The Navy Vol_70_No_4 Oct 2008 - Navy League of Australia
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