Exploring Indoor Deployment Technology for Lithium Iron Phosphate Battery Energy Storage Systems

Lithium iron phosphate (LiFePO4) battery energy storage systems (ESS) are becoming increasingly significant in the energy sector due to their high safety risks and complex thermal runaway mechanisms. Traditionally, these systems are deployed outdoors to mitigate safety risks. However, with advancements in safety standards and technology, indoor deployment is emerging as a viable option, particularly in land-constrained regions.

Traditional Outdoor Deployment

Currently, outdoor deployment is the preferred setup for LiFePO4 battery ESS globally. This approach involves pre-fabricated modules that integrate storage batteries, battery management systems (BMS), power conversion systems (PCS), transformers, and distribution facilities. These modules are then transported to the installation site. The outdoor setup offers several advantages:

• Lower safety risks

• Shorter construction cycles

• Flexible and convenient installation

Despite these benefits, outdoor deployment has its drawbacks, such as requiring large areas of land and presenting challenges in maintenance and inspection. This is particularly problematic in densely populated regions where land is scarce. As energy storage stations grow in scale, efficient land use becomes increasingly critical.

Emerging Indoor Deployment

In recent years, some energy storage projects in China have adopted indoor deployment. Examples include the Shenzhen Baoqing Energy Storage Station and the Changsha Furong Substation Energy Storage Station. These projects demonstrate the feasibility of housing storage batteries, PCS, transformers, and other equipment indoors, even for large-scale facilities exceeding hundreds of megawatt-hours.

However, many of these indoor projects initially did not fully meet lithium-ion battery fire safety requirements. Common issues included:

• Inadequate fire hazard classification of buildings

• Insufficient fire zone design

• Non-compliant smoke control and ventilation systems

• Incomplete fire protection facilities

Two main reasons contribute to these safety issues:

1. Lack of Thorough Understanding: Historically, the thermal runaway mechanisms of lithium-ion batteries were not well understood. The industry often considered these batteries inherently safe, leading to lower fire hazard classifications (e.g., Class D in the GB51048-2014 national standard).

2. Fire Safety Acceptance Mechanism: The absence of specific acceptance standards and guidelines for fire safety in LiFePO4 battery ESS led to many indoor systems bypassing fire safety checks.

Advancements in Safety Standards

The industry has made significant strides in understanding and mitigating the fire risks associated with LiFePO4 batteries. New standards and guidelines are being established to ensure safer indoor deployment of these systems. For instance:

• The revised national standard, GB51048, is set to classify lithium-ion battery buildings as Class A or B fire hazards, aligning with other stringent standards.

• The Beijing local standard DB11/T 1893-2021 classifies lithium-ion battery storage buildings as Class A or B fire hazards.

• The Shandong Provincial Technical Guide for Fire Design Review and Acceptance of Construction Projects (Electrochemical Energy Storage Stations), issued in November 2023, specifies that battery rooms must have fire-resistant walls with a fire resistance rating of at least 4 hours, and ceilings and floors with a rating of at least 2 hours.

Future Prospects

With these enhanced safety standards, indoor deployment of LiFePO4 battery ESS is gaining traction, especially in regions with limited land availability or harsh environmental conditions. Notable projects, such as the Guangdong Huning Times Jiangmen (Taishan) Electrochemical Energy Storage Station, are leading the way with extensive indoor setups.

As the industry continues to evolve, indoor deployment of LiFePO4 battery ESS is expected to become a more prevalent and safer option for large-scale energy storage, optimizing land use and enhancing overall safety.