JOUL, Volume
4
Supplemental Information
Role of Long-Duration Energy Storage
in Variable Renewable Electricity Systems
Jacqueline A. Dowling, Katherine Z. Rinaldi, Tyler H. Ruggles, Steven J. Davis, Mengyao
Yuan, Fan Tong, Nathan S. Lewis, and Ken Caldeira
1. Model formulation
1.1. Nomenclature
Symbol
Unit
Description
g
kW
Generation technology (wind, solar)
v
kW
Energy conversion (electrolyzer, fuel cell)
s
kWh
Energy storage (PGP storage, battery storage)
f roms
kW
Discharge from energy storage
tos
kW
Charge to energy storage
t
h
Time step, starting from 1 and ending at
T
c
capital
$/kW for generation
or conversion
$/kWh for storage
(Overnight) capital cost
c
fixed
$/kW/h for generation
or conversion
$/kWh/h for storage
Fixed cost
c
fixed O&M
$/kW/yr
Fixed operating and maintenance (O
&
M) cost
c
var
$/kWh
Variable cost
f
-
Capacity factor (generation technology)
h
h/year
Average number of hours per year
i
-
Discount rate
n
yrs
Project life