedge against uncertainties and risks in fuel prices, technology advancement
and environmental policy requirements and costs by making it possible to ac
cess a
wider range of resources. Energy efficiency can hedge the same kinds of risks
,

likely
with lower investment costs, stranded cost risk and environmental risk. Renewable
distributed

generation provides a similar hedge, but is subject to risks associat
ed with
uncertain technology advance
s
.


21.

Environmental siting is another important uncertainty factor having the potential to drive
up costs and delay or prevent transmission project completion.
This is a real concern for
some transmission
projects

and for

some large generation projects as well.
Future
enhanced incorporation of environmental factors in the TEPPC study methodology can
both better internalize this risk and also avoid projecting transmission additions in
to

problematic areas.

Recommendation
s

Expanding on these insights, the Plan includes the following
broad
recommendations
regarding
future
studies and how

decision

makers or others
might

use these study results as a point of
departure going forward.


Recommendation 1


Include

Uncertainty in Planning Studies

Modest
changes in
natural
gas

prices
,

CO
2

prices or penalties

and

technology costs may result
in significantly different future

optimal

generation resource mixes
,

and thus
,

different
transmission needs
. This is

especially

t
rue

beyond the

10
-
year

timeframe, which

creates both
risk and opportunity.

Due to the uncertainty
across
these three key drivers, WECC recommends
that all
applicable

planning studies

(or efforts)

include sensitivities of these

factors
.

Recommendation 2


E
valuate
Options to Hedge
against

Future
Uncertainty

Decision makers may want to investigate
strategies

tha
t

can protect against the inherent risk
posed by the uncertainty associated with
gas prices, CO
2

and other environmental costs or
constraints, and tec
hnology advances. Three important categories of hedging strategies include
transmission investment, demand
-
side measures (efficiency and demand response), and
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distributed renewable generation.

Based on results observed in TEPPC studies, WECC
recommends that energy efficiency/demand response
/distributed generation

programs
and
transmission expansion be evaluated as potential hedges against the uncertainty posed by gas
pricing, CO
2

costs and tech
nology costs.

Furthermore, hedging against uncertainty and delay for
siting large projects may be addressed by
securing and maintaining permits for large
interregional transmission projects,

by
gaining better information regarding transmission siting
obsta
cles
and identifying d
esirable
transmission
corridors,
and

by appropriate incorporation of
“distributed” (EE and DG) strategies
.

Recommendation 3


Assess
Future
Operational Flexibility

Both 10
-

and 20
-
year studies suggest that peak
-
demand growth will be
m
odest
and there will be
adequate resources to serve peak

demand. However, the increase in
VG

during the same
time
frames

highlights the need for flexible resources
, or other sources of operational flexibility
.
WECC recommends that planners and others attemp
t to develop more comprehensive,
accurate and detailed assessments of flexibility
needs

and of operational and infrastructure
investment approaches to providing flexibility.
This includes developing practical methods for
measuring the flexibility implicati
ons of alternative infrastructure investment strategies and for
determining where the flexibility risk threshold lies. It also includes giving adequate
consideration to
the
benefits of geographic diversity of variable resources, as well as efficient
operat
ional and investment strategies to utilize this diversity. A forward
-
looking assessment
should consider not only conventional sources of flexibility

(e.g.
,

gas combustion turbines)

but
also less conventional sources
such as

market and operational reforms,
demand
-
side measures
and non
-
conventional storage.

Recommendation 4


Evaluate Risks in
Gas
-
Electric Interface

Recent progress has been made in evaluating the gas
-
electric interface and the risk to reliability
it
may
pose for the Western Interconnection. Many of these studies have created the framework
for
additional analysis that is needed to quantify the risks and vulnerabilities faced by the bulk
power system regarding this issue.
WECC

recommend
s

that TEPPC perform
such a study
during one of its

upcoming study cycle
s
.

T
he study
should

build upon current Western Gas
-
Electric
I
nterface study efforts, such as the SPSC study currently under way.
The specific scope
and goal of the study will be defined by TEPPC

at a later

date
.

Recommendation 5


Further Quantify Uncertainty

Many observations and recommendations in the 2013 Plan are related to future uncertainty with
regard to gas prices, technology costs, carbon prices and even transmission assumptions in
datasets.
Other

key uncertainties involve environmental siting costs and hurdles, and the
minimum threshold requirements (and costs) for system flexibility, especially for scenarios
having high wind/solar penetration.
WECC
recommend
s

that TEPPC

and other planners

attempt

to further quantify

or bound these key uncertainties

and provide that information to
stakeholders for external use.


Recommendation 6


Attempt to Quantify Mitigation Costs

Compensatory mitigation costs are one
tool for

rectifying adverse environmental ef
fects of
building new transmission

after avoiding and minimizing effects to the extent possible
. WECC
recommends that TEPPC

consider the

use

of

analytical results from ongoing Environmental
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Data Task Force (EDTF) work
. These results may

guide discussions a
nd decisions as TEPPC
considers

the use of mitigation costs as a component of transmission capital costs

(and for
selecting optimal corridors)

when creating transmission expansion plans.

This feeds into
the
assessment and management of risks associated with environmental siting
, as previously
mentioned.

Recommendation
7



Identify Environmentally Least
-
Risk

Corridors

WECC has used th
e new

LTPT to optimally derive feasible network expansions necessary to
meet
the load and generation requirements of future scenario study cases

in the 20
-
year
timeframe
.

To date, corridor identification has been limited to these electrical network
expansions.

However, one of the strengths of the
LTPT
is its ability to

take into co
nsideration
environmental costs and risks
in
identifying
corridors

that are
considered to be
least
-
risk paths
based on environmental data.

WECC

recommend
s

that TEPPC consider using the LTPT to
derive least
-
risk corridors between major load and generation h
ubs within the Western
Interconnection, and provide the results of this analysis to stakeholders.

These corridors could
be identified regardless of LTPT
-
derived network expansion
s.

The corridors connecting key
resource and load hubs

could be provided to pr
oject developers for more detailed analysis.

Recommendation 8


Consider Improvements

to Modeling, Data Quality
and Data Sharing

TEPPC has made a number of improvements to its process
es

and analytical capabilities since
the first WECC 10
-
Year Plan
was
rel
eased in 2011. However, even with these improvements
,

the need to improve planning analyses still remains.

Stakeholders have provided many
suggestions for ways that modeling might be improved based on results produced in the current
TEPPC Study Cycle. WECC

recommends that TEPPC undertake
the
work to improve a number
of technical modeling issues, including investigating improvements to the 20
-
year LTPT
Modeling approach.

TEPPC should also embrace the opportunity to improve data quality and
sharing practices.

Many other planning processes rely on TEPPC data. One way for TEPPC to
provide value to the Interconnection is for this public data to be of high quality and readily
available for stakeholder consumption.

Recommendation 9


Acknowledge
Uncertainty
around

A
ssumed
T
ransmission

In both the 10
-

and 20
-
year studies, transmission additions identified as Common Case
Transmission Assumptions
we
re assumed built and included in the model.
These projects are at
various stages of development with varying degrees of
certainty that they will be constructed.

T
o
account
for
the possibility that one or more of these projects are not constructed,
WECC

recommend
s

that TEPPC consider performing sensitivities

by individually removing key projects
from the
2022
Common Case
.
WE
CC

also recommend
s

that others using the TEPPC dataset
consider this sensitivity.

Conclusion

Aside from recommendations

and insights discussed in this Executive Summary
, the Plan

is a
compilation of

documents that
provide a wider and more extensive range o
f

specific study
observations resulting from the 10
-

and 20
-
year analyses
, many of which are discussed in the
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wide Transmission Plan Summary

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107

Plan Summary
. These observations represent significant plan findings that are technically
robust, but did not result in a specific recommendation

or overarching insight
.

The Plan

represents the continuing progression of WECC’s planning activities

and is
the result
of a coalescence of broad stakeholder input, WECC’s technical capabilities, technical support of
numerous organizations, and adequate fi
nancial resources.
WECC will continue to work with
stakeholders to improve the overall quality of the planning process, including the challenges of
emerging issues of reliability,
VG

and risk (Observation 14 and 15).

WECC further commits to
working with st
akeholders to consider potential changes to the planning process to ensure that
future plans have the greatest potential value.

The Plan’s
limited ability to delve into greater
depth or produce more precise conclusions
,

in part
,

reflect the vast breadth an
d diversity of the
W
estern
I
nterconnection and its constituents, the need to use publically

available data, limits
(and finite speed of refinement) of modeling capabilities, and necessary limited granularity of the
analyses performed.

WECC would like to ex
press its sincere appreciation to the many individuals and organizations
that have contributed to the Plan. The volunteers who comprised the TEPPC committees and
work

groups
were

instrumental
in assuring that the best information was made available,
comprehensive analysis was performed, and thorough review was conducted. Looking forward,
WECC has a robust base from which to continue advancing the quality of planning products for
the Western Int
erconnection.



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Contents

Executive Summary

................................
................................
................................
...................

4

Contents

................................
................................
................................
................................
...
13

Preface

................................
................................
................................
................................
.....
14

Acknowledgements

................................
................................
................................
...................
15

Introduction

................................
................................
................................
...............................
16

Planning Approac
h and Methodology

................................
................................
........................
24

Tools and Models

................................
................................
................................
.................
25

Data and Assumptions

................................
................................
................................
.........
26

Environmental and Cultural Considerations

................................
................................
..........
29

Costs

................................
................................
................................
................................
....
31

Operational and
Commercial Assumptions

................................
................................
...........
32

Other Assumptions

................................
................................
................................
...............
33

Observations

................................
................................
................................
.............................
34

10
-
Year Studies: Methods, Results, and Observations

................................
.........................
35

20
-
Year Studies: Methods, Results, and Observations

................................
.........................
60

Recommendations

................................
................................
................................
....................
89

Conclusion

................................
................................
................................
..............................

100

Glossary
................................
................................
................................
................................
..

101



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Preface

E
lectric energy serves as
one of
the foundation
s

of modern society.
Ensuring that electricity is
available to everyone at the time it is needed is

a multi
-
faceted challenge. One
such
facet is to
ensure that there is sufficient
infrastructure
(
e.g.
,
transmission, distribution, generation
, demand
-
side capabilities
)
to serve
not only current needs
;

but also
future consumer needs reliabl
y
,
economic
ally

and environmentally responsibl
y
.

The t
ransmission

grid

is the connection between generation and load. It
requires many
years to
build,
involves significant capital costs
, impacts the
environment
, and determines
which
generation options
may
be
made
availa
ble to meet
consumer

needs. Because of this
,

transmission must be
planned diligently

and with sufficient lead time
, taking into
consideration
a
range of futures that may unfold looking out 10,

20 or more years
.

Transmission is proposed and constructed for

many different reasons. Some are reliability
-
based
,

such as ensuring sufficient capacity into major load centers as the population
,

and
thus
load
,

increase
s
.
O
thers are driven more by economics
,

such as accessing less expensive
generation or enabling powe
r sales between utilities.
Transmission may also be proposed and
constructed to meet policy directives such as state Renewable Portfolio Standards (RPS).

I
n the
end, transmission that has been built
in the past has provided both
a
reliability and economic
value.

The Western Electricity Coordinating Council’s (WECC) t
ransmission planning activities serve to
understand the future needs of the transmission system

in the Western Interconnection
. The
wide ranges of climate, consumer demographics,
regulatory constructs
and distances between
loads and resources require division as well as coordination among the
multitude of
planning
duties.
Thus,
planning activities

in the Western Interconnection
are divided by
both
geographic
reach and planning

time

horizons.

Transmission
E
xpansion
P
lanning (TEP)
at WECC
is part of a suite of planning activities

that
support WECC’s mission

to promote and foster a reliable and efficient Bulk Electric System.


This is accomplished through state
-
of
-
the
-
art analysis gu
ided by robust stakeholder
-
driven
processes led by the Transmission Expansion Planning Policy Committee (TEPPC).
The work is
funded through a combination of retail Load
-
Serving Entity

(LSE)

assessments
2

and a grant
from the U.S. Department of Energy throug
h 2014.

Through an open, stakeholder
-
driven process, the products and processes created under
TEPPC provide credible information on the future of the electric energy infrastructure needs and
support decision
-
making processes throughout the Western Intercon
nection and nationally.
Transmission expansion planning stakeholders cover the breadth of organizations and
individuals that impact, influence and are interested in the future of electric energy in the
Western Interconnection, including:



Consumer Advocates




State and Provincial Officials




2

Section 215 funding

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Transmission Owners, Operators, and Developers



Generator Owners, Operators, and Developers



Load
-
Serving Entities



Subregional Planning Groups



Environmental Advocates



Technology Advocates



Tribal Representatives

Because of this breadth, stakeholders value different products and processes that are provided
under TEPPC.
For example, t
he public policy, regulatory, state and non
-
governmental
organizations value the independent and state
-
vetted analyses and recommendat
ions contained
in the Plan and other documents.
By

contrast, the generation and transmission planning
communit
ies

value the stakeholder
-
vetted data and models they can use in their respective
activities
, as well as the

value
of
the common foundations of le
arning created by discussing
pertinent energy issues that will impact how a robust transmission grid will be maintained in the
future.

TEPPC products and processes are also used by some planning entities to help fulfill their
planning coordination requirem
ents under FERC Order 890.
T
h
ese

activit
ies

will also serve to
meet some entities’

regional compliance

requirements under
FERC Order 1000
.

As the complexity of the questions posed by stakeholders has increased, TEPPC has grown its
analytic capability, brea
dth of analysis
,

and stakeholder processes. Currently, TEPPC performs
four functions:



M
aintains a public database of planning data and models;



F
acilitates an Interconnection
-
wide expansion planning process;



P
erform
s

economic analysis of the Western Interc
onnection; and



P
repare
s

Interconnection
-
wide transmission plans.

The
2013 Interconnection
-
wide Transmission Plan

Summary

(this document) provides a
synopsis of WECC’s message to

stakeholders in

the Western Interconnection
of the
work
completed by TEPPC du
ring the most recent biennial planning cycle. It is written to be
understood by audiences that are familiar with the electric power industry and written with
sufficient detail that further reading is not necessary for most audiences.

Acknowledgements

WECC
would like to express its sincere appreciation to the many individuals and organizations
that have contributed to the Plan. The volunteers who comprised the various committees and
work

groups
, shown in
Figure
1
,

were

fundamental in assuring that the best information was
made available, comprehensive analysis was performed, and broad review was conducted. A
2013 Interconnection
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complete list of organizations and persons
involved in creating the Plan is found on the
Plan
webpage
.
3


Figure
1
: TEPPC Organizational Structure

TEPPC
Chair


John Cupparo
Vice chair


Mike Evans
Staff liaison


Keegan Moyer
EDTF
Chair
-
Carl Zichella
Staff liaison
-

Byron
Woertz
SWG
Chair
-

Tom Carr
Staff liaison
-
Ben
Brownlee
MWG
Chair
-
Tom Miller
Staff liaison
-
Stan
Holland
DWG
Chair
-
Jamie Austin
Staff liaison
-
Stan Holland
MDTF
Chair
-
Carl Linvill
Staff liaison
-
Byron
Woertz
TAS
Chair
-
Jim Filippi
,
Vice chair
-
Tom Miller
Staff liaison
-
Ben Brownlee
SPSG
Chair
-
Gary Graham
,
Vice chair
-
Jim Feider
Staff liaison
-
Byron Woertz
SCG
Chair
-
Susan Henderson

Vice chair
-
Rich Bayless
Staff liaison
-
Keegan Moyer
HMTF
Chair
-
Tom Chisholm
Staff liaison
-
Ben
Brownlee
DSMTF
Chair
-
Liang Huang
Staff liaison
-
Dan
Beckstead
PDTF
Chair
-
Howard Schwartz
Staff liaison
-
Byron
Woertz

Introduction

The
2013
WECC Interconnection
-
wide Transmission Plan (Plan) is a perspective

on the

transmission system

within the Western Interconnection

under a wide

variety of possible
futures
.
The objective of the Plan is to provide
information
based on this perspective
to
stakeholders
to support

their decision
-
making processes
. It is these decision
s regarding where
and when to build new transmission

and

generation or take other related actions that ensure the
Western Interconnection is reliable, low
-
cost, efficient
,

and environmentally
responsible
.

TEPPC, a
Western Electricity Coordinating Council (
W
ECC
)

Board
of Directors
committee,
guides WECC’s

Tr
ansmission Expansion Planning

process used to create the Plan.
The
TEP
process used to identify
potential
planning needs in a 10
-

and 20
-
year timeframe

i
s

described in
the
TEPPC Planning Protocol
.
4


The 1
0
-
year
timeframe uses

a bottom
-
up process with information flowing to TEPPC

from other
planning processes

throughout the Western Interconnection
. This information is augmented by



3

Plan webpage located on the WECC website:
http://www.wecc.biz/committees/BOD/TEPPC/Pages/2013_Plans.aspx


4

TEPPC Planning Protocol:
http://www.wecc.biz/committees/BOD/TEPPC/External/TEPPC_PlanningProtocol.pdf


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other publically

available information based on stakeholder input.

From this
information a “10
-
year Common Case” is created
that

represents an expected future. The remainder of the 10
-
year analyses focus on understanding the

robustness of the Common Case, the

impact of
various alternative futures
,

as well as
other studies requested

through the

TEPPC
study request
process.

The 20
-
year timeframe
, alternatively,

uses a top
-
down process using

a

scenario planning
approach. Unlike the 10
-
year timeframe, which looks at the performance of specifi
ed

generation
and transmission infrastructure

package
s
, the 20
-
year timeframe builds generation and
transmission to meet the requirements specified by
each
scenario. Th
is

capital expansion
approach serves to draw clear connections
regarding how
energy
policies
, technology cost
s
,

environmental drivers
, and economic growth impact

generation and transmission

infrastructure

choices.

In addition to the two
forward
-
looking analyses
, TEPPC also performed a “back cast” analysis of
2010 actual operating conditions. The purpose of th
at

analysis was to
: 1)

compa
re

model
performance
versus

actual operations
; 2)

better understand, quantify and improve upon
modeling limitations
;

and
3)
identify opportunities to better represent the effects of commercial
arrangements and operating practices without using confidential

information.


The Plan represents the continuing evolution of WECC’s planning activities.

The Plan’s
strengths are the result of a coalescence of broad stakeholder input, WECC’s technical
capabilities, technical support of
numerous
organizations, and
adequate financial resources.

The Plan’s limitations are
a result of the vast analysis footprint, use of publically

available data,
modeling capabilities
, and level of detail of the analyses performed.

Looking forward, WECC
has a robust base from which to
continue advancing the quality of planning products for the
Western Interconnection.


Improvements since 2011

In 2011, WECC published its first
-
ever 10
-
Year Regional Transmission Plan. After publication,
WECC reached

out to stakeholders and other consumers

to ascertain the usefulness of the
information provided and what additional information would be valuable. In addition, the 2011
Plan identified a number of gaps that resulted in a set of recommendations for the subsequent
planning cycle.

The combination
of this feedback, coupled with the growth of WECC’s technical
capabilities, has yielded a number of improvements to the data, models, analyses and results in
the 2013 Plan. Key improvements include:



Environmental considerations


In both the 10
-

and 20
-
yea
r analyses, transmission
capital cost calculations
used

the environmental risk categorization created by the
Environmental Data Task Force (EDTF). This important addition enabled transmission
costs to better reflect the costs involved in avoiding sensitive

habitats.




Water


The 2011 Plan directed WECC to “refine and improve the analysis of water
withdrawal for electricity generation in transmission planning studies.
” WECC has
completed this task by including the capability to reflect water constraints in
its LTPT.
Sandia National Laboratories provided the water data for this modeling.


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Capital costs


The capital cost calculation methodology and data, identified as a
limitation in the
2011 Plan
, have been
fully
redesigned. Transmission line capital costs
a
re now Geographic Information System (GIS)
-
based to
better
enable a sufficient
understanding of the real
-
world land use and environmental considerations that impact
actual transmission costs. Generation capital cost calculations were also revisited. The
ty
pes of generation were expanded and the components that comprise the costs were
updated.




Variable generation (VG) considerations


The impact of VG was investigated
through
the analysis of operating reserves (beyond already
-
modeled contingency and regulat
ing
reserves) held to balance variability hourly in each of several regions.. TEPPC calls
these reserves
“flexibility reserves
.”

In addition, the ratio of
flexible generation

to
VG

was
compared among

20
-
year cases, the
2022

Common Case and present conditio
ns
;

as a
very preliminary indicator of the need to look more deeply at system flexibility issues.




Reliability analysis


The Plan includes a discussion of resource adequacy, transmission
reliability and VG concerns
.

Preliminary (but path
-
breaking) reliability analys
e
s of high
-
stress hours in the 20
22

Common Case are informative but do not supplant

local,
regional and project
-
driven reliability analyses necessary to ensure the “as
-
built” future
system is reliable and
compliant with
North American Electric Reliability Corporation
(
NERC
)

Reliability Standards.



Common Case Transmission Assumptions

(CCTA)



The CCTA lists a set of major
transmission additions that are expected to be in
-
service in 2022.
The list, shown in
Figure
17
,

was created by the Subregional Coordination Group (SCG) using a set of
objective, consistent and transparent metrics regarding project devel
opment status and
financial support.
In doing so, the
SCG

developed a list of questions regarding proposed
transmission projects that help to better understand the project purpose and other
parameters at different stages of transmission project development
.



Stress testing


The 2022 Common Case was tested against a large number of
alternative 10
-
year futures regarding renewable generation and other developments to
examine how the “expected” (Common Case) transmission performed across those
different
futures.



E
conomic analysis of resource option c
ases and transmission expansion


WECC

expanded the breadth of the 10
-
year resource and transmission capital cost analysis to
include an increased number of states and regions that cover nearly the entire foot
print
of the

Western

Interconnection.




Historical path data


Since the 2011 Plan,
historical path
data for 2010 and 2009 has
been

compiled

and posted to the WECC website.




Cost of cycling


WECC was
able to procure generation cycling

costs, but all
production
cost model (
PCM
)

tools available at the time of
the
study were no
t able to incorporate
cost

of cycling

penalties

into their model. Since that time, WECC has worked with
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vendors to allow for the consideration of cycling costs.

These costs will be

included in
future
TEPPC
study cycles.




DC
l
ine
m
odeling


WECC coordinated with vendors to update the DC line model in the
PCM. However, results have shown that room for improvement remains.

Intended Uses

The Plan is informational. It has been designed
specifically to provide high
-
quality, stakeholder
-
driven
,

integrated analysis using consistent data and processes that reflect
enacted energy
policy mandates
.
5

Importantly,
WECC does not have authority or jurisdiction over: 1) the
construction of transmiss
ion lines; 2) the siting, permitting or cost allocation for transmission; or
3) the broader resource decisions that may drive transmission investment.


The Plan provides information on an expected f
uture Western
Interconnection in

2022
and
offers
a number
of insights regarding
the robustness of transmission in the expect
ed

future and
potential
transmission
expansion
needs

under a variety of alternative futures.

The
Plan
also looks at
exten
ding

the
expected future
by
an additional 10 year
s

to 2032. This 20
-
year timeframe take
s

a scenario planning approach that looks at the impacts of
fundamentally
plausible futures for the Western Interconnection and how their
various
policy, technology
advance
ment
, economic and other factors may affect ele
ctric resource deployments and
transmission requirements.

The intended use of information contained in the Plan and
related material is

further
described
for various

specific

stakeholder groups.

Energy Policymakers

The Plan provides information on the
pote
ntial
impacts of implementing
current and future
energy policy decisions.
It

includes an analysis that compares the
impact
of such policy
decisions
on
the
value of, and requirements for,
transmission of

various

renewable energy
procurement and other policy

directives
.

Furthermore,
the
Plan analyses demonstrate

how
cost
s

associated with
energy
-
related

policies

could
affect the overall
cost of energy.

In addition, the
Plan illustrates areas where different types of generation, including renewable, may be located
when
taking

into account the transmission that could be used
, or would be needed,

to deliver
that generation to major load centers in the
West
ern
Interconnection. This information can be
used by state, provincial and federal policymakers to
inform and
support future energy policy
decisions.

Utility Industry Regulators

The Plan shows the potential regional impacts of what are mostly state
-

and p
rovincial
-
approved
energy infrastructure decisions and what additional infrastructure may still be required in the 10
-
year timeframe

under certain scenarios
.
It

highlights

the role of

transmission projects assumed
constructed in the
2022 Common Case
, many
of which
are currently
under
regulatory
review
.



5

Requirements include state and provincial renewable mandates (e.g., Renewable Portfol
io Standards)
and once
-
through
-
cooling retirements known at the time the analysis was conducted.

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The Plan also demonstrates the robustness of the expected transmission network in 2022
against a number of plausible alternative futures.

The Plan
highlights transmission
paths that, even with the assumed tra
nsmission additions, still
appear to be highly
used

or congested

in 2022 and how they
trend in

the following 10 years.

Utility Industry Procurement Decision
-
makers

The Plan provides a
n Interconnection
-
wide

perspective of known
generation and transmission
procurement decisions.
The Common Case represents generation and transmission that are
assumed to be constructed by 2022.

Subsequent
observations and recommendations in the
Plan are dependent upon the assumption of these elements in the
2022
Common Case
;

i
f the
assumed generation and transmission are

not constructed
, it

will impact
O
bservations and
R
ecommendations in the Plan.

Industry procurement decision

makers should consider the
observations and

recommendations
provided in the Plan
in
their future
decisions on procurement and planning coordination.

In
addition, the models and datasets created during the planning process are available for use in
respective planning processes.

Limitations

Observations and recommendations reported in the Plan are based

on the analysis completed
as part of the
2011
-
2012
TEPPC Study Program
, other WECC activities
,

and analys
e
s
conducted by others in support of TEPPC.
The data and modeling assumptions used
in the
analysis

were developed using a collaborative stakeholder pr
ocess

and publically

available
information
. They reflect stakeholder consensus on available information regarding energy
policies, load forecasts, transmission project
statuses

and resource procurement trends at the
time
the analys
e
s w
ere

performed
.

The d
ata and assumptions used in the studies were based on public information. This increased
the transparency of the planning process and results
,
and

limited the level of detail that could be
incorporated into studies. WECC did not use confidential data such
as current or future
procurement contracts, bilateral agreements
, transmission rights

or other commercially sensitive
information.

The
10
-
year studies use

a PCM as
the

primary
analysis

tool. The PCM simulate
s

the hourly
operation of the entire Western Interconnection for the study year and provide
s

important
information about the utilization of generation and transmission. The PCM is useful for
evaluating
generator operation and transmission flows as impacted
by potential transmission
additions and by constraints on generator operation. It does not evaluate capital costs
,
transmission reliability or sub
-
hourly operational impacts. Additionally,
TEPPC’s model
does not
recognize the
effects
of ownership or contractual rights on a generator’s ability to access
transmission. Of particular concern, the increasing amount of
VG

analyzed in the 10
-
year
planning studies indicate the need for sub
-
hourly

operational
and stability analyses
,

and other
e
valuations outside the capacity of the
hourly
PCM.

An investigation into how DC lines are modeled indicate
d

that the

WECC

PCM tends to favor
loading AC lines prior to DC lines. This is due to the different algorithms used for calculating and
applying trans
mission losses for DC lines, as described in the

2022 Common Case report
.
T
his
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issue
may have
resulted in the
low utilization
of the

existing

DC lines modeled in the 10
-
year
planning studies and may have caused congestion on the AC system
located
near the
DC lines
to be overstated. As a result, it is difficult for the PCM to fully value the benefits of a two
-
terminal
DC line. This issue is exacerbated when evaluating a three
-
terminal DC line.
However, in
resource and transmission expansion studies, it is co
mmon practice
with
in TEPPC studies to
explicitly match

generation output to DC
-
line flow, thus alleviating some of the DC

line

modeling
issues. This type of modeling is consistent with DC line operation in reality as their flows are
able to
be
physically
s
cheduled.

The

PCM may

also

be undervaluing arbitrage opportunities
posed by long DC lines.

Given the limitations of the DC line modeling, WECC will continue to
work with software vendors to improve the model performance in the upcoming study cycle.

While
hourly
PCM

provides useful information about hourly transmission congestion and
utilization, this information alone is not sufficient to drive new investment. The Western
Interconnection has a decentralized market and transmission ownership structure. Majo
r new
transmission investment

of interconnection
-
wide importance

is likely to be driven by the LSE
’s

desire
s

to access renewable generation resources with a high
-
degree of delivery assurance,
which
, besides sufficient physical transmission infrastructure,

requires firm, long
-
term
transmission contracts

or else a market design (
e.g.,
California ISO footprint) making sufficient
transmission capacity available on a non
-
contractual (
i.e.
, scheduling and bid
-
based) basis
.

The 20
-
year studies use WECC’s new LTPT
, the
vision

for which was

to create a capital
expansion modeling tool for use in long
-
term planning. During this

initial

study cycle, a “proof
-
of
-
concept”
approach

was taken with the

LTPT

to evaluate its

useful
ness

as an
addition to the
suite of tools cur
rently used in long
-
term planning. While the “proof
-
of
-
concept” for the LTPT
was

the focus of the initial study cycle
, there are areas for improvement with the LTPT that have
been identified through stakeholder and staff review. As with any new software to
ol with this
level of complexity, a period of maturity is needed before
robust study
results can be expected.

Cost comparisons of different renewable resources and potential transmission additions are an
important part of the analyses and results described

in the Plan. The comparisons were based
on capital cost estimates for different renewable resources and the transmission projects
needed to access those resources. The capital cost estimates reflect generic characterizations
of renewable technologies and
transmission projects.

Summary cost information in the Plan
does not fully demonstrate rate payer impact of different resource futures. Rate payer impact
comparisons require operating cost as well as capital cost information.
They also require
assumptions
about how contract prices reflect resource capital costs (e.g., cost recovery period)
and transmission costs as well as about the market value of the renewable generation to the
receiving load areas.
While the 10
-
year studies produce variable or operationa
l cost results, this
information is not
explicitly
produced for the 20
-
year cases.

Just as the capital cost comparisons reflect generic characterizations or renewable
technologies, the
categories of
resource additions
are
themselves generic and rely on ver
y
basic selection methodologies and stakeholder
-
approved tools.
Several 10
-
year studies
examined a variety of further resource additions in different parts of the West, beyond the
Common Case resource level, along with transmission additions to support the

resource
additions. It was not possible within the overall study program with numerous study cases to co
-
optimize each assumed resource addition with each particular transmission solution being
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tested. For this reason, some of the discrete transmission ad
ditions examined may display
lower
-
than
-
optimal annual utilization in the production simulations.


As discussed earlier, a number of
potential
areas for improvement were identified in the 2011
Plan

and follow
-
up work
. Some of the i
mprovements

are captured
in
Figure
2
, which
was
included in the
2011 Plan.
TEPPC stakeholders identified and described many of these potential
improvements in the
10
-
Year Plan Follow
-
Up Report
, which is available in the 2013 Pla
n
appendix materials. TEPPC has made s
ignificant progress on some of the i
mprovements
identified in the Follow
-
Up Report. S
ome of the i
mprovements

have
yet to be
addressed
fully.
For example, TEPPC has not decided
how and to what extent TEPPC’s west
-
wide s
tudies
should address
local

transmission additions that may
be needed to integrate new remote or
local generation resources.
It is expected that c
omparisons of different resource

and
transmission

alternatives

may change as improvements are made
.
TEPPC will

undertake
follow
-
up efforts to explore potential areas for improvement identified in the 2013 Plan.

Figure
2
: Figure 12 from 2011 Plan Summary


Plan
Organization

The organization of the 2013 Plan leverages the best practices an
d lessons learned from
previous TEPPC and other
planning processes
. This approach creates product consistency
over time and assures the Plan has leveraged the learning model under which TEPPC
operates.

The Plan is voluminous. There are
almost

1,
200

pages
of WECC
-
authored material, plus
appendices covering the numerous technical topics that have contributed to the Plan
2013 Interconnection
-
wide Transmission Plan Summary

Page
23

of
107

development. This fact, coupled with the breadth of the Plan’s audience, necessitates that the
information in the Plan be separated into maj
or sections. This enables audience segmentation
and electronic files that can be downloaded and viewed reasonably.

The Plan
is
published electronically in the sections described below. In addition, there will be a
number of printed publications
prepared f
or various levels of technical
depth
.

Plan
-
related
d
ocuments, datasets, tools

and presentations are available

on the
Plan webpage
.
6

Figure 2
shows the 2013 Plan Organization.

Figure
3
: 2013 Plan Organization



The Plan Summary (t
his document)
provides

a synopsis of WECC’s message to the Western
Interconnection. It is written to be understood by audiences that are familiar with the electric
power industry and written with sufficient detail that further reading
of more in
-
depth docu
ments
is not necessary for most audiences.

The Background and Context section is designed to give readers
,

at all levels
,

an
u
nderstanding
of

why the Plan
wa
s created,
the value it is intended to bring to stakeholders and readers
generally
, and the
process

by which it
wa
s created. It sets the tone for the rest of the document
and heavily levera
ge
s

past documents created by the TEP program
.

The
Data and Assumptions

section
of this report
is a detailed explanation of the sources of data
and assumptions used in the Plan. The purpose is to describe the
origin and processing

of
information used in the Plan
analyses. In addition to presenting a foundation for credibility, this
section provides others who wish to use t
he

data in their work with the information necessary to
defend its use.

The
Tools and Models

section
in this report
describes the various tools and models used in the
Plan analyses. In addition to providing readers with the details on how data
wa
s
computationally
turned into results, this sect
ion also creates the technical justification for others’ use of these
tools and models.




6

Plan webpage on the WECC website:
http://www.wecc.biz/committees/BOD/TEPPC/Pa
ges/2013_Plans.aspx


Background and Context

Data and Assumptions

10
-
Year Horizon

20
-
Year Horizon

Plan Summary

Tools and
Models

WECC Path
Reports

Appendices

2013 Interconnection
-
wide Transmission Plan Summary

Page
24

of
107

The

fourteen

10
-
Year
s
tudy
reports

contain the detailed study report for each study conducted
in the 2011 and 2012 TEPPC Study Programs.
These reports are

designed for

technical
audiences

looking for specifics on a particular study case. This section is used to fulfill the
obligations to study requestors as described in the TEPPC Planning Protocol.

The
ten
20
-
Year
study
reports

contain the detailed study report for the
long
-
term planning
scenarios and other studies completed as part of the 2012 TEPPC Study Program. The section
is designed for those interested in further detail on the 20
-
year studies. Importantly
,

and in
contrast to the 10
-
Year
study
reports
, the expected

audience is broader

in that the 20
-
year
studies address a wider range of policy, economic and technological futures, but on a more
general level
. Thus, the language
has been

crafted to be understood not only by
technical
audiences

but also by those
who
may be less technically
-
oriented
.

The WECC Path Reports provide a summary of Plan results for 25 major
transmission
paths

that are tracked by the TEP program
. In addition, this section contains the regular update of the
historical path utilization

analysi
s
.

The appendices
consist of

individual, in
-
depth
documents
related to the

specific activities under
the TEP program

that
were

used as technical support for the Plan:



Cost of
C
ycling
r
eport
7



Recommendations for Minimizing Environmental Risks of
Transmission



Capital
C
ost report


G
eneration and
T
ransmission



Sandia National Labs
W
ater
r
eport
8



Demand
-
side
R
esource

and Energy Efficiency

report



TEPPC Common Case
Reliability
A
nalysis report



Integration of Variable Generation report

Planning Approach an
d
Methodology


The Plan weaves together
extensive electric system load/resource/transmission data, important
current and potential future energy
-
related policies, technology and technology advance
characterizations
, and robust analytical methods to provide

a cohesive story about transmission

utilization and

expansion in the Western Interconnection.
TEPPC operates under a “learning
model” where lessons learned from the previous study cycle and other efforts are incorporated
into subsequent cycles.

This has r
esulted in
many technical improvements
. In addition
,

the
lessons learned have spurred
increasing focus on identifying
which

drivers influence key results,
including commonalties among otherwise
-
different cases having similar key drivers and/or



7
Aptech, “
Power Plant Cycling Costs
” (2012):
http://www.wecc.biz/committees/BOD/TEPPC/NonWECC%20Documents/A
ptech_Power_Plant_Cycling_
Cost
-
Lower_Bound.pdf


8

Sandia National Labs, “
Water as a Constraint for New Thermoelectric Generation in the WECC
” (2012):
http://www.wecc.biz/committees/BOD/TEPPC/NonWECC%20Documents/Sandia_WaterUsage_Transmis
sionPlanning.pdf

2013 Interconnection
-
wide Transmission Plan Summary

Page
25

of
107

similar tran
smission consequences
.
For each study performed
,

a “study scoping form”
is used

that

includes
the major
study assumptions
;

central question(s) being pursued
;

and
,

in some
instances
,

the expected outcomes
. This information provides context and enable
s

bette
r
comparison between studies to be
performed
.

Tools and Models

The biennial TEPPC study cycle requires WECC staff and stakeholders to develop tools,
models and datasets that describe two study horizons, 10
-
year and 20
-
year.
The models and
data used for the

two timeframes are diverse and

yet

complementary. One serves to understand
the performance of infrastructure choices while the other the drivers of infrastructure choices.
The 10
-
year study horizon
(year 2022)
was performed in a
p
roduction
c
ost
m
odel (PCM
)
,

while
the 20
-
year study horizon
(year 2032)
was analyzed in a capital expansion model (LTPT).


The PCM simulates the operation of the power system given a discrete set of
assumed (input)
load, generation and transmission. It performs a security
-
constrained economic dispatch
(SCED)
of the electric system for
every hour

of the study year
.

The SCED minimizes the

total
operating costs of the Western Interconnection

while ensuring that transmis
sion flows and
resource dispatch are with
in

system
capabilities and
adhere to established reliability standards
and practices, including
limitations due to nomograms, path loading restrictions, and contractual
obligations
. Model results on operational cost
s and transmission utilization and congestion were
used to help TEPPC evaluate the electric system in the 10
-
year study horizon.

The LTPT, WECC’s newest planning model, is a capital expansion optimization tool. The LTPT
is comprised of the Study Case Devel
opment Tool (SCDT) and the Network Expansion Tool
(NXT) that work together to co
-
optimize generation and transmission expansions necessary to
meet load at least
-
cost

on a seasonal basis over all four seasons

given a set of stakeholder
-
derived decision fact
ors (e.g., environmental, policy, economic, reliability) and reliability
-
based
constraints.


A key difference between the two mode
ls is that the

PCM optimizes the
hourly
dispatch of
generation
resources
, while the LTPT

optimizes the selection, or addition,

of generation and
transmission

resources

to meet seasonal energy and peak needs
.
The models are used in two
different ways to answer two different questions.
A
summary comparison of the differences
between the models
and
their
limitations

is provided in
Table
1
.

Table
1
: 10
-
Year and 20
-
Year Model Limitations and Differences

Attribute

10
-
Year Studies

20
-
Year Studies

Tool

Production Cost Model

Capital Expansion Model

Objective
Minimization

Production Cost

Levelized cost (which include
s

capital cost
component)

Focus

Implications of c
apacity
additions and specific
projects
;

planned and in
progress

Understanding potential “energy futures”
and decisions needed to achieve those
futures

Model decides to

Dispatch Generation
hourly,
utilize transmission

Build Generation and Transmission

2013 Interconnection
-
wide Transmission Plan Summary

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26

of
107

Attribute

10
-
Year Studies

20
-
Year Studies

Load

From
BAs

w/ stakeholder
adjustment

From BAs w/ stakeholder adjustment

Resources

Stakeholder specific

LTPT
-
derived additions iterated with
transmission additions

Transmission

Stakeholder specific

LTPT
-
derived additions iterated with
resource additions

Interdependence

Starting point o
f 20
-
Year

Projects 20
-
year futures that may be
compared to, and/or used to construct 10
-
year scenarios that provide more detailed
analysis


I
n addition to the
previously mentioned
major
models that

produce the results discussed in the
Plan, there are a
number
of
additional models that describe
the loads, generation, environment
and policy

attributes
. These include:



Wind and
s
olar models


Create hourly shapes and assist with generation selection

based on
resource availability data and stakeholder input.



Steady
-
s
tate and
d
ynamic models


Reliability modeling tools that describe the detailed
instantaneous or near
-
instantaneous

energy flows.




Hydro models


Determine the behavior of various hydro generators
based on

water
availability, environmental constrai
nts, and operational factors.

The Tools and Models used to develop the 2013 Plan are described in an independent report.
9

Data and Assumptions

The
data and
assumptions used to create the Plan span numerous sources and categories such
as loads, existing and

incremental generation facilities, generation characteristics, and existing
and incremental transmission facilities. Aside from these data and assumptions required to
model the
physical

aspects of the Western Interconnection, WECC staff and stakeholders a
lso
develop
ed

assumptions and gather
ed

equally important
information
on policies, costs, reliability
and environmental considerations.

As with any analysis, assumptions drive the results. TEPPC spends a significant amount of time
and effort in creating and reviewing
data and
assumptions used in the analyses.
The in
-
depth
Data and Assumptions report should be referenced when detailed descr
iptions
or specific

data
are desired.
The Data and Assumption
s

report

is
organized first by data type (
generation,
transmission, loads, etc.)

then study year (2022 or 2032).

Loads and Demand
-