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The Navy Vol_70_No_4 Oct 2008 - Navy League of Australia

The Navy Vol_70_No_4 Oct 2008 - Navy League of Australia

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Lithium-Ion Batteries<br />

Lithium-Ion batteries are used for the USN’s Advanced SEAL Delivery<br />

System (ASDS) seen here piggy backing <strong>of</strong>f the SSN USS GREENVILLE.<br />

Li-ion batteries <strong>of</strong>fer significantly higher power densities over Lead-<br />

Acid batteries and are rugged enough for fleet service. (USN)<br />

<strong>The</strong> weight and volumetric savings <strong>of</strong> the HTS motors make<br />

it possible for diesel-electric submarines to rival nuclearpowered<br />

submarines. <strong>The</strong>y also <strong>of</strong>fer improved stealth and<br />

lower energy loads at partial power. (ONR graphic)<br />

motors/generators <strong>of</strong> similar power. HTS motors are even<br />

more significant for conventional submarines because they are<br />

3-4 times more energy efficient at partial loads. This means<br />

a loitering submarine using less than 30-40% <strong>of</strong> the motor’s<br />

potential shaft power will consume far less energy compared to<br />

legacy motors. This has a significant impact on a conventional<br />

submarine’s indiscretion rate, reducing the amount <strong>of</strong> time<br />

needed to snort. HTS motors are also acoustically quieter and<br />

provide high power densities previously only possible by direct<br />

shafting to a nuclear driven steam turbine.<br />

<strong>The</strong> USN is testing the first HTS motor for installation on the<br />

third Zummwalt class destroyer (DDG-1002). American Super<br />

Conductor (AMSC), a strategic partner <strong>of</strong> <strong>No</strong>rthrop Grumman,<br />

have developed the Zummwalt class’s 36.5 MegaWatt (MW)<br />

HTS motor. AMSC had previously delivered a 5 MW HTS<br />

motor to the US <strong>Navy</strong> in 2003 and are working on HTS concepts<br />

specifically for submarines. Other companies are developing<br />

HTS motors and generators with Siemens having built and<br />

tested a 4 Mega <strong>Vol</strong>t Ampere (MVA) output generator in 2005.<br />

<strong>The</strong>y expect the generator to be available commercially from<br />

2010.<br />

A <strong>No</strong>rthrop Grumman HTS 36.5 MW motor developed for<br />

the Zummwalt class destroyer during production.<br />

Matching the development <strong>of</strong> new motor/generator technology<br />

are significant improvements in energy storage batteries driven<br />

primarily by the consumer electronics market and increasingly<br />

hybrid powered cars. Li-ion batteries currently <strong>of</strong>fer four<br />

times the energy density than lead-acid batteries. With active<br />

monitoring and better cycle durability more frequent charging,<br />

draining and recharging is possible. <strong>The</strong>y can also be packaged<br />

into any shape or cell size. This could enable individual cells<br />

sized for submarine exterior hatches allowing easy change and<br />

upgrade during refit.<br />

Li-ion batteries are currently at sea as the replacement battery<br />

for the <strong>No</strong>rthrop Grumman Advanced SEAL Delivery System<br />

(ASDS) midget submarine. ASDS is solely powered by the<br />

battery that replaces the original silver-zinc unit that failed<br />

to meet the USN’s requirements. Yardney Technical Products’<br />

subsidiary Lithion developed the warship ready, high power<br />

1.2 MegaWatt Hour (MWh) li-ion battery for the ASDS. This<br />

battery weighs only eight tons compared to the 380 tonnes <strong>of</strong><br />

lead-acid batteries on the Upholder class that can only store<br />

around 15 MWh.<br />

Factor in growth in li-ion battery efficiency and the results are<br />

even more staggering. Ultra thin li-ion batteries using nanowire<br />

anodes being developed at MIT and Stanford promise three<br />

times more energy efficiency and commercial availability<br />

within 10 years. If an improved cathode can be found this<br />

could increase to 10 times more energy efficiency. This is a 12<br />

to 40 times energy efficiency gain for weight and volume over<br />

legacy submarine batteries.<br />

<strong>The</strong>re are other new battery technologies <strong>of</strong>fering considerable<br />

improvements over lead-acid batteries. Silver-zinc batteries<br />

<strong>of</strong>fer high energy density but at high cost and limited life.<br />

Rolls-Royce is marketing a molten salt battery using the South<br />

African developed ZEBRA [Zeolite Battery Research Africa]<br />

technology that <strong>of</strong>fers 2.7 times more energy efficiency than<br />

lead-acid batteries. Like li-ion batteries molten salt batteries<br />

are self-contained units that don’t require the maintenance<br />

and emissions monitoring <strong>of</strong> lead-acid batteries. ZEBRA<br />

batteries have been developed to replace lead-acid batteries in<br />

existing diesel-electric submarines and are used in the NATO<br />

Submarine Rescue System (SRS).<br />

What makes li-ion so attractive compared to ZEBRA and<br />

silver-zinc is their use in civilian applications. 20th century<br />

diesel-electric submarines with lead-acid batteries were able<br />

to leverage the massive production <strong>of</strong> these batteries as the<br />

car and truck starter battery <strong>of</strong> choice. For the 21st century,<br />

utilising li-ion provides similar advantages as the constant<br />

growth in demand for consumer electronics and hybrid cars<br />

results in rapid increase in li-ion efficiency and durability.<br />

6 VOL. <strong>70</strong> NO. 4 THE NAVY

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