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Released June 18, 2025 | SUGAR LAND
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Written by Paul Wiseman for Industrial Info Resources (Sugar Land, Texas)--Balancing a grid's fluctuating supply and demand needs is more challenging than ever for grid operators when intermittent renewable supplies are in the mix. The California Independent System Operator (CAISO), which manages most of the state's grid, is dealing with the irony of curtailing more and more wind and solar power even as the supply capacities of those sources increase. That is according to new data from the U.S. Energy Information Administration (EIA).
The EIA reports that "In 2024, CAISO curtailed 3.4 million megawatt-hours (MWh) of utility-scale wind and solar output, a 29% increase from the amount of electricity curtailed in 2023."
Of all energy curtailed in CAISO last year, solar accounted for 93%. Curtailment happened mostly in the spring, when, to quote the old song, there was "plenty of sunshine" yet little demand for heat or air conditioning in the mild days of that season.
This might raise the question as to whether the state has reached a saturation point with these renewables--and, if so, would that curtail the installation of new capacity?
In fact, California's renewable power supply has grown exponentially in the last 10 years. The EIA says in 2014 the state had 9.7 gigawatts (GW) of wind and solar capacity. By 2024 the number had almost tripled, to 28.2 GW.
As noted, wind and solar generation only work when there is wind or sunshine. The latter is pretty predictable and regular, the former less so. And when that supply does not coincide with demand, it creates two problems, the EIA points out:
That's true, but it's considered to always be necessary in the background, for "base load," and it's harder to ramp quickly, say at sundown or when clouds suddenly hide the sun, if it's been shut off.
Said Britt Burt, IIR's vice president of research for the Power Industry, "It sounds as there are days where production of solar power is at a premium, but the power demand is not enough to take the supply. I don't really see this as an issue that will affect the buildout of solar projects. I haven't seen a slowdown per say."
Solar power is actually very useful, supplying almost half of CAISO's electricity demand between 8:00 a.m. and 4:00 p.m. However, as people come home from work and crank up the air conditioner or heat, stoves, etc., demand skyrockets. And on sultry summer evenings the sun sets about the time it's needed the most.
There are some alternatives that could continue to spur wind and solar investments. CAISO is working on several. One is to trade with nearby authorities to sell excess renewable power. Another involves using excess power that would otherwise be curtailed to charge storage battery energy storage systems (BESS).
Also, there's a hybrid solution--using excess solar-generated power to make green hydrogen that could be mixed with natural gas for use in Intermountain Power Project's new facility scheduled to come online in July. Subscribers to Industrial Info's Global Market Intelligence (GMI) Power Project Database can learn more by viewing the project report.
IIR is tracking 78 wind and solar projects in California, totaling about $34.29 billion of investments. Of those 57 are grassroot projects, 19 are unit additions, one is a brownfield project and one is a repower. The latter is the Gonzaga Ridge 100-megawatt (MW) windfarm repower project, which will replace 1985-era turbines with modern ones. The turbine replacement--which is underway and expected to be completed soon--will benefit from newer, more efficient units. (Click here to see the project report.)
The biggest installation, at $3.4 billion, is the Buttonbush PV Solar Center, with a capacity of 2,000 MW. Currently in the planning and permitting phase, its proposed in-service date is May 31, 2028. Subscribers can learn more by viewing the project report.
Industrial Info Resources (IIR) is the leading provider of industrial market intelligence. Since 1983, IIR has provided comprehensive research, news and analysis on the industrial process, manufacturing and energy related industries. IIR's Global Market Intelligence (GMI) platform helps companies identify and pursue trends across multiple markets with access to real, qualified and validated plant and project opportunities. Across the world, IIR is tracking more than 200,000 current and future projects worth $17.8 trillion (USD).
The EIA reports that "In 2024, CAISO curtailed 3.4 million megawatt-hours (MWh) of utility-scale wind and solar output, a 29% increase from the amount of electricity curtailed in 2023."
Of all energy curtailed in CAISO last year, solar accounted for 93%. Curtailment happened mostly in the spring, when, to quote the old song, there was "plenty of sunshine" yet little demand for heat or air conditioning in the mild days of that season.
This might raise the question as to whether the state has reached a saturation point with these renewables--and, if so, would that curtail the installation of new capacity?
In fact, California's renewable power supply has grown exponentially in the last 10 years. The EIA says in 2014 the state had 9.7 gigawatts (GW) of wind and solar capacity. By 2024 the number had almost tripled, to 28.2 GW.
As noted, wind and solar generation only work when there is wind or sunshine. The latter is pretty predictable and regular, the former less so. And when that supply does not coincide with demand, it creates two problems, the EIA points out:
- Congestion, when power lines don't have enough capacity to deliver available energy.
- Oversupply, when generation exceeds customer electricity demand. This is sort of like when there's a downpour after a drought. Getting all that supply at once overloads the system, resulting in flooding. Curtailing renewables prevents the flooding.
That's true, but it's considered to always be necessary in the background, for "base load," and it's harder to ramp quickly, say at sundown or when clouds suddenly hide the sun, if it's been shut off.
Said Britt Burt, IIR's vice president of research for the Power Industry, "It sounds as there are days where production of solar power is at a premium, but the power demand is not enough to take the supply. I don't really see this as an issue that will affect the buildout of solar projects. I haven't seen a slowdown per say."
Solar power is actually very useful, supplying almost half of CAISO's electricity demand between 8:00 a.m. and 4:00 p.m. However, as people come home from work and crank up the air conditioner or heat, stoves, etc., demand skyrockets. And on sultry summer evenings the sun sets about the time it's needed the most.
There are some alternatives that could continue to spur wind and solar investments. CAISO is working on several. One is to trade with nearby authorities to sell excess renewable power. Another involves using excess power that would otherwise be curtailed to charge storage battery energy storage systems (BESS).
Also, there's a hybrid solution--using excess solar-generated power to make green hydrogen that could be mixed with natural gas for use in Intermountain Power Project's new facility scheduled to come online in July. Subscribers to Industrial Info's Global Market Intelligence (GMI) Power Project Database can learn more by viewing the project report.
IIR is tracking 78 wind and solar projects in California, totaling about $34.29 billion of investments. Of those 57 are grassroot projects, 19 are unit additions, one is a brownfield project and one is a repower. The latter is the Gonzaga Ridge 100-megawatt (MW) windfarm repower project, which will replace 1985-era turbines with modern ones. The turbine replacement--which is underway and expected to be completed soon--will benefit from newer, more efficient units. (Click here to see the project report.)
The biggest installation, at $3.4 billion, is the Buttonbush PV Solar Center, with a capacity of 2,000 MW. Currently in the planning and permitting phase, its proposed in-service date is May 31, 2028. Subscribers can learn more by viewing the project report.
Industrial Info Resources (IIR) is the leading provider of industrial market intelligence. Since 1983, IIR has provided comprehensive research, news and analysis on the industrial process, manufacturing and energy related industries. IIR's Global Market Intelligence (GMI) platform helps companies identify and pursue trends across multiple markets with access to real, qualified and validated plant and project opportunities. Across the world, IIR is tracking more than 200,000 current and future projects worth $17.8 trillion (USD).
