Power is the most volatile, vulnerable, and pricey line item for data centers. It accounts for approximately 46 percent of total spending for enterprise data centers and 60 percent for service provider data centers.

Between spiking and unpredictable prices, skyrocketing demand for artificial intelligence (AI), and concerns about grid instability, energy has made its way to boardroom agendas. At the same time, utility grids are under unprecedented stress from aging infrastructure and extreme weather.

In this high-risk, high-demand environment, on-site battery energy storage systems (BESS) provide an energy lifeline by ensuring uptime, stabilizing high-density workloads, and helping control energy costs. Here, I’ll explain why BESS is a critical component of the modern data center.

Ensure uptime and resilience, even when the grid fails

Whether downtime lasts milliseconds or minutes, the fallout can be severe: corrupted data, lost revenue, regulatory breaches, or reputational issues.

The Uptime Institute's 2024 Outage Analysis found that more than 50 percent of data center outages cost over $100,000, and a growing share surpass $1 million. Power failures are a leading cause.

When the grid goes down, data centers equipped with BESS can quickly turn on these storage systems to keep important workloads running. Paired with high-efficiency Uninterruptible Power Supply (UPS) systems, BESS provides more protection, ensuring clean, conditioned power during transitions and minimizing the risk of disruption. Unlike diesel generators, batteries and UPS systems require no warm-up time and can support ultra-sensitive systems without delay. Together, they stabilize the local electrical environment, protect against voltage sags, and prevent hardware damage during fluctuations.

Batteries can also enable “islanding,” which lets data centers temporarily detach from the main grid while maintaining full operations. In a world of weather-driven blackouts and grid instability, this flexibility is a benefit for data centers that need to be online 24/7.

To put all this into context, consider a 2024 thunderstorm in Northern Virginia’s “Data Center Alley." More than 60 data centers were disconnected from the grid due to voltage irregularities. The data centers with robust BESS, however, operated independently, avoiding outages and larger grid disturbances.

Support high-density, AI-driven workloads

The explosion of AI and cloud computing continues to change how data centers consume energy and how much they use.

According to the International Energy Agency, global electricity demand from data centers will more than double by 2030, with AI as the main contributor. AI workloads require massive power density and an ultra-stable supply to handle training and inference at scale. A brief dip can crash processes running on thousands of GPUs, wasting computer cycles and upsetting customers in the process.

BESS, together with highly efficient UPS, helps smooth out these sharp, short-term fluctuations, acting as a buffer to prevent load spikes that can stress on-site infrastructure or upstream utility feeds. As cloud and AI energy needs increase, batteries ensure the power system keeps up with demand and protects the data center’s performance and reputation.

When paired with smart circuit breakers and intelligent power distribution systems, operators gain granular control over energy delivery at the rack or cluster level. These systems provide real-time visibility and fast-acting protection, enabling data centers to isolate faults, balance loads, and respond dynamically to shifting AI demands.

Control energy costs and enable renewables

Energy is the largest operating cost for most data centers. Rising utility rates and surging demand charges make matters even more complicated. BESS offers an important cost-control tool that allows operators to:

• Store cheaper off-peak power (from the grid or renewables) and discharge it during expensive peak hours, ultimately reducing demand charges
• Shift loads dynamically based on real-time pricing signals
• Flatten peak usage, lowering contracted capacity needs, and avoiding penalties

Global data centers are also under pressure to integrate more renewable energy into their operations. But solar and wind are inherently intermittent. BESS bridges that gap by turning renewables into dependables – storing excess generation and discharging it when needed. It also minimizes curtailment and helps meet sustainability targets without sacrificing reliability.

Batteries paired with on-site renewables can form microgrids, giving data centers greater autonomy and protection from volatile utility rates. This model is increasingly attractive in regions with constrained grid capacity or where new utility connections are delayed.

New financing models, including as-a-service agreements and performance-based contracts, are also making it easier to deploy BESS without a massive upfront investment.

Batteries are the backbone of modern data centers

Data centers can’t afford to treat batteries as emergency-only assets. BESS helps these power-hungry facilities address energy reliability, cost, and performance. The need for this technology will grow as the world’s electricity demand continues to skyrocket and grid blackouts become more common.

Ultimately, BESS will define which data centers can scale with confidence.