SPSC Study
Technology Breakthroughs
September 19, 2013
Introduction
The main purpose of the 20-year State-Provincial Steering Committee (SPSC) Technology
Breakthrough Studies (“Technology Breakthrough Studies”) is to evaluate how drastic, yet
feasible, reductions in resource costs may change the transmission needs in the 2022-2032
timeframe. The SPSC selected three technologies on which to run breakthrough studies:



Solar Photovoltaic (PV) (utility scale)
Solar Thermal with Six-Hour Storage
Enhanced Geothermal Systems (EGS)
The SPSC provided WECC with revised cost parameters for these technologies and each
breakthrough was studied individually. For example, the solar PV Breakthrough Study changed
only one study assumption – the cost of utility-scale solar PV. In each case, technology capital
costs were changed relative to the 2032 Reference Case.
The premise behind the Technology Breakthrough Studies contrasts well with the Scenario
Planning Steering Group (SPSG) 20-year scenario-based studies. The SPSG studies changed
numerous variables (e.g., technology costs, load levels, generation tax credits, carbon costs)
relative to the 2032 Reference Case. Alternatively, the Technology Breakthrough Studies
changed only a single variable (resource cost). While none of these futures may come to pass,
the Technology Breakthrough Studies are useful as changes from the 2032 Reference Case
results can be attributed to the variable that was changed. This direct causation is useful as any
changes in the transmission expansions from the 2032 Reference Case to the Technology
Breakthrough Studies can be attributed to the input variables that were changed.
Key Questions
The Technology Breakthrough Studies hope to answer key stakeholder questions, including the
following:


How does technology cost breakthroughs impact transmission expansion in the 20222032 timeframe as compared to the 2032 Reference Case?
What is the generation build-out associated with this transmission, and how does it differ
from the 2032 Reference Case under these cost-breakthrough futures?
Study Limitations
In the next planning cycle, WECC can build upon its early success with WECC’s Long-term
Planning Tool (LTPT) and the 20-year study methodology by making improvements to the
model to enhance the tool’s ability to address stakeholder study requests. A number of
Page 1 of 52
2032 Technology Breakthrough Studies
limitations and areas for enhancement have been identified and are described in the 2032
Reference Case report. A more extensive list of model limitations is provided in the “Tools and
Models” section, where the LTPT model is explained in detail.
Input Assumptions
All 2032 study cases are constructed from the 2032 Reference Case as a starting point. As
such, a number of the assumptions used to construct the 2032 Reference Case are carried
through to each subsequent study. This is especially true with regard to detailed modeling
assumptions – these rarely change from study-to-study. Generally, only assumptions about load
levels, generator and transmission technology costs, and fuel pricing change for a particular 20year study. Table 1 includes a description of those assumptions specific to the Technology
Breakthrough Studies, however, that may be in addition to or an alternative of those
assumptions used in the Reference Case. All assumptions not listed in this section are
consistent with those assumptions in the 2032 Reference Case.
The capital and operating and maintenance (O&M) cost provided by the SPSC for the EGS
breakthrough study did not result in any additional geothermal resources being selected. Thus,
the cost breakthroughs, as provided, were not sufficient to cause geothermal deployment based
on a levelized cost of energy (LCOE) as calculated within the LTPT in accordance with TEPPC
approved generating unit costs. Staff re-evaluated the study and determined that the LTPT
began to select additional geothermal resources when the U.S. average geothermal capital cost
was reduced by 50 percent ($2,750/kW in 2012 dollars). To encourage a breakthrough in
geothermal resources, the original EGS breakthrough study was re-run with an even larger (60
percent) reduction in the U.S. average geothermal capital cost, which is reflected in Table 1.
Table 1: Technology Breakthrough Studies Assumptions
Input Parameters
U.S. Average Capital Cost
Solar PV - Tracking (>20 MW)
Solar Thermal - Six Hour
Storage
Geothermal
Units
2032 Reference
Case
SPSC Breakthrough
Cases
2012$/kW
$3,300.00
$1366.84 (-58.6%)
2012$/kW
$7,100.00
$5000.00 (-29.6%)
2012$/kW
$5,500.00
$2200.00 (-60.0%)1
31%
31%
25%
25%
0%
0%
Capital Cost Reductions Applied to U.S. Average
% below 2012
Solar PV - Tracking (>20 MW)
cost
Solar Thermal - Six Hour
% below 2012
Storage
cost
% below 2012
Geothermal
cost
Fixed O&M Costs
1
The EGS Breakthrough Study originally specified $3,991/kW in 2012 dollars (27.4 percent below the
2032 Reference Case value) for the U.S. Average Geothermal Capital Cost.
Page 2 of 52
2032 Technology Breakthrough Studies
Input Parameters
Solar PV - Tracking (>20 MW)
Solar Thermal - Six Hour
Storage
Geothermal
Annual Capacity Factor
Geothermal
2012$/KW-year
2032 Reference
Case
$50.00
SPSC Breakthrough
Cases
$6.81
2012$/KW-year
$65.00
$41.92
2012$/KW-year
$180.00
$216.00
%
Various
(Generator-Specific)
90%
Units
Study Results
The following study results are organized by type. Generation results are presented first,
followed by the transmission expansion results. It is important for the reader to recall that the
LTPT considers transmission costs associated with each generation resource; therefore, the
cost of transmission (grid cost) impacts the selection of generation by the model.
Environmental analysis of the incremental transmission is in progress and will be included with
the report when available.
Generation Results
Generator results are key components for the Technology Breakthrough Studies. “Additions” in
the generation results represent those resources that were added in the 2022-2032 timeframe.
“Existing” generation is any generation assumed in the 2022 Common Case.
Generation Selection
The LTPT adds enough generation in the model iterations to meet four basic goals, in the order
shown:
1. Local policy goals – for most study cases, including the 2032 Reference Case, this is
generally distributed generation (DG) set asides specified in state RPS policies;
2. Generic policy goals – generally state Renewable Portfolio Standard (RPS)
requirements;
3. System energy goals – annual energy required by the system. The model will add
resources in addition to those already selected for policy goals until this goal is met; and
4. System peak goal – to ensure the system has enough resources to meet the system
peak being analyzed.
The LTPT selects resources for the model based on the levelized cost of energy (LCOE) for
each of these goals system wide (i.e., resource deliverability is not considered in resource
selections).
Total Capacity and Additions – Solar PV Breakthrough Study
The Solar PV Breakthrough Study resulted in an Interconnection-wide resource capacity of
366,321 MW in 2032, a net increase of 97,000 MW over the capacity included in the 2022
Page 3 of 52
2032 Technology Breakthrough Studies
Common Case. This is 40,000 MW more than the final capacity of the 2032 Reference Case.
The capacity additions included 89,000 MW of new resources and over 10,000 MW of coal
resources that were present in the 2022 Common Case but were not selected in the Solar PV
Breakthrough Case and so were effectively retired. The resource capacity of the Solar PV
Breakthrough Study is broken down by resource type in Figure 1. Note that due to the
breakthrough in solar PV cost, this resource type represents 28 percent of the Western
Interconnection’s total capacity in 2032. This represents a significant shift from the 2032
Reference Case where solar PV made up only 4 percent of the Western Interconnection’s
capacity. Breakthrough in technology costs for solar PV results in wide-spread implementation
of the technology under this future. Note that this figure introduces the fuel type “gap” which is
gas resource used to serve load in Alberta.
While seven types of solar PV are modeled within the LTPT, including distributed solar PV and
rooftop solar PV, the scope of this solar PV breakthrough study is limited to that of large scale
commercial solar PV projects modeled at Western Renewable Energy Zones . Since the scope
does not include any criteria or assumptions associated with solar PV beyond that of large scale
commercial solar PV, no assertions regarding other solar technologies are made nor can they
be supported beyond the context of this study.
Figure 1: Solar PV Breakthrough Study Total 2032 Generation Capacity
Figure 2 shows the Interconnection-wide net change in resource capacity for the Solar PV
Breakthrough Study in the 2022-2032 timeframe. Approximately 10,000 MW of existing (2022
Common Case) coal resources were displaced by new resource additions. Of the total
Interconnection wide generation capacity, 29 percent consists of new resource additions and 71
percent consists of 2022 Common Case resources.
Page 4 of 52
2032 Technology Breakthrough Studies
Figure 2: Solar PV Breakthrough Study 2022-2032 Net Change in Resource Capacity (MW)
Page 5 of 52
2032 Technology Breakthrough Studies
The resource capacity of the Western Interconnection is further broken down by state in Figure
3. Figure 4 shows the same information geospatially. The majority of solar PV resources are
located in California, Arizona, Nevada and New Mexico.
Figure 3: Solar PV Breakthrough Study Total 2032 Generation Capacity (by State)
Page 6 of 52
2032 Technology Breakthrough Studies
Figure 4: Solar PV Breakthrough Study Total 2032 Generation Capacity
Page 7 of 52
2032 Technology Breakthrough Studies
Notably, there were few coal and combined heat and power (CHP) resources in this future. This
is largely due to solar PV’s significant cost advantage assumed in the study, which caused a
combined 20,000 MW of the 2022 Common Case coal and CHP generation not to be selected
by the model, even though their capital cost was zero, effectively retiring the units. This change
in resource capacity is shown in Figure 5.
Figure 5: Solar PV Breakthrough Study WECC-wide 2022-2032 Change in Resource Capacity
Page 8 of 52
2032 Technology Breakthrough Studies
Figure 6 shows the resources added, by fuel type, in the 2022-2032 timeframe from the Solar
PV Breakthrough Study. The additions totaled 108,007 MW. Nearly 90,000 MW of these
additions were solar PV resources. Wwind resources still were selected, but only those with
extremely high capacity factors – thus rendering them economic even in comparison to solar PV
which experienced a drastic price decrease relative to the 2032 Reference Case. Figure 7
shows where the resources were added in the study timeframe. Figure 8 shows the same
information geospatially. Solar PV resources were added consistently across four key states:
California, Arizona, Nevada and New Mexico.
Figure 6: Solar PV Breakthrough Study 2022-2032 Added Generation Capacity
Page 9 of 52
2032 Technology Breakthrough Studies
Figure 7: Solar PV Breakthrough Study 2022-2032 Added Generation Capacity (by State)
Page 10 of 52
2032 Technology Breakthrough Studies
Figure 8: Solar PV Breakthrough Study 2022-2032 Added Generation Capacity
Page 11 of 52
2032 Technology Breakthrough Studies
Total Capacity and Additions – Solar Thermal Breakthrough Study
The Solar Thermal Breakthrough Study (with six-hour storage) resulted in Interconnection-wide
capacity of 322,946 MW in 2032. This is roughly comparable to the final resource capacity of
the 2032 Reference Case. The resources are broken down by type in Figure 9. Note that solar
thermal with storage represents nearly all of the solar in the diagram. This future represents a
very balanced resource portfolio where wind, water, solar, gas and coal all play critical roles.
The cost reduction of solar thermal was significant enough that the resource became one of the
most economic resources in the Western Interconnection under this future.
Figure 9: Solar Thermal Breakthrough Study Total 2032 Generation Capacity
Page 12 of 52
2032 Technology Breakthrough Studies
Figure 10 shows the Interconnection-wide net change in resource capacity for the Solar
Thermal Breakthrough Study in the 2022-2032 timeframe. No existing (2022 Common Case)
resources were displaced by new resource additions. Of the total Interconnection-wide
generation capacity, 17 percent consists of new resource additions and 83 percent consists of
2022 Common Case resources.
Figure 10: Solar Thermal Breakthrough Study 2022-2032 Net Change in Resource Capacity (MW)
Page 13 of 52
2032 Technology Breakthrough Studies
The generation capacity by state and resource for the Solar Thermal Breakthrough Study is
shown in Figure 11. Figure 12 shows the same information geospatially. Under this
breakthrough technology, Arizona has the largest capacity of solar resources.
Figure 11: Solar Thermal Breakthrough Study Total 2032 Generation Capacity (by State)
Page 14 of 52
2032 Technology Breakthrough Studies
Figure 12: Solar Thermal Breakthrough Study Total 2032 Generation Capacity
The previous discussion focused on the total generation capacity of the Western
Interconnection in 2032. However, the incremental transmission added from 2022-2032 is
driven by the generation additions during that same time period. New generation drives new
transmission in the model. As such, there is value in investigating the type and location of
incremental resources as doing so helps to justify and explain the transmission expansions.
Page 15 of 52
2032 Technology Breakthrough Studies
Figure 13 shows the generation added in the 2022-2032 timeframe from the Solar Thermal
Breakthrough Study. The result is very similar to the Solar PV Breakthrough Study, except fewer
resources were added overall – only 54,216 MW. Over 41,000 MW of these additions were
solar thermal resources. The additions are broken down by state/province in Figure 14. Figure
15 shows the same information geospatially. In this case, the majority of solar thermal
resources were added in Arizona and New Mexico, and to a lesser extent Nevada, Texas and
Utah.
Figure 13: Solar Thermal Breakthrough Study 2022-2032 Added Generation Capacity
Page 16 of 52
2032 Technology Breakthrough Studies
Figure 14: Solar Thermal Breakthrough Study 2022-2032 Added Generation Capacity (by State)
Page 17 of 52
2032 Technology Breakthrough Studies
Figure 15: Solar Thermal Breakthrough Study 2022-2032 Added Generation Capacity
Page 18 of 52
2032 Technology Breakthrough Studies
Total Capacity and Additions – Enhanced Geothermal Systems (EGS) Breakthrough
Study
The EGS Breakthrough Study resulted in Interconnection-wide capacity of 324,730 MW in 2032.
This is roughly comparable to the final resource capacity of the 2032 Reference Case (325,800
MW). The resources are broken down by type in Figure 16. This future represents a very
balanced resource portfolio where wind, water, solar, gas and coal all play critical roles.
Geothermal resources make up a small portion of the resource mix despite its substantial cost
reductions in this future.
Figure 16: Enhanced Geothermal Systems Breakthrough Study Total 2032 Generation Capacity
Page 19 of 52
2032 Technology Breakthrough Studies
Figure 17 shows the Interconnection-wide net change in resource capacity for the Enhanced
Geothermal Systems Breakthrough Study in the 2022-2032 timeframe. No existing (2022
Common Case) resources were displaced by new resource additions. Of the total
Interconnection wide generation capacity, 17 percent consists of new resource additions and 83
percent consists of existing 2022 Common Case resources.
Figure 17: Enhanced Geothermal Systems Breakthrough Study 2022-2032 Net Change in Resource Capacity
(MW)
Page 20 of 52
2032 Technology Breakthrough Studies
The generation capacity by state and resource for the EGS Breakthrough Study is shown in
Figure 18. Figure 19 shows the same information geospatially. Under this breakthrough future,
California has the largest capacity of geothermal resources; however, these resources were
assumed to already exist in 2022.
Figure 18: Enhanced Geothermal Systems Breakthrough Study Total 2032 Generation Capacity (by State)
Page 21 of 52
2032 Technology Breakthrough Studies
Figure 19: Enhanced Geothermal Systems Breakthrough Study Total 2032 Generation Capacity
The previous discussion focused on the total generation capacity of the Western
Interconnection in 2032. However, the incremental transmission added from 2022-2032 is
driven by the generation additions during that same time period. New generation drives new
transmission in the model. As such, there is value in investigating the type and location of
incremental resources as doing so helps to justify and explain the transmission expansions.
Page 22 of 52
2032 Technology Breakthrough Studies
Figure 20 shows the generation added in the 2022-2032 timeframe from the EGS Breakthrough
Study. Over 1,700 MW of these additions were enhanced geothermal resources. The additions
are broken down by state/province in Figure 21. Figure 22 shows the same information
geospatially. In this case, the majority of enhanced geothermal resources were added in
Oregon, with smaller amounts in Utah, Idaho and British Columbia.
Figure 20: Enhanced Geothermal Systems Breakthrough Study 2022-2032 Added Generation Capacity
Page 23 of 52
2032 Technology Breakthrough Studies
Figure 21: Enhanced Geothermal Systems Breakthrough Study 2022-2032 Added Generation Capacity (by
State)
Page 24 of 52
2032 Technology Breakthrough Studies
Figure 22: Enhanced Geothermal Systems Breakthrough Study 2022-2032 Added Generation Capacity
Levelized Cost of Energy
The LTPT selects resources based on the LCOE. The use of LCOE in the LTPT is described in
more detail in the 2032 Reference Case report. Comparing the levelized cost of resources
added during the 2022-2032 timeframe in the Technology Breakthrough Studies allows for the
identification of the most economic resources, as well as information about how resources costs
compare, on average. Figure 23 shows a supply curve for the Solar PV Breakthrough Study that
presents the resources added from 2022-2032, ranked and sorted by resource type and
average LCOE. This supply curve format allows the user to see how much capacity (MW) of a
resource was selected, and at what average cost (LCOE) is representative of these resources.
Note that the LCOE presented on the chart is a weighted average LCOE and careful
interpretation is required. For example, the ~12 GW of wind installed at a cost of $70/MWh
should not suggest that there is ~12 GW of wind available at that energy cost in this scenario.
Most of the wind is available at a greater or lower cost than $70/MWh. Only the weighted
Page 25 of 52
2032 Technology Breakthrough Studies
average cost is presented. This weighted average simplifies the diagram and makes for easy
resource comparison.
Figure 23 presents the LCOE supply curve for those resources selected by the model during the
2022-2032 timeframe under the Solar PV Breakthrough Study. The least expensive resource
was solar PV. This low average cost reflects the technology cost assumptions assumed in this
study. This low cost caused many solar PV resources to be selected by the model. Hydro was
the second most economic resource and entered the “addition stack” after the “best” (e.g., high
capacity factor) solar PV resources were fully utilized. The remaining resources were wind, gap
resources and varying types of DG that were “forced” into the study to emulate policy
requirements.
Figure 23: Solar PV Breakthrough Study LCOE of Resource Additions (2012 dollars)
Page 26 of 52
2032 Technology Breakthrough Studies
The average LCOE of the resource additions in the Solar Thermal Breakthrough Study are
presented in Figure 24. Note that in this case the breakthrough technology, solar thermal, was
less economic, on average, than the hydro and high-quality wind resources. It is also worth
noting that the solar PV cost reduction in the previous case pushed the average LCOE of the
resource to $40/MWh while the cost breakthrough for solar thermal was near $70/MWh.
Figure 24: Solar Thermal Breakthrough LCOE of Resource Additions (2012 dollars)
Page 27 of 52
2032 Technology Breakthrough Studies
The average LCOE of the resource additions in the Enhanced Geothermal Systems
Breakthrough Study are presented in Figure 25. As with the 2032 Reference Case, wind
resources were the most economical additions. The study’s assumed significant cost reductions
for geothermal allowed a small amount of geothermal to be more economical than new gas-fired
resources.
Figure 25: Enhanced Geothermal Systems Breakthrough LCOE of Resource Additions (2012 dollars)
Resource Adequacy and Operational Flexibility
Resource adequacy and operational flexibility are important elements of reliable grid operation.
Resource adequacy is not a major concern in the LTPT results because the optimized
generation selection includes designated reliability and balancing units and ensures that the
System Peak Demand Goal is met – for the Solar PV, Solar Thermal and EGS Breakthrough
Studies, the system peak reserves were 35,900 MW (18 percent of the system peak demand),
42,900 MW (22 percent of the system peak demand), and 36,600 MW (19 percent of the system
peak demand), respectively. Operational flexibility considerations, on the other hand, are not
part of the LTPT optimization and need to be evaluated.
Comparing levels of flexibility from study case results with levels from a system known to be
reliable (i.e., today’s grid) enables the identification of potential future operational challenges
and areas for additional evaluation. To make this comparison, TEPPC developed the Flexible
Resource Indicator, the calculation for which is shown below. A detailed description of the
Page 28 of 52
2032 Technology Breakthrough Studies
Flexible Resource Indicator and its use in the 20-year analysis can be found in the 2032
Reference Case report.
Flexible Resource Indicator =
Flexible Generation2 Capacity
Variable Generation Capacity
The indicator is provided as an aggregated Interconnection-wide value. For example, a Flexible
Resource Indicator equal to 5 means that Interconnection-wide there are 5 MW of flexible
generation for every 1 MW of VG.
The Flexible Resource Indicator values are presented in Figure 26. The calculation was
performed for 2012 and 2022 using the 2022 Common Case data to provide context. The
information shows that in the 2022 Common Case there are approximately 2 MW of flexible
resources for every 1 MW of VG. This is a large departure from the ~5 MW of flexible generation
for every 1 MW of VG present on the system in 2012.
All three Technology Breakthrough Studies have Flexible Resource Indicator values lower than
the 2032 Reference Case. The indicator values decrease from 2012 to the 2022 Common
Case, which suggests that states are adding large amounts of renewable resources and fewer
gas burning resources to achieve RPS compliance. The decreasing indicator values also
suggest that operating the transmission system under these futures with higher levels of VG will
take precision, cooperation, robust transmission and a heavy reliance on existing and potentially
new balancing resources. In all three Technology Breakthrough Studies, large amounts of VG,
solar in the case of Solar PV and Solar Thermal Breakthroughs, and wind in the case of
Enhanced Geothermal Breakthrough, were added in the 2022-2032 timeframe. During that
same timeframe, little or no gas resources were added in the Technology Breakthrough Studies.
These low Flexible Resource Indicator values suggest that there may be difficulties in balancing
these large capacities of variable generation.
2
Flexible Generation Capacity consists of the total gas-fired generation capacity and 15 percent of the
total hydro generation capacity.
Page 29 of 52
2032 Technology Breakthrough Studies
Figure 26: Flexible Resource Indicator
The complementary nature of wind and solar is not considered in the Flexible Resource
Indicator. The indicator is designed to point out operational complexities that may arise with
large penetrations of VG. The indicator is also useful in identifying futures that look similar to the
grid today, or those futures that may look and operate substantially differently. A more detailed
and thorough analysis is required to evaluate the plausibility of operating these types of high-VG
systems. The indicator’s value is by no means conclusive or prohibitive of these futures.
Transmission Results
When reviewing the transmission results, recall that these are modeling results based on the
input parameters. The results can inform choices about transmission expansion, but many
factors contribute to ultimate decisions about building or not building any specific transmission
expansion. As mentioned previously, all of the transmission results are AC expansions. The
LTPT has the capability to evaluate and choose DC expansions; however, these were not fully
explored due to time restrictions.
The LTPT consistently showed expansions near the California Bay Area and between the
Washington load areas. These are due to the high concentration and close proximity of load
areas in these portions of the Western Interconnection. The focus of the LTPT studies is on
transmission connections between load areas in the Western Interconnection, thus assumptions
were made about transmission reinforcements within TEPPC load areas and between close
proximity load areas - refer to the Tools and Models report for more detail on the LTPT modeling
and limitations. The flows between load areas can depend on the reinforcement internal to load
areas, especially when load areas are in close proximity and they are all reinforced internally.
Such is the case with the California Bay Area and between the Washington load areas. These
portions of the Western Interconnection are very sensitive to transmission and generation
dispatch changes, whether they are regional or internal to load areas. In future LTPT models, it
Page 30 of 52
2032 Technology Breakthrough Studies
may be better to aggregate load areas that are in close proximity so that the focus remains on
Interconnection-wide planning.
Figure 27, Figure 28 and Figure 29 show the transmission expansions for the Solar PV, Solar
Thermal, and Enhanced Geothermal Breakthrough Studies, respectively. These expansions
include all those added in all system condition expansion analyses. The best solar PV and solar
thermal development areas are in the southwestern portion of the Western Interconnection. The
expansions in both of the Solar Breakthrough Studies are extremely large and very similar. This
is not unexpected because a great amount of conventional thermal generation is being
displaced by more cost competitive solar resources under the breakthrough criteria. Another
observation that became apparent from the Solar Breakthrough Studies was that the
transmission expansions for seasonal conditions other than summer were more extensive than
that of the summer condition. These observed expansion results associated with the Solar
Breakthrough Studies are attributable to a number of factors including:

Summer peak demand is higher in the southern portion of the Western Interconnection,
where solar availability is predominant, requiring less transmission expansion.

Winter peak demand is higher in the northern portion of the Western Interconnection,
where solar availability is remote, requiring more transmission expansion.

During the shoulder seasons (spring and fall), load demand in the Western
Interconnection as a whole is less than in the summer. There is a greater percentage of
solar in the overall mix of generation serving load in the Western Interconnection during
these conditions, resulting in more extensive transmission expansion in the Desert
Southwest portion of the Western Interconnection.
The expansions in both Solar Breakthrough Studies were very similar, emanating from the
southwestern portion of the Western Interconnection. Although solar expansions were closer to
load centers than in most of the other study cases, solar resources still required significant
transmission expansions to bring the relatively remote resources to load.
There was little displacement of thermal generation resulting from the Enhanced Geothermal
Breakthrough Study. As a result, the transmission expansions associated with the enhanced
geothermal breakthrough were similar to that of the 2032 Reference Case and were in the
eastern and northwestern portions of the Western Interconnection, reflecting the large amount
of wind resources that were added in this study.
Page 31 of 52
2032 Technology Breakthrough Studies
Figure 27: All Solar PV Breakthrough Expansions
Page 32 of 52
2032 Technology Breakthrough Studies
Figure 28: All Solar Thermal Breakthrough Expansions
Page 33 of 52
2032 Technology Breakthrough Studies
Figure 29: All Enhanced Geothermal Breakthrough Expansions
Page 34 of 52
2032 Technology Breakthrough Studies
These expansions were added by the tool in the 2022-2032 timeframe but they do not represent
all high-voltage incremental projects assumed in the tool for the 2012-2032 timeframe. The
Common Case Transmission Assumptions (CCTA) included in the 2022 Common Case
represents the set of high-probability transmission projects that are assumed in the analysis,
and were also “added” in the 2012-2022 timeframe. Thus, the total transmission additions would
be those added by the LTPT from 2022-2032 and the set of CCTA projects that were included in
the model. Figure 30, Figure 31 and Figure 32 show the transmission expansions for the Solar
PV, Solar Thermal, and Enhanced Geothermal Breakthrough Studies, respectively, with the
CCTA.
Figure 30: All Solar PV Breakthrough Study Expansions and CCTA
Page 35 of 52
2032 Technology Breakthrough Studies
Figure 31: All Solar Thermal Breakthrough Study Expansions and CCTA
Page 36 of 52
2032 Technology Breakthrough Studies
Figure 32: All Enhanced Geothermal Breakthrough Study Expansions and CCTA
The heavy summer condition LTPT expansion, CCTA, generation dispatch, and load distribution
for the Solar PV, Solar Thermal, and Enhanced Geothermal Breakthrough Studies are shown in
Figure 33, Figure 34 and Figure 35, respectively. The major expansions in both of the Solar
Breakthrough Studies move generation surpluses in the Western Interconnection to those areas
that are generation deficient. The transmission expansion for the Solar PV Breakthrough Study
is focused in the AZ-CA corridor, whereas the transmission expansion for the Solar Thermal
Breakthrough Study has many lightly loaded expansions from the Desert Southwest to Basin
portions of the Western Interconnection. The major expansions in the Enhanced Geothermal
Breakthrough Study are from generation surpluses in the western portions of the Western
Interconnection, primarily wind resources, to the central portions of the Western Interconnection
that are generation deficient. In the Enhanced Geothermal Breakthrough Study, the LCOE of
geothermal generation is made marginal with the tight LCOE spreads between wind and gas
resource additions. As a result, geothermal is included in the generation mix, mostly in the
western portion of the Western Interconnection. This introduces a west-to-east transmission
expansion need.
Page 37 of 52
2032 Technology Breakthrough Studies
Figure 33: Solar PV Breakthrough Study Heavy Summer LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 38 of 52
2032 Technology Breakthrough Studies
Figure 34: Solar Thermal Breakthrough Study Heavy Summer LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 39 of 52
2032 Technology Breakthrough Studies
Figure 35: Enhanced Geothermal Breakthrough Study Heavy Summer LTPT Expansions, CCTA, and State
Generation Dispatch and Load
The light spring condition LTPT expansion, CCTA, generation dispatch, and load distribution for
the Solar PV, Solar Thermal, and Enhanced Geothermal Breakthrough Studies are shown in
Figure 36, Figure 37 and Figure 38, respectively. The light spring condition has low loads and
high renewable energy output, so a large amount of remote resources are contributing. In both
of the Solar Breakthrough Studies there was an extremely large (~30 GW) and concentrated
generation expansion, which resulted in the need for large expansions from the generation
surpluses in the south to the rest of the Western Interconnection that are primarily generation
deficient.
In the Enhanced Geothermal Breakthrough Study, the LCOE of geothermal resource additions
fits within the LCOE spread between wind and gas resource additions. As a result, these
geothermal resource additions significantly reduced the need for new gas resources - as
compared with the 2032 Reference Case. Gas resources are typically the first to be redispatched to ensure a balance between total load and resources. The Enhanced Geothermal
Page 40 of 52
2032 Technology Breakthrough Studies
Breakthrought Study thus had less flexibility (compared with the Referene Case) in balancing its
load and resources since it didn’t have as many gas resources. The light spring condition had
such a low load and so few gas resources that reducing the generation of all gas resources
wasn’t enough to bring the total generation down to the load level. The generation of most of the
local, flexible generation was reduced to achieve a load-resource balance. As a result, most of
the generation was from remote renewable resources, which caused a large transmission
expansion.
Figure 36: Solar PV Breakthrough Study Light Spring LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 41 of 52
2032 Technology Breakthrough Studies
Figure 37: Solar Thermal Breakthrough Study Light Spring LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 42 of 52
2032 Technology Breakthrough Studies
Figure 38: Enhanced Geothermal Breakthrough Study Light Spring LTPT Expansions, CCTA, and State
Generation Dispatch and Load
The light fall condition LTPT expansion, CCTA, generation dispatch, and load distribution for the
Solar PV, Solar Thermal, and Enhanced Geothermal Studies are shown in Figure 39, Figure 40
and Figure 41, respectively. The light-fall condition has no output from either solar PV or solar
thermal resources, so the Solar Breakthrough Study expansions were primarily driven by wind.
The Solar PV Breakthrough Study had many expansions in the south to deliver the high wind
contributions in New Mexico to the generation deficit in the Desert Southwest. The major
expansions in both of the Solar Breakthrough Studies move generation surpluses in the
Western Interconnection to those areas that are generation deficient. The major expansions in
the Enhanced Geothermal Breakthrough Study are from the generation surpluses in the
southeast and east to the central and west portions of the Western Interconnection that are
generation deficient.
Page 43 of 52
2032 Technology Breakthrough Studies
Figure 39: Solar PV Breakthrough Study Light Fall LTPT Expansions, CCTA, and State Generation Dispatch
and Load
Page 44 of 52
2032 Technology Breakthrough Studies
Figure 40: Solar Thermal Breakthrough Study Light Fall LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 45 of 52
2032 Technology Breakthrough Studies
Figure 41: Enhanced Geothermal Breakthrough Study Light Fall LTPT Expansions, CCTA, and State
Generation Dispatch and Load
The heavy winter condition LTPT expansion, CCTA, generation dispatch and load distribution
for the Solar PV, Solar Thermal, and Enhanced Geothermal Breakthrough Studies are shown in
Figure 42, Figure 43 and Figure 44, respectively. The major expansions in both of the Solar
Breakthrough Studies deliver generation surpluses in the Western Interconnection to those
areas that are generation deficient. The major expansions in the Enhanced Geothermal
Breakthrough Study are from the generation surpluses in the outer portions of the Western
Interconnection to the inner portions that are primarily generation deficient.
Page 46 of 52
2032 Technology Breakthrough Studies
Figure 42 Solar PV Breakthrough Study Heavy Winter LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 47 of 52
2032 Technology Breakthrough Studies
Figure 43 Solar Thermal Breakthrough Study Heavy Winter LTPT Expansions, CCTA, and State Generation
Dispatch and Load
Page 48 of 52
2032 Technology Breakthrough Studies
Figure 44: Enhanced Geothermal Breakthrough Study Heavy Winter LTPT Expansions, CCTA, and State
Generation Dispatch and Load
Page 49 of 52
2032 Technology Breakthrough Studies
Costs and Carbon Emission
Figure 45 shows the capital cost and the weighted average LCOE for the 2032 Reference Case,
the High EE/DR/DG3 case (for reference), and the Technology Breakthrough Studies.
Compared to the 2032 Reference Case, the Solar Breakthrough Studies have higher total
capital cost expenditures driven largely by differences in their transmission capital costs.
However, the average LCOE in the Solar Breakthrough Studies was lower than the 2032
Reference Case. This suggests that production cost savings offset the capital cost investments
in solar within the context of the Technology Breakthrough Studies. The costs of the Enhanced
Geothermal Breakthrough Study were similar to those of the 2032 Reference Case.
Another noteworthy observation was gleaned by comparing WECC’s Scenario 2 Study (“Focus
on Clean Energy”) results4 with those of the Solar Breakthrough Studies. While Scenario 2
criteria included similar solar breakthrough assumptions, Scenario 2 also assumed a high
carbon price ($100/ton). The inclusion of a high carbon price assumption in Scenario 2 resulted
in a large amount of existing gas and coal-fired generation being displaced by solar generation.
In the Solar Breakthrough Studies, only coal-fired resources were displaced since a high carbon
price was not assumed. As a result, the average LCOE in the Solar Breakthrough Studies was
much lower than that of Scenario 2 due to the presence of lower-cost coal resources that were
not selected in Scenario 2.
Figure 45: Capital Cost and LCOE Results (2012 dollars)
Both of the Solar Breakthrough Studies feature total CO2 emission levels lower than the 2032
Reference Case. These represent 10-year reductions from the level observed in the 2022
3
4
For the purposes of this report, DR and DSM are synonymous.
The Scenario 2 “Focus on Clean Energy” report includes the in-depth study description, analyses and
results.
Page 50 of 52
2032 Technology Breakthrough Studies
Common Case with reductions primarily due to the fact that solar resources were added in the
2022-2032 timeframe and that these resources do not emit carbon as a byproduct of energy
generation. The CO2 production, as shown in Figure 46, of the Enhanced Geothermal
Breakthrough Study was similar to that of the 2032 Reference Case which would be expected
since the fuel mix of the total capacity in the two cases is quite similar.
Figure 46: CO2 Production
Page 51 of 52
2032 Technology Breakthrough Studies
Study Summary
The following findings summarize the key results from Technology Breakthrough Studies.
Current modeling assumptions were not sufficient to make geothermal,
enhanced or otherwise, resources economically viable
Minimal geothermal resources were selected in the Enhanced Geothermal Breakthrough Study
despite a 60 percent capital cost reduction with very similar to those of the 2032 Reference
Case.
Capital cost reductions assumed in the Solar Breakthrough Studies
resulted in widespread adoption of solar
In both Solar Breakthrough Studies, the assumed solar cost breakthroughs resulted in widespread adoption of solar resources. Given these pricing assumptions, they represent some of
the most economic resources in the Western Interconnection, with everything else being held
equal.
Solar Breakthrough Studies resulted in large transmission expansions
Large-scale implementation of both solar PV and solar thermal result in extensive transmission
expansions, which is expected since a large amount of existing (2022 Common Case)
resources (mainly coal) were displaced by a large amount of solar resources, primarily in the
Desert Southwest portion of the Western Interconnection. The solar resources added in these
study cases were closer to load centers than other renewable resources (e.g., wind); however,
the solar additions were so large (approximately 30 GW) and were concentrated in the Desert
Southwest (i.e., a small portion of the Western Interconnection) that significant transmission
expansions were needed to deliver these resources to the rest of the Western Interconnection.
Notably, the Scenario 2 future also had significant solar additions and large transmission
expansions emanating from the Desert Southwest.
Solar Breakthrough Studies had significant CO2 reductions and a lower
LCOE, but higher capital costs
Adding large amounts of solar PV and solar thermal resources, as in the Solar Breakthrough
Studies, resulted in a decrease in Interconnection-wide CO2 emissions as compared to the 2032
Reference Case due to the displacement of a large amount of existing generation (primarily
coal).
Page 52 of 52