AUVAC

DARPA Blue Wolf Program

The Blue Wolf program will develop and demonstrate an integrated underwater vehicle capable of operating at speed-range combinations previously unachievable in fixed-size platforms, while retaining traditional volume and weight fractions for payloads and electronics.

The Blue Wolf program will focus on rapid testing and maturation of novel energy, hydrodynamic lift, and drag reduction technologies, which will be developed and tested at-sea to confirm maturity and performance. Blue Wolf will modify existing hardware and systems to establish the vehicle baseline (a “reference vehicle”), and will seek technical solutions to achieve the program metrics specified in the classified addendum.

How ultracapacitors work (and why they fall short)

Hang around the energy storage crowd long enough, and you’ll hear chatter about ultracapacitors. Tesla Motors chief executive Elon Musk has said he believes capacitors will even “supercede” batteries.

What is it that makes ultracapacitors such a promising technology? And if ultracapacitors are so great, why have they lost out to batteries, so far, as the energy storage device of choice for applications like electric cars and the power grid?

Put simply, ultracapacitors are some of the best devices around for delivering a quick surge of power. Because an ultracapacitor stores energy in an electric field, rather than in a chemical reaction, it can survive hundreds of thousands more charge and discharge cycles than a battery can.

A more thorough answer, however, looks at how ultracapacitors compare to capacitors and batteries. From there we’ll walk through some of the inherent strengths and weaknesses of ultracaps, how they can enhance (rather than compete with) batteries, and what the opportunities are to advance ultracapacitor technology.

ONR BAA 11-016 Long Endurance Undersea Vehicle Propulsion

The Office of Naval Research (ONR) is interested in receiving proposals for an energy dense air –independent, rechargeable/refuelable energy system for a long duration unmanned undersea vehicle (UUV).

The goal of this program is to develop and demonstrate power system technologies capable of the performance specifications and characteristics contained in Tables 1-3 with the purpose of transitioning the technology to the Navy. Proposals shall describe a complete system concept, provide a detailed scope of work for the development of the core technology(ies) and conduct integrated bench-top system testing to achieve a Technology Readiness Level (TRL) of no less than 4 (Phase I Base). In addition to the specific S&T performance capabilities, proposers are expected to conduct a safety analysis of the system energy technology concept. Any proposal that does not provide a specific full system solution, as well as a safety analysis, will not be considered.

PLEASE NOTE: NUCLEAR POWER OPTIONS WILL NOT BE CONSIDERED FOR THIS EFFORT.

Program Plan:
It is anticipated that awards will be in the form of cost-type contracts, specifically Indefinite Delivery/Indefinite Quantity (IDIQ) contracts with cost-type Task Orders under those IDIQ contract vehicles, with the evaluation criteria provided in Section V of this BAA.

The three (3) planned phases, Phase I Base, Phase I Option, and Phase II, are covered by this BAA, and the objectives for each are described below. Only full technical and cost proposals for Phase I Base and Phase I Option are being requested at this time. However, consistent with the BAA requirement for a full system description, proposers must include a preliminary description of their anticipated Phase II effort together with a ROM Phase II cost estimate. Decisions for continuation to Phase I Option and Phase II will be based on the degree to which Phase I Base results meet key metrics as described in the following section below and the proposed path to achieve objective metrics.

Response Date: 16 May 2011

Energy Storage for long endurance AUVs

Energy Storage is a key Issue for Long Endurance autonomous underwater vehicles. Mission duration, speed through the water and sensor and payload capabilities are constrained by the energy available, which in turn is governed by the characteristics of the energy source or sources and the mass and volumn that the vehicle designer can devote to the energy system. Tensioned against these technical issues are those of cost, operational life, ease of use, maintainability, safety, securty and continuity of supply of the items forming the energy system. This paper focuses on primary and secondary electrochemical batteries, how existing vehicles have constructed their energy storage systems and seeks to establish whether electrochemical cells alone will be able to provide the necessary energy at an affordable cost for future long endurance AUV’s and the missions being considered.

Long-Endurance Test Results of the Solar-Powered AUV System

The solar-powered autonomous underwater vehicle (SAUV) was designed for long-endurance missions, such as monitoring, surveillance, or station-keeping, where real-time bidirectional communications to shore are critical. In April 2006, the Naval Undersea Warfare Center (NUWC) Division Newport, Falmouth Scientific Inc. (FSI), and Autonomous Undersea Systems Institute (AUSI) conducted a 30-day, long-endurance test using SAUV II primarily to demonstrate that the vehicle is capable of conducting long-term oceanographic data collection and to validate the vehicle’s mechanical integrity. This test also served to evaluate possible anomalies and risk-reduction measures for future production-level vehicles.

A key part of this long-endurance test was the logging of the SAUV II charge and discharge rates under different sky and weather conditions with the vehicle under varied energy load situations—data that can be used to assess vehicle endurance and help establish future mission capabilities of the SAUV II. This paper describes the SAUV II test vehicle, test methods, data collected, and the results of the long-endurance test.

MODELING HYBRID ENERGY SYSTEMS FOR USE IN AUVS

Specifying an energy source for an AUV is usually a compromise between performance and cost. For most vehicles and most missions, high specific energy primary lithium batteries are not a practical option due to cost. One solution that shows promise and affordable cost is to use a hybrid approach that combines low cost secondary batteries with a fuel cell or combustion energy source. Exploring the design space for these more complex energy systems requires suitable tools for modelling and assessment. One such tool is Virtual Test Bed. To build confidence in the tool, its simulations have been assessed against experimental data for 18650 lithium ion cells and a Ballard fuel cell, with encouraging results. Subsequently, a conceptual design for a lithium ion battery and fuel cell hybrid energy source was modelled and the performance of two variants assessed for two different 7-day mission scenarios. In both cases, the hybrid system exhibited a specific energy comparable to primary lithium manganese dioxide batteries, with full account taken for the mass overhead of realistic reactant storage for the fuel cell.

Solar Powered Autonomous Vehicle Development

To meet the rapidly expanding requirements for Autonomous Underwater Vehicles (AUVs), Falmouth Scientific, Inc. (FSI) is working in cooperation with the Autonomous Undersea Systems Institute (AUSI) and Technology
Systems Inc. (TSI) to develop a vehicle capable of long-term deployment and station-keeping duties. It has long been considered that AUV platforms, in-principle, could provide an effective solution for surveillance (security and
anti-terrorist), environmental monitoring and data portal (to sub-sea instruments) requirements, but limitations in battery life have limited AUV usefulness in such applications. The concept of a vehicle that would allow on-station recharging of batteries, using solar cells, has been presented as a means to significantly enhance the effectiveness of AUV platforms where long-term or ongoing deployment is required.

The Solar Powered AUV (SAUV) is designed for continuous deployment (weeks to months) without requirement for recovery for service, maintenance or recharging. The SAUV under development is designed as a multi-mission
platform to allow payload configuration by the end-user to optimize the SAUV for coastal/harbor monitoring, data portal (to moored sub-surface instruments) applications, or any other application where long-term deployment is
required. The SAUV is designed to reside on the surface while recharging batteries and then to execute its programmed mission. While on the surface the SAUV is designed to communicate via Iridium® satellite or RF communications link to upload collected data and to allow reprogramming of mission profiles.

Development of the SAUV has generated numerous engineering challenges in design of the solar recharge system, design of a propulsion/direction control system capable of handling the unique shape requirement, design of the telemetry system, and development of mission control algorithms that include surfacing and battery recharge requirements.

This paper discusses the details of unique SAUV design requirements, specific engineering solutions for hull, panel, battery, communication, charge control, navigation,

TECHNICAL ISSUES AND OPPORTUNITIES FOR FUEL CELL DEVELOPMENT FOR AUTONOMOUS UNDERWATER VEHICLES

The efficiency and quietness of fuel cells make them attractive power sources for the autonomous underwater vehicles of the future. However, several technical issues must be addressed before fuel cells can surpass the performance characteristics of batteries, including efficiency, reliability, durability, standby operation and storage, changes to orientation, and high shock loads. Improvements to the storage of the fuel (hydrogen or hydrogen sources) and oxidizer (oxygen) make the biggest impact on the size, weight, and utilization of fuel cell systems. Proton-exchange membrane fuel cells (PEMFCs) are the most attractive fuel cell system and already have been successfully demonstrated for use in Autonomous Underwater Vehicles (AUVs). AUVs of the future may utilize direct methanol fuel cells (DMFCs) or solid-oxide fuel cells (SOFCs) which can use liquid methanol or diesel fuel instead of hydrogen.