Renewables in California have met more than 100% of the state’s power needs for hours on end over the past month. The feat is an impressive display of how clean energy can power the world’s 4th largest economy. Now the state needs to build more storage to ensure that solar and wind power can meet even more demand.
The surplus power the state generated over the last month presents both an opportunity and a challenge, since California’s grid is not equipped to manage all of the power generated during peak renewable production hours.
That inability to harness all of the renewable energy resources in the state leads to curtailment — the practice of reducing the output from power generating units when the supply of electricity exceeds the demand, or when grid stability is at risk. It is a common occurrence in many power systems, particularly when dealing with renewable energy sources like wind and solar.
Reasons for curtailment include overproduction — when resources like wind and solar produce ore energy than the grid demands, it can overload the system — or when there’s not enough transmission capacity to transfer all of the renewably generated power to where it’s needed.
While curtailment is important for grid stability, it wastes renewable energy resources and can impact the financial returns of renewable energy projects. When appropriately incentivized, energy storage can alleviate these pressures and improve economics for project developers.
California already has one of the largest fleets of energy storage assets in the U.S., and has set records for its use of battery storage as a power “generating” asset during its record run of renewable power production, but the state could use more — and longer duration — energy storage asests.
The state has rapidly expanded its energy storage capabilities, achieving more than 6,600 megawatts (MW) of battery storage, sufficient to power approximately 6.6 million homes for up to four hours. But the projected need by 2045 is staggering, requiring 52,000 MW to meet its clean energy objectives.
On the frontier of long-duration energy storage, California is making pioneering strides with projects like the $30 million, 100-hour iron-air battery storage by Form Energy. This project is set to revolutionize energy storage with its unprecedented capacity for continuous discharge, which could significantly enhance grid reliability.
In addition, other innovative projects are underway, like the 500 MW compressed air energy storage system by Hydrostor, known as the Willow Rock project. This system stores energy by compressing air using electricity, then releases it to generate electricity when demand peaks. This project is a part of California’s broader strategy to transition to a fully renewable energy supply by 2030.
Further illustrating the scale of development, Pacific Gas & Electric (PG&E) is proposing a new wave of battery storage projects totaling 1.6 GW/6.4 GWh across nine different sites, significantly boosting the state’s storage capacity and enhancing grid management and reliability.
The state’s renewable achievements are impressive and a model for other regions to follow, but the remarkable progress and penetration of renewable energy in the state underscores the need for better and more robust storage capacity to harness it.
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