Willow Rock Energy Storage Center

Willow Rock Energy Storage Center

The plan

Last month, the Central Coast Community Energy (3CE) signed a 25-year contract with Hydrostor, a Toronto-based renewable energy company that develops utility-scale energy storage facilities, for the construction of a compressed-air energy storage facility. This facility will be located on less than 100 acres, outside the city of Rosamond, in Kern County, CA, and will be known as the Willow Rock Energy Storage Center (WRESC).

Image courtesy of Hydrostor - Early-Stage Willow Rock Artist Rendering

Image courtesy of Hydrostor - Early-Stage Willow Rock Artist Rendering

The WRESC will have the capacity to store up to 500 megawatts (MW) / 4,000 megawatt hours (MWh) of excess generation largely from California solar and wind projects during off-peak hours, or low-demand, by compressing air. This high-pressure air will then be used to provide energy during peak hours (4pm – 9pm), when energy demand is at its highest and renewable energy systems are short in supply. The facility will be expected to provide electricity generation for at least eight hours at full capacity. 

200 MW of the WRESC’s capacity will be reserved for 3CE and will have for goal to meet the demand of their 447,000 customers throughout Monterey, San Benito, San Luis Obispo, Santa Barbara, and Santa Cruz counties, starting in 2028. Hydrostor is aiming to start construction in 2024.

How it will work

Surplus or off-peak electricity from the grid will be used to power air compressors and produce heated compressed air in purpose-built underground caverns. The heat produced during compression will then be extracted from the air and stored in a thermal management system aboveground to be used later in the cycle. 

Once the heat is extracted, the compressed air will be stored in the underground caverns, initially filled with water, where it will force the water up a shaft and into an aboveground reservoir. 

When electricity is needed by the grid, water from the reservoir will fill the underground caverns, forcing the air to be released to the surface, where it will be re-heated using the stored thermal energy, then expanded through turbines to generate electricity.

Image courtesy of Hydrostor - Generic Hydrostor Artist Rendering

Image courtesy of Hydrostor - Generic Hydrostor Artist Rendering

Environmental benefits

By generating carbon-free electricity to meet high-demand hours, without the use of fossil fuels, the WRESC is planned to help achieve California’s objective of 100% renewable energy by 2045. It will also aim to improve grid reliability and prevent blackouts caused by high demand. Additionally, this project will help 3CE meet its goal to serve its customers with 100% clean and renewable energy by 2030. 

As a solar company, we are excited to hear that our customers’ surplus of renewable energy will be used to help power this facility. We are also thrilled that this facility will be a much more sustainable alternative to traditional utility-scale energy storage projects. Indeed, many of these projects use batteries with a Lithium Nickel Manganese Cobalt Oxide (NMC) chemistry, which not only has a high risk of thermal runaway due to the Cobalt component, but is also unethically sourced and has a much shorter lifetime. 

Additionally, this facility will have a decommissioning plan established and approved by the Commission for Environmental Cooperation (CEC). When we asked Hydrostor, they explained that the project will not use or refine heavy metals during the construction or operations of the WRESC. After its 50+ years of expected lifetime, the facility’s equipment will be removed and the site will be rendered safe for future uses. The majority of surface equipment will be suitable to recycle and/or refurbish for placement into new facilities. The cavern and all subsurface access points will be capped consistent with regulations and standards from the mining industry, explained Hydrostor.

What you can do

Energy storage is a key part of decreasing our dependence on fossil fuels and supporting the grid in times of high demand. At the individual level, if you already have a solar system, pairing it with a home battery storage system will allow you to increase your home’s comfort and resiliency while decreasing your reliance on fossil fuels. At Brighten Solar, we decided years ago to only install Lithium Ferro Phosphate (LFP) batteries, which do not contain any Cobalt and have proven to be safe, durable, environmentally friendly, and are an ethical choice. Contact us if you would like to hear more about battery installations!