UNCLASSIFIED // PUBLIC RELEASERELEASE 06 · SEPTEMBER 18, 2026
PENTAGON UFO FILE · DOCUMENT · DOW-UAP-D147AAWSAP DIRD, Ultracapacitors as Energy and Power Storage Devices, November 2010
This November 2010 DIRD for the AAWSAP program is a practical engineering survey of ultracapacitors, also called supercapacitors. It deals with electrical energy storage. The release’s summary of it mentions no sightings.
Capacitors versus batteries
A battery stores energy in chemical reactions, which hold a lot of energy but release it fairly slowly. An ultracapacitor stores charge physically, on electrode surfaces with very large areas, so it can charge and discharge in moments and survive vast numbers of cycles, but holds much less energy for its weight.
The paper explains those differences, the materials and cell designs that set performance, and the jobs ultracapacitors do best: smoothing out power, providing backup, leveling loads and capturing energy from braking. It also covers the drawbacks: lower energy density, a tendency to lose charge when idle, and the need to manage voltage carefully across cells.
Military and aerospace angle
The paper sees the most credible defense uses in pulsed-power equipment, in missiles and munitions, in support for electric propulsion, and hybrid setups where a capacitor works alongside a battery or generator. That fits other topics in the series that depend on short, intense bursts of energy, such as high-energy lasers and pulsed high-power microwave sources.
The official description
From war.gov/UFO, released September 18, 2026, quoted in full
This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed.
This DIRD surveys ultracapacitors as high-power energy-storage devices and argues that their main value lies in extremely rapid charge and discharge, very long cycle life, and usefulness in systems that need short bursts of power rather than sustained energy delivery. The report explains how ultracapacitors differ from batteries, reviews the materials and cell designs that determine their performance, and emphasizes that they are especially useful for power stabilization, backup power, load leveling, regenerative braking, and other applications where fast energy transfer matters more than total stored energy. It also notes their drawbacks, including lower energy density, self-discharge, and voltage-management requirements that limit their usefulness as stand-alone replacements for batteries in many applications. The document presents ultracapacitors as a maturing and increasingly important technology whose most credible aerospace and military uses lie in pulsed-power, missile and munitions systems, electric propulsion support, and other hybrid power architectures rather than in long-duration primary energy storage.