Santa Fe County commissioners asked AES Clean Energy to explain how the company’s proposed battery energy storage system differs from the Moss Landing incidents cited many times in public comment. The applicant described a suite of passive and active protections, full‑scale lab testing, and what it called several generations of improved architecture.

Why this matters: Opponents cited Moss Landing as a cautionary example; commissioners wanted a technical comparison and asked AES to provide the laboratory reports and modeling that support AES’s claims of reduced propagation risk.

What AES said and what commissioners asked

- Difference in design and scale: AES staff said Moss Landing involved older, retrofit technology in a former turbine hall and included stacked modules in dense racks. The AES representatives contrasted that with purpose‑built, containerized enclosures sized to industry practice; AES staff said the proposed design incorporates mineral‑wool insulation, thermal‑runaway propagation protection, and enclosure features not present at Moss Landing.

- Testing and modeling: AES said it performs full‑scale tests—40‑foot enclosure tests instrumented with hundreds of sensors—then calibrates models to inform spacing and mitigation decisions. AES said it has approximately 1.3 GWh of deployments using the same architecture and that, in its deployments, it has not experienced a field thermal‑runaway event requiring its internal clean‑agent systems.

- Clean agents and PFAS concerns: AES described its internal clean‑agent system as FK‑5‑1‑12 (a clean agent) and noted that aqueous film‑forming foams (AFFFs), which have caused PFAS groundwater problems elsewhere, are a different substance and mechanism. AES asserted FK‑5‑1‑12 is not a PBT (persistent, bioaccumulative, toxic) PFAS and said the agent would only be used in a contained event inside a unit; board members asked for supporting documentation.

- Alternatives such as sodium‑ion batteries: Commissioners asked whether AES had evaluated sodium‑ion chemistry or other technologies as a way to reduce thermal‑runaway risks. AES said it had studied sodium‑ion technology but told commissioners that, based on supplier and laboratory data, sodium‑ion still presents thermal‑runaway and flammability hazards and therefore would require similar mitigation strategies. AES said it would consider new battery chemistries if they proved safer and cost‑effective during the life of the project.

Requests and next steps

- AES agreed to submit the laboratory fire‑test reports and calibrated models used to determine container spacing and propagation risk for county staff and commissioner review before final action.

- Commissioners and several members of the public requested third‑party review of testing data (for example, Sandia National Laboratories or independent labs). AES said it would provide its reports and that the company uses independent experts to review design work.

- Commissioners asked AES whether the company has conducted post‑incident lessons‑learned reviews related to Moss Landing; AES said it has participated in internal lessons‑learned discussions and has evolved product design over multiple generations.

Bottom line: AES maintained that newer containerized designs, field testing and sensor‑based mitigation materially reduce propagation risk compared with the older Moss Landing architecture. Commissioners and staff asked for the underlying test and model documentation and for evidence that the company’s fielded systems have not experienced the type of propagation seen in that widely cited incident.