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Page S1 of S76
The influence of regional geophysical resource
variability on the value of single- and multi-storage
technology portfolios
Anna X. Li
1+
*
, Edgar Virgüez
2+
*
, Jacqueline A. Dowling
2+
, Alicia Wongel
2
, Dominic Covelli
1
, Tyler H.
Ruggles
2
, Natasha Reich
1
, Nathan S. Lewis
1,3
*
, Ken Caldeira
2,4
*
1
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena,
California, 91125, United States.
2
Department of Global Ecology, Carnegie Institution for Science, Stanford, California, 94305,
United States.
3
Beckman Institute, California Institute of Technology, Pasadena, California, 91125, United States.
4
Gates Ventures LLC, Kirkland, Washington, 98033, United States.
+ A.X.L., E.V., and J.A.D. contributed equally to this paper (equally contributing first authors)
* Corresponding authors:
- Anna Li (li.anna6389@gmail.com)
- Edgar Virgüez (evirguez@carnegiescience.edu)
- Nate Lewis (nslewis@caltech.edu)
- Ken Caldeira (kcaldeira@carnegiescience.edu)
The supplementary material for this study includes:
-
Figures S1-S46 (pages S2 to S35)
-
Tables S1-S11 (pages S36 to S76)
Page S2 of S76
Figure
S1. Electricity sources, sinks, and storage technologies within the macroscale energy
model.
Arrows indicate the direction of electricity flow, and shaded shapes represent nodes in which
electricity can be stored. Conventional Li-ion batteries (Li-ion) were modeled with combined energy
and power components and were fixed to a duration of 4 h.
Storage X
was modeled with separate
power- and energy-storage components. Electrolytic hydrogen storage was modeled with separate
power- and energy-storage components, in which charging and discharging components could have
different capacities.
Page S3 of S76
Figure
S2. Base case costs and efficiencies assumed for the short-, mid-, and long-duration
storage technologies considered in this study.
Base case energy-capacity costs, power-capacity costs, and round-trip efficiencies (designated by the
colored area of pie charts) of different storage technologies modeled herein. In this work,
electrolytic hydrogen was considered as a prototypical long-duration storage technology, Li-ion
batteries provided a prototypical short-duration storage technology, and the other technologies were
labeled as mid-duration storage technologies. Table S4 supports this figure. See the Methods section
for additional base case cost assumption details.
*
Individual Li-ion and metal-air batteries have energy- and power-capacities that cannot be
independently sized. Thus, based on their fixed durations (energy- to power-capacity ratio) of 4 h
and 100 h, respectively, their total costs are best described by the diagonal lines illustrated in Figure
1. For metal-air batteries, the energy- and power-capacity costs shown in this plot were calculated by
splitting the total overnight cost used for modeling through the method described in Table S4.
† Because electrolytic hydrogen energy storage has separate technologies for charging and
discharging, the power-capacity cost was calculated by assuming that 0.25 kW of charging capacity
was installed for every 1 kW of discharging capacity, as was observed in solar- and wind-based least-
cost systems with energy storage provided by both Li-ion batteries and hydrogen energy storage.
CAES also has separate technologies for charging and discharging, and its power-capacity cost was
calculated with the same ratio as that used for hydrogen energy storage.
Page S4 of S76
Figure S3. Base case energy- and power-capacity total overnight costs of energy storage
technologies modeled, where Li-ion total costs are shown as a dashed line.
Although Li-ion costs have been divided by Hunter et al. into an energy-capacity cost of 326 $/kWh
and power-capacity cost of 251 $/kW, individual Li-ion batteries have energy- and power- capacities
that cannot be independently sized. Thus, for the 4-hour Li-ion battery considered here, if the
battery is sized based on energy capacity, then the energy-capacity cost is effectively 326
$/kWh+251 $/kW4 h=388.75 $/kWh, and the power-capacity cost is effectively 0 $/kW. In
contrast, if the battery is sized based on power capacity, then the energy-capacity cost is effectively 0
$/kW and the power-capacity cost is effectively 388.75 $/kWh4h=1555 $/kW. Thus, Li-ion battery
costs are most accurately described by the dashed (purple) line connecting 388.75 $/kWh on the x-
axis and 1555 $/kW on the y-axis.
Similarly, individual metal-air batteries have energy- and power-capacities that cannot be
independently sized. We represent metal-air batteries based on Form Energy’s claimed 100 h iron-air
batteries that have a total cost of 20 $/kWh. Because we know only the total cost of these iron-air
batteries, their energy and power-capacity costs are visualized by splitting this total cost based on the
ratio of energy-capacity cost to power-capacity cost used for metal-air batteries.
For the 100h metal-air battery considered here, if the battery is sized based on energy capacity, then
the energy-capacity cost is effectively 20 $/kWh, and the power-capacity cost is effectively 0 $/kW.
In contrast, if the battery is sized based on power capacity, then the energy-capacity cost is
effectively 0 $/kW and the power-capacity cost is effectively 20 $/kWh100 h=2000 $/kW. Thus,
metal-air battery costs are most accurately described by the dashed (gray) line that connects 20
$/kWh on the x-axis and 2000 $/kW on the y-axis.
Page S5 of S76
Figure S4. CONUS system costs for combinations of short-, mid-, and long-duration storage
using wind and solar costs predicted for the year 2050.
Cost contributions of technologies in wind and solar generation-based systems with one, two, and
three storage technologies. Wind and solar generation costs are the lower bound values for the
“Moderate” scenario in the National Renewable Energy Laboratory (NREL)’s Annual Technology
Baseline (ATB) report for the year 2050. System costs when:
(A) Only one storage technology was available: Li-ion batteries,
RFB
(redox-flow
batteries)
, Gravity
energy storage,
PSH
(Pumped-Storage Hydropower)
, CAES
(Compressed Air Energy Storage)
, Thermal
energy storage
, Metal-Air
battery storage,
or hydrogen energy storage.
(B) Two storage technologies were available: Li-ion batteries, with the second storage
technology being a mid-duration storage technology or hydrogen energy storage.
(C) Two storage technologies were available: Hydrogen energy storage, with the second
storage technology being a mid-duration storage technology.
(D) Three storage technologies were available: Li-ion batteries and hydrogen energy
storage, with the third storage technology being a mid-duration storage technology.
Page S6 of S76
Figure S5. If the cost of Li-ion batteries were much lower than current costs, deployment of
Li-ion batteries would be much more effective for reducing total system costs and would
replace utilization of two mid-duration storage technologies (gravity energy storage and
PSH) as compared to the base case.
Cost contributions of technologies in a wind and solar generation-based CONUS system, with one,
two, and three storage technologies. The total cost of Li-ion batteries was 100 $/kWh, a four-fold
decrease from the base case. Costs of all other technologies were kept at the base case values.
System costs when:
(A) Only one storage technology was available:
Li-ion
batteries,
RFB
(redox-flow
batteries)
, Gravity
energy storage,
PSH
(Pumped-Storage Hydropower)
, CAES
(Compressed Air Energy Storage)
, Thermal
energy storage
, Metal-Air
battery storage,
or
Hydrogen
energy storage.
(B) Two storage technologies were available: Li-ion batteries, with the second storage
technology being a mid-duration storage technology or hydrogen energy storage.
(C) Two storage technologies were available: Hydrogen energy storage, with the second
storage technology being a mid-duration storage technology.
(D) Three storage technologies were available: Li-ion batteries and hydrogen energy
storage, with the third storage technology being a mid-duration storage technology.
Page S7 of S76
Figure
S6. Role of redox-flow battery (RFB) energy storage in CONUS systems with
different combinations of short-, mid-, and long-duration storage.
The role (optimized discharge time) of mid-duration storage technologies (here represented by
redox-flow batteries, RFB) depended on the availability of short- and long-duration storage. Energy
in storage over one year when:
(A) RFB was the only storage technology.
(B) RFB had lower power costs than Li-ion batteries and thus acted as short-duration storage.
(C) RFB had lower energy costs than electrolytic hydrogen and thus acted as long-duration
storage.
(D) RFB was not present in the least-cost system, because less expensive short- and long-duration
storage technologies were available.
Page S8 of S76
Figure
S7. Role of redox-flow battery (RFB) energy storage in CAISO systems with different
combinations of short-, mid-, and long-duration storage.
Figure
S8. Role of redox-flow battery (RFB) energy storage in ERCOT systems with
different combinations of short-, mid-, and long-duration storage.
Page S9 of S76
Figure
S9. Role of redox-flow battery (RFB) energy storage in ISO-NE systems with
different combinations of short-, mid-, and long-duration storage.
Figure
S10. Role of redox-flow battery (RFB) energy storage in MISO systems with different
combinations of short-, mid-, and long-duration storage.
Page S10 of S76
Figure S11. Role of pumped-storage hydropower (PSH) energy storage in CONUS systems
with different combinations of short-, mid-, and long-duration storage.
The role (optimized discharge time) of mid-duration storage technologies (here represented by
pumped-storage hydropower, PSH) depended on the availability of short- and long-duration storage.
Energy in storage over one year when:
(A) PSH was the only storage technology.
(B) PSH competed with short-duration storage (Li-ion batteries).
(C) PSH competed with long-duration storage (electrolytic hydrogen).
(D) PSH was not present in the least-cost system when both short- and long-duration storage
were available.
Page S11 of S76
Figure
S12. Role of pumped-storage hydropower (PSH) energy storage in CAISO systems
with different combinations of short-, mid-, and long-duration storage.
Figure
S13. Role of pumped-storage hydropower (PSH) energy storage in ERCOT systems
with different combinations of short-, mid-, and long-duration storage.
Page S12 of S76
Figure
S14. Role of pumped-storage hydropower (PSH) energy storage in ISO-NE systems
with different combinations of short-, mid-, and long-duration storage.
Figure
S15. Role of pumped-storage hydropower (PSH) energy storage in MISO systems
with different combinations of short-, mid-, and long-duration storage.
Page S13 of S76
Figure S16. Role of gravity energy storage in CONUS systems with different combinations
of short-, mid-, and long-duration storage.
The role (optimized discharge time) of mid-duration storage technologies (here represented by
gravity energy storage) depended on the availability of short- and long-duration storage. Energy in
storage over one year when:
(A) Gravity energy storage was the only storage technology.
(B) Gravity energy storage competed with short-duration storage (Li-ion batteries).
(C) Gravity energy storage competed with long-duration storage (electrolytic hydrogen).
(D) Gravity energy storage was not present in the least-cost system when both short- and long-
duration storage were available.