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HomeState Report CardPolicy ScenariosElectricity AdequacyAbout

Electricity Adequacy

Balancing Authority:

California ISO Electricity Adequacy

Dispatchable Capacity
32,706 MW
As of 2021

Expected Hydro
5,140 MW
In September

Expected Solar
5,654 MW
September At 6 PM

Expected Wind
580 MW
In September

Expected Imports
9,357 MW
September At 6 PM

California ISO Generation

Hourly Average for Last 12 Months

California ISO Plants Scaled by Capacity — 2021

More info: Click on Plant Circles

Supply Scenario

California ISO is a grid control area where electricity supply must match demand at all times. Generating plants within the area supply electricity to local consumers. Any surplus of electricity is exported to other areas; any deficit must be made up by imports.

For dispatchable plants using coal, natural gas, nuclear, or other fuels, the plant may be down for maintenance or refueling. Therefore, we must adjust or ‘derate’ Nameplate Capacity to reach what can be actually used, ‘Expected Capacity'. Out of the 41,408 MW of dispatchable capacity in California ISO, only 32,701 MW is expected to be available.

For hydro power, we use the peak generation for each month. This adjusts our estimates for the seasonality of water levels in California ISO.

For solar power, we take the average generation for each month and each hour. This accounts for the daily flucuation of solar, and the seasonal change in daylight hours.

For wind power, we take the average generation less 1 standard deviation for each month. Given the variability of wind, our conservative estimate accounts for ~85% of scenarios.

ResourceCapacity (MW)Change Capacity (+/-)Capacity FactorDerate FactorExpected Capacity (MW)
Dispatchable Capacity (2021)41,408   32,701
  Natural Gas 32,872 27% % 26,298
  Nuclear 2,323 81% % 2,160
  Energy Storage 2,286   % 1,852
  Geothermal 2,104 44% % 926
  Biomass807 44% % 646
  Petroleum 389 2% % 315
  Waste 340 63% % 272
  Other Fossil Fuels 124 74% % 100
  Other 100 45% % 81
  Coal 63 53% % 52
Renewable Capacity (September)30,760   11,438
  Peak Hydro/Pumped Storage8,825   % 5,119
  Average Solar at 6PM15,871   % 5,714
  Average Wind Less 1 Standard Deviation6,064   % 606
Peak Imports (September at 6PM)    9,357
Total72,168   53,496

Demand Scenario

To estimate the demand scenario, we use hourly data from the EIA over the selected date range to find peak demand times. Then users are able to increase/decrease demand to best plan for the region's future.

Electric car adoption is estimated using the average daily commute of California ISO residents, paired with the selected car's efficiency rating. This daily demand is then distributed across the day based on observed charging demand.

Demand response is estimated using the reported "Potential Peak Demand Savings (MW)" for each utility in California ISO. This is applied to the demand curve with the assumption that this potential peak could be implemented at any time.

Demand Type Technology Adoption Adopted Units Demand (MW)
At 6 PM
Baseline Peak Demand 51,104
New Electric Vehicles
To estimate the increased demand of EVs we've done the following:
  • Calculated the kWh/Mile for each car using their published MPGe.
  • Using state private and commercial automobile registration data and average commute distances, we estimate the average daily distance traveled per vehicle, and an estimate of non-electric vehicles within the Balancing Authority.
  • Using a Stanford Study (cited below) on average electric charging demand per-minute, we break down our daily demand estimate by hour, and use the peak hour in the Balancing Authority.
  • The peak demand hour is then scaled by the adoption rate the user chooses.
% 0 0
Residential Demand Response
To estimate the potential reduction in peak demand, we've done the following:
  • Aggregated utility data on residential customer counts for each Balancing Authority
  • Aggregated utility data on peak demand response per residential customer
  • Combined the two datapoints and scaled by the user-entered adoption rate.
% 0 0
Demand Increase/Decrease % 0
Projected Peak Demand       51,104
Operating Reserves   %   3,066
Planning Reserves   %   0
Projected Demand + Reserves       54,170

Surplus/Deficit Scenario Results


Peak Month and Time of Day
Peak Month and Time of Day is found by adding the Demand Assessment estimates to hourly data from the past year.
September at 6PM
Expected Supply
Expected Supply is found by estimating available resources at the peak date and time listed above.
53,432 MW
Peak Demand
Peak Demand is found by adding the Demand Assessment estimates to demand at the peak date and time listed above.
51,104 MW
Peak Demand + Reserves: 54,170 MW
Defecit: -738 MW
Deficit Hours: 14

Estimated Deficit Hours

Per Month

Data compiled using information from EIA Form 860, Form 861, Form 923, the EIA API, EPA Pollution Data, and the Census Bureau
Electric charging estimates are derived from Resilient Societies analysis, and this Stanford study on EV charging.
Air source heat pump estimates are derived from Resilient Societies analysis and real-world data collection.

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