Page 73: of Maritime Reporter Magazine (November 2015)

shipping hotbed Aalesund who say DC A” which, back at the lab, offers about of its working life, and not even that.” hour of (peak-power) coverage (if not interferes with certain ship operations. 25 percent energy savings. In “Scenario Lindtjorn says ABB is “all-in” when it for tugs). Class have approved a tug’s

B”, the battery is just big enough to as- comes to developing battery power and Bollard pull by battery, so the game is “Dilemma” Solved sist the engines, taking the load at low is working with yards, charterers, own- on. “Basically, the tug dilemma is that you loads and on standby. “B” offers 38 per- ers and designers to “demystify” batter- “We’re only at the beginning of our un- have a need for peak power but only for cent energy savings. “You don’t have to ies and DC Grid. While DNV GL has derstanding of the impact of energy stor- a limited duration. So what do you do,” have a huge diesel engine that’s only re- accepted that peak power can be covered age on vessels,” the Dakar Rally driver asks Lindtjorn rhetorically. ally been put to proper use for 10 percent by a battery, it is understood to want one says.

In the all-electric ABB tug-power and propulsion model, propulsion is con- trolled via variable frequency (speed) drives, or VFD. Engine speeds are in- dependent of propulsion, so the engine can be regulated based on load rather

The heart of a than propeller speed. “With diesel-me- chanical systems, you’re really required destroyer lies to dimension your engine to meet that (peak) power. You can’t say I only need it a fraction of the time, and so I’m not in every vessel going to (put in a large engine),” he adds. With the number of zero-emissions we touch.

harbors set to grow on MARPOL rules, the temptation, Lindtjorn says, is to ad- dress the challenge — at least for larger engines — with a different shaft genera- tor and multiple-engine con? guration, in which case, “You’re still left wanting a little. You’re still required to have mul- tiple engines.” “Now have your engines running on variable speed and making their energy available to the DC system, so you can lose one engine and still use two propel- lers, rather than having to turn on two en- gines every time you start up the boat,” he explains. The DC system makes en- ergy storage available to all parts of the system, so power can be focused on pro- pulsion rather than your AC needs.

“You can go all-electric, turn off all your engines and still have full function- ality. With diesel mechanical you need to think of your minimum speed. That draws a fair amount of power from your engine, unlike an electrically driven mo- tor driven by a converter.”

All that appears to stand in the way of buying an all-electric tug is the avail- ability of charging infrastructure. The exhausting process of choosing a battery type has already been endured by Lindt- jorn and his teams in Finland, Norway and Singapore.

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Commercial vessels may face different challenges than combat ships, but the best vestments requiring a national budget,

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Booth #1560 move back to quayside, you’re operating on only batteries and you can do a bit of charging,” Lindtjorn says of “Scenario www.marinelink.com 73

MR #11 (66-73).indd 73 11/2/2015 4:31:57 PM