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AAWSAP DIRD, Ultracapacitors as Energy and Power Storage Devices, November 2010

U.S. Department of War · 2010-11-01 · 34 pages · text from the file's own layer

This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 1 November 2010. It is one of a series of advanced technology reports produced under the Advanced Aerospace Weapons System Applications Program. The report reviews how ultracapacitors work, how they compare with batteries, their history and materials, and their commercial, military and aerospace uses. It concludes that new materials and cell designs will raise energy density and that the U.S. government must understand the devices' spectral signatures.

From the source:Release of 2026-09-18 Incident: 11/1/10, Las Vegas, Nevada. Released with redactions. 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.

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Figure 6. Ultracapacitor Use in a Forklift. Ultracaps provide energy storage upon descent of a load and deliver
peak power to lift heavy loads in fuel cell powered forklifts. 23
Grid storage management is gaining more visibility as energy conservation and
efficiency are becoming increasingly important. Many utility power sources generate a
relatively continuous supply of electricity. The generated power is matched to expected
use statistics. Daytime use and nighttime rest periods can cause power shortages or
generate unused power if not managed efficiently. This is especially true during the hot
summer months or heat waves, where air conditioning loads can tax a system.
Ultracapacitors can store excess power generated in the night, which can t hen be
delivered when insufficient power is available to match the daytime needs. Distributed
power sources such as wind and solar require a higher level of operational efficiency
with a fluctuating power supply. Wind farms experience power fluctuations due to wind
shear or lack thereof. These spikes in power generation may be wasted on a system ill
equipped to handle the burst of power delivered. During periods where wind may be
lacking, ultracapacitors can be used to help create a more stabilized power supply.
TRANSPORTATION
Earliest uses of ultracapacitors were in motor startup for tanks and submarines. Early
adoption by t he military led to cost reduct ions, which was a critical enabler for
incorporation into diesel trucks and railroad locomotives. Ultracapacitors are find ing use
in transportation in engine startup, braking systems, acceleration, and waste-energy
harvesting. Ultracaps have been placed in ra il cars to generate power for acceleration
and recapture it during braking. In some cases, they are placed alongside the tracks,
and t he power management is hosted by the ra il stations.
The ability to absorb and discharge energy rapidly makes ultracapacitors far better than
batteries for regenerative braking schemes. Most of these applications have been in
public transportation. Regenerative braking can recuperate as much as 38% of the
propulsion energy when used in an ultracap/battery hybrid configuration. Electric hybrid
public buses were some of the first adopters of ultracapacitors for automotive
transportation. These buses also use ultracaps for acceleration, which enables a much
faster acceleration.
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 34 pages are in the text index: search them above, or from the library's search.