Long Duration 50 kW Energy Storage with Aquifer Pumped Hydro
Antelope Valley Water Storage, LLC
Recipient
Lancaster, CA
Recipient Location
21st
Senate District
39th
Assembly District
$1,584,567
Amount Spent
Active
Project Status
Project Update
The 50 kW Aquifer Pumped Hydro (APH) system is nearing operational readiness. Design and construction tasks have been completed, and the well system has been assembled.
Most of the site preparation is complete, although a few tasks remain, including: interconnection with the local IOU, installation of a solar array, and final inspection of equipment.
This project is now waiting on regulatory approval and permits to operate the system from both the Federal Energy Regulatory Commission (FERC) and Kern County. Work has temporarily been paused until these permits are obtained, and the 1-year operational period and field tests have also been delayed.
The Issue
The increased emphasis on resiliency in the state is driving the need for longer duration energy storage backup capabilities. Longer duration energy storage and energy discharge is needed to respond to unplanned grid outages, curtailment risk, Public Safety Power Shutoffs (PSPS) and to increase renewables penetration. DAC and Low-Income Communities are especially vulnerable to preemptive shutoffs. Many of them cannot afford emergency generators. As wildfires become more common, new energy storage/discharge technologies are needed that provide economical, standalone power when the grid is down.
The California grid is facing three issues that could benefit from longer duration energy storage:
1. Evening Ramp Up: There is not enough power for the grid during the 5-hour evening ramp up (from 4:00 to 9:00 p.m.) as solar goes offline but consumers turn on appliances. The 2-4 hour discharge of lithium batteries has trouble covering the 5-6 hour ramp up period.
2. Public Safety Power Shutoffs: Increased wildfire risks have forced Investor Owned Utilities to shut down transmission lines during high wind events. For example, in October of 2019, power to 800,000 customers (2.5-3.0 million people) was shut off due to wildfire risks. These preemptive shutoffs created major disruptions and may have contributed to at least one death.
3. Overgeneration: In non-summer months, especially in the springtime, there is a glut of solar energy in the afternoons and a dearth of generation in the early evening hours. This creates risks of overgeneration and curtailment of renewables.
Over 90% of the energy storage systems built to date in California use lithium-ion batteries. Excessive reliance on lithium batteries can create materials and minerals shortages, and safety issues from thermal runaway. Also, lithium batteries have a limited lifetime due to the number of cycles that can be performed, typically 500 to 1,500. With daily use, a lithium battery is worn out in about 3 years. Old lithium batteries create a disposal problem. They are also limited to a 2-4-hour discharge, which is not enough to cover the evening ramp up.
Project Innovation
A groundwater storage system will be used to store electrical power. Groundwater will be used to fill surface pipelines. An existing well with 150 kW (200 HP) nameplate capacity will be retrofitted to also act as generator.
At 35% generation efficiency, the well will produce 52.5 kW of power. The technology is behind-the-meter and the addition of solar (needed to start generation when the grid is down) gave us a Net Energy Metering (NEM) interconnection agreement with SCE. For the demonstration, the stored energy will be discharged to provide on-peak power to SCE during the evening ramp up and recharged off-peak.
The technology is both modular and mobile. All the equipment necessary to convert a well pump into a generator (VFD, regen module, valve controls, electrical grid interconnection, monitoring and control equipment) is housed in a shipping container on a trailer. The trailer can be hauled to any well site, connected to the well and the electrical grid to convert a well into an energy storage device.
The project will be operated as follows:
1. 5-hour peak operations: provide 5 hours of electrical generation during the weekday evenings. Ramp up and generation during the evening on peak period for the 4 summer months.
2. Absorb surplus grid power, 10 hours of energy storage: Absorb surplus solar power to reduce chances of curtailment. This will be combined with providing 10 hours of energy storage. Store energy during the 10 daylight hours when the grid may be generating surplus solar energy and ramp up and generate during the evening on-peak period.
3. 100 hours in PSPS event: The project will be operated for 10 days for 10 hours to get 100 hours of generation using black start capability.
The facility will be operated for one year to demonstrate that a minimum of 10-hour discharges can be produced reliably. The regeneration well will be operated to provide at least 50 kW of energy discharge using local groundwater. The test well will be used to demonstrate both the two-way groundwater dependent APH as well as the one-way configuration that stores energy when imported water is available. Using imported water is an added value aspect of this project for DACs and Low-Income Communities that will be negatively impacted by both PSPS and Sustainable Groundwater Management Act (SGMA) events.
Please also see EPC-20-008 project information to better understand the scaling of this technology.
Project Benefits
The proposed project demonstrates a new way to implement pumped storage on a small scale and in a flat area (innovations over previous pumped storage). The project will use a well and a reservoir for stand-alone energy storage. This storage system uses local groundwater to store energy and builds on any aquifer in a distributed network. The motor on an existing well can be repurposed to act as generator to provide a 25-hour discharge duration of 50 kW. The system will be charged (groundwater is pumped, reservoir is filled) during the weekend off-peak or super off-peak hours. Power will be discharged (reservoir water is injected) during the five on-peak hours each weekday. New storage technologies like aquifer pumped hydro will help facilitate integration of distributed renewables and create a path towards state energy goals.
Affordability
Aquifer pumped hydro is estimated to cost less than a lithium ion battery which can lead to lower costs for energy storage and eventually translate to bill savings. This is because it relies on existing infrastructure (wells) and proven technology. It uses durable water wells and pumps that have a long lifecycle.
Reliability
The 25-hour discharge duration can provide peak power during the evening ramp up five days in a row, increasing electric reliability. It can also absorb surplus renewables during the spring period of renewables overgeneration risk.
Key Project Members
Lon W. House, Ph.D.
Subrecipients
3RValve
Match Partners
Antelope Valley Water Storage, LLC
