Supercapacitors can smooth millisecond-scale AI power transients, but experts see them complementing rather than replacing traditional UPS and battery systems.
AI workloads create power swings far sharper than steady-state compute, producing hard spikes that conventional architectures struggle to absorb. Supercapacitors—also called ultracapacitors—sit between conventional capacitors and batteries, storing energy as a surface charge rather than through chemical reaction. This gives them higher power density than batteries but lower energy density, making them suited to short, frequent bursts rather than sustained runtime. Data center operators are testing supercapacitors alongside batteries and uninterruptible power supply (UPS) systems, not as replacements. Batteries and UPS systems still handle sustained load and provide longer backup windows.
A September 2026 IDTechEx report identifies three roles for supercapacitors in data centers: voltage stabilization, peak shaving, and short-term backup power. Supercapacitors charge and discharge in milliseconds to seconds—fast enough to track AI training cycles and recharge before the next spike.
IDTechEx projects the data center supercapacitor market will reach $950 million by 2037, representing a 40.9% compound annual growth rate from 2026. By contrast, total global supercapacitor revenue across automotive, grid, and industrial uses is projected to reach $4.86 billion by 2036, growing 15.3% annually.
The market groups data center supercapacitors into three categories. Electric double-layer capacitors (EDLCs)—the most commercially mature—store charge electrostatically at the electrode surface, much like conventional capacitors. Hybrid capacitors, usually lithium-ion variants, combine an EDLC's surface charge storage with lithium-ion chemistry in which ions shuttle between electrodes. Pseudocapacitors store charge through fast, reversible chemical reactions at the electrode surface, delivering higher energy density than EDLCs but lower power density.
Backup power remains the narrowest application. Typical EDLCs sustain output for approximately two minutes; some hybrids last up to ten minutes—enough to prevent data corruption during brief outages but insufficient to replace a UPS system. Supercapacitors are framed as complementary to, not substitutes for, backup infrastructure.
The market is transitioning from early evaluation to meaningful deployment, though adoption rates vary by technology type and supply chain maturity. "Instantaneous load transients can reach more than 150% of a power shelf's rated capacity during certain AI compute events," said Chris Butler, president of embedded and critical power at Flex. Rack designers are building flexibility to accommodate battery backup units (BBUs), capacitor backup units (CBUs), or mixed configurations. "Supply chain concerns remain a major hurdle, particularly for newer hybrid supercapacitor technologies with limited qualified suppliers," Butler added.
The reliability bar data centers operate under shapes adoption pace. According to Parag Nathaney, principal quantitative engineer for energy policy and power markets at Exelon, the technology must meet 99.999% reliability for the power supply, placing the market in its early stages of pilot and early commercialization. Ian Wright, chief technology officer at DIMAAG, a battery-systems maker, argues that DC-to-DC conversion stage determines response time, not the device alone. "The response speed to load changes is then determined by the DC/DC, which will be slower than either caps or batteries," he said. "If supercaps have been tried and not observed to get hot, that's probably because they are not actually absorbing the cyclic loads."
Wright expects directly connected batteries, not supercapacitors, to become the primary tool for smoothing AI power swings. Nathaney reached a different conclusion: "The long track record of the technology in other applications could lower the barrier for adoption by data centers," he said. Butler is more optimistic. As rack power levels scale from hundreds of kilowatts toward multi-megawatt designs, he expects CBUs to see growing use in managing transient peak demands. Over time, workload-driven optimization will determine the mix of batteries and capacitors, with supercapacitors playing an increasingly important role in peak-power events. "I expect capacitor-based energy storage to become a mainstream element of next-generation AI power architectures," Butler said.