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ALUC 25-09 (Solano County Battery Energy Storage Systems Ordinance)
Determine that Application No. ALUC 25-09 (Solano County Battery Energy Storage Systems Ordinance) which would amend Solano County’s zoning regulation (Chapter 28 of County Code) to revise and update sections pertaining to front-of-the-meter Battery Energy Storage Systems in the unincorporated Solano County, is consistent with the Travis Air Force Base (AFB), Nut Tree and Rio Vista Airport Land Use Compatibility Plans (LUCP).
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RECOMMENDATION:
Adopt a Resolution determining that Application No. ALUC 25-09 (Solano County Battery Energy Storage Systems Ordinance) which would amend Solano County’s zoning regulations (Chapter 28 of County Code) to revise and update sections pertaining to front-of-the-meter Battery Energy Storage Systems in the unincorporated Solano County, is consistent with the Travis Air Force Base (AFB), Nut Tree and Rio Vista Airport Land Use Compatibility Plans (LUCP).
DISCUSSION:
Cal. Public Utilities Code section 21676(b) of the State Aeronautics Act requires the Airport Land Use Commission (ALUC) review zoning regulation changes within an Airport Influence Area.
Project Description
The County of Solano proposes to amend Chapter 28 (Zoning Regulations) of the Solano County Code to revise and update sections pertaining to front-of-the-meter Battery Energy Storage Systems (BESS) in the unincorporated Solano County.
The proposed BESS ordinance establishes comprehensive regulations for battery energy storage systems with a capacity of 1 megawatt hour or greater, including strict siting requirements that prohibit BESS facilities in fire hazard zones, floodplains without flood protection measures, and agricultural zones, while requiring substantial setbacks from sensitive receptors (300 feet for systems with thermal runaway risk). The ordinance mandates extensive safety measures including third-party technical studies, emergency response planning, fire protection systems, air monitoring, decommissioning bonds, and compliance with NFPA 855 and UL 9540 standards, with additional requirements for facilities using battery technologies that pose thermal runaway risks.
In summary, the proposed amendments are in seven parts:
1. Definition and Scope: Adding a definition of Battery Energy Storage System (BESS) as an electrochemical device with a rated capacity of 1,000 kilowatt hours or greater that charges, stores, and discharges energy, applying only to front-of-the-meter systems in unincorporated Solano County.
2. Land Use and Siting Standards: BESS facilities are permitted only in specific zoning districts (Manufacturing and Industrial Zone Districts: M-L, M-G-1/2, M-G-3, I-WD, and IAS) through Use Permit approval, with exclusions from High and Very High Fire Hazard Severity Zones and FEMA-designated floodplains without appropriate flood protection measures.
3. Safety and Setback Requirements: For battery technologies with thermal runaway risks, minimum setbacks include 300 feet from sensitive receptors, 100 feet from front property lines, 50 feet from rear and side property lines, and a 30-foot fire access road. Systems without thermal runaway risk require 20-foot setbacks from all property lines.
4. Technology Assessment and Risk Management: Requiring third-party documentation evaluating thermal runaway risk, comprehensive technology analyses, thermal runaway plume modeling, and hazard mitigation analyses for all proposed battery technologies.
5. Impact Mitigation and Safety Measures: Mandating annual contributions for fire response equipment and training, radio interoperability support, air monitoring systems, comprehensive reporting, and technical studies addressing fire safety, plume modeling, toxic gas dispersion, and impacts to Travis Air Force Base flight paths.
6. Permitting and Review Process: Applications require pre-application meetings, technical review fund payments, Planning Commission recommendation, and Board of Supervisors approval, with extensive building permit documentation requirements.
7. Decommissioning Requirements: Comprehensive decommissioning plans with financial assurance through bonds or letters of credit equal to full decommissioning costs minus salvage value, with manufacturer responsibility agreements for battery cell recovery and recycling.
A copy of the proposed amendments in redline format is included as Attachment C.
Timeline of Public Engagement:
Moratorium Adopted, January 23, 2024: Board of Supervisors approved 1-month moratorium on FTM Battery Energy Storage Systems in the unincorporated County. Moratorium was extended 2 years in February 2024.
Technical Working Group Formed, March 2024: Experts and local stakeholders representing Office of Emergency Services, Fire Protection District Fire Chiefs, Solano County Hazardous Materials, Solano County Agricultural Commissioner, California Energy Storage Alliance, and a member of the public, convened with national experts on best practices for Battery Energy Storage System standards.
Public Workshop, July 18, 2024: Solano County Planning Division hosted a public workshop to gather input on BESS regulations where staff discussed BESS technology, potential community impacts, and Assembly Bill 205's alternative "Opt-In" permitting process. Residents voiced concerns about facility proximity to homes and schools (particularly near the Vaca-Dixon substation), requested taxpayer protections through revenue sharing and independent safety monitoring, emphasized cybersecurity and domestic manufacturing requirements, and advocated for safer battery chemistries like iron flow or graphene over lithium-ion, with many suggesting alternative locations such as Lambie Industrial Park to maintain grid connectivity while avoiding residential proximity issues.
Board of Supervisors Input, August 12, 2025: Presentation on ordinance development and soliciting input on setback standards, agricultural land protection, and standards in Manufacturing and Industrial Zoning Districts. Received direction to amend existing moratorium and proceed with the ordinance adoption process.
Adoption of Updated Interim BESS Ordinance, August 26, 2025: Board Members adopted an Amendment to the Ordinance that imposed a temporary moratorium on the approval of new BESS applications in the unincorporated County. The Amendment allows BESS projects, subject to standards, to be approved through the Use Permit process in Manufacturing and Industrial Zone Districts (M-L, M-G-1/2, M-G-3, I-WD, and IAS). Supervisor Williams requested that technical studies address thermal runaway plume impacts on sensitive receptors in communities near BESS projects and analyze impacts to Travis AFB. Supervisors Mashburn and Vasquez emphasized that Solano does not want to be the ‘County of No’ and the identification of zoning districts that are compatible with BESS projects with standards illustrates that the County does not oppose all BESS projects.
AIRPORT PLANNING CONTEXT & ANALYSIS:
Zoning regulation amendments must undergo review by the ALUC for consistency with the applicable LUCPs. The proposed regulations will apply to the unincorporated areas of the County of Solano, and staff evaluated the proposal using the compatibility zone criteria for Travis AFB, Nut Tree, and the Rio Vista Airport Land Use Compatibility Plans as it applies to the unincorporated area.
Staff evaluated the County’s proposed ordinance against applicable Compatibility Zone Criteria. The proposed amendments do not affect regulations related to flight hazards such as structural heights of objects, hazards related to bird attraction, electrical inference, glare and other flight hazards.
Of particular importance to airport compatibility, the proposed BESS ordinance specifically requires technical studies to address impacts to Travis Air Force Base and all other County airport flight paths, and mandates comprehensive safety measures including fire protection systems and emergency response planning that could affect airport operations. The ordinance restricts BESS facilities to Manufacturing and Industrial zoning districts and requires substantial setbacks and safety measures that help ensure compatibility with airport operations.
Analysis Finding
Based upon review, staff finds the proposed changes are consistent with the Travis AFB, Nut Tree, and Rio Vista Airport Land Use Compatibility Plans.
ATTACHMENTS:
Attachment A - Compatibility Criteria
Attachment B - Compatibility Zone Map
Attachment C - Proposed Ordinance - Redlined
Attachment D - Draft Resolution