Scenarios

The WECC forecast spans three scenarios: a Central Scenario, High Demand and Low Renewables.

Overview matrix

Each scenario adjusts a set of levers relative to the Central Scenario. Bold values differ from the Central Scenario.

Every scenario starts from the same existing fleet and the same committed interconnection queue projects. Technology costs, fuel prices and carbon allowance prices are the same in every scenario.

Central Scenario

The Central Scenario represents Modo Energy’s view of the most likely path for the WECC market. Every lever sits at its base setting, and the other two scenarios are described as deviations from this case.

California demand follows the CPUC SERVM 2026 net load forecast, which is anchored on the CEC’s 2025 Integrated Energy Policy Report (IEPR) Planning Scenario. The capacity expansion model meets the CPUC’s 25 MMT by 2035 emissions path for California. CAISO gas plants retire on the schedule in the CPUC’s assumptions for the 2026-27 Transmission Planning Process (TPP). Read more about these assumptions on the Capacity Expansion Model and Demand pages.

High Demand

High Demand models faster load growth in California. California demand follows the CEC 2025 IEPR Local Reliability scenario instead of the Planning Scenario. The CEC uses Local Reliability as its high-demand case for local resource adequacy. It assumes more data centers, more fuel substitution and more EV charging, with less behind-the-meter solar and less energy efficiency.

The scenario adds about 41 TWh of CAISO net load by 2045. Data centers supply about half of it. EV charging and fuel substitution supply most of the rest, and less behind-the-meter solar and energy efficiency supply the remainder. CAISO peak load is about 7 GW higher than the Central Scenario by 2045.

The extra load is the CEC’s hourly difference between the two scenarios, for each load component and each CAISO zone. Each component brings its own hourly shape. Data centers add a near-flat block, EV charging adds most at night, and less behind-the-meter solar adds load around midday. The same hourly difference is added to every weather year, so the extra load does not change with the weather.

CAISO build limits scale with the higher peak load, so the model can build more to serve it. By 2045, High Demand builds more solar and onshore wind than the Central Scenario, and fewer batteries.

Low Renewables

Low Renewables models slower decarbonization in California. Three levers move together: less new solar and wind, a looser emissions cap, and later gas retirements.

• Solar and wind build limits: CAISO solar and onshore wind limits keep total new build in line with the CPUC 2026-27 TPP base portfolio. Any allowance a year does not use carries into later years.
• Emissions cap: The California cap follows the CPUC 30 MMT by 2035 path instead of 25 MMT, and its 2045 target is reached five years late. The cap therefore sits above the Central Scenario’s until 2050.
• Gas retirements: Every CAISO gas retirement in the CPUC 2026-27 TPP schedule happens five years later.

The tighter limits cut the solar the model can build in CAISO by about 40 GW by 2045. The model does not use all of the lower limit. By 2045, Low Renewables builds less solar, onshore wind and battery capacity than the Central Scenario, and more geothermal.

New build per scenario

Each scenario builds a different fleet in CAISO. New build counts committed queue projects and capacity expansion model builds in PG&E, SCE and SDG&E. No scenario builds new gas or offshore wind.

By 2045, High Demand builds the most solar and onshore wind. Low Renewables builds the least solar, onshore wind and battery capacity. The Central Scenario builds the most batteries.

Revenue opportunities per scenario

Each scenario builds a different fleet, and that fleet shapes the prices a battery can capture. The four-hour top-bottom (TB4) spread measures the annual revenue available to a four-hour battery from the daily gap between the highest and lowest prices.

High Demand is the strongest revenue environment for most of the horizon. It adds load and builds fewer batteries than the Central Scenario, and its spreads pull further ahead after 2040.

Low Renewables tracks the Central Scenario closely. Its spreads are mostly a little lower from the mid-2030s to the early 2040s, and the two move together after that.