Containerised Battery Bank

This article has a better explanation than the Splash article.

The system uses waste heat to charge the battery and the power is used to augment the ship’s generators

It’s said to reduce maintenance on the generators as it provides both peak power for example when using the bow thruster and for redundancy. A lot of generator hours are run up just providing redundancy, for example the second generator that is run in pilot waters or the third generator run to supply power for peak bow thruster operation.

The WHB is putting excess heat into your CFW through the steam dump condenser, or you’re using your bunker tanks as steam dumps. Not as effective as one would like when the sea temp is 30 C.

Steaming at slower speeds (eco speeds) gives more steam. The more speed/load means more scav air which means cooler temps in your WHB.

Instead the excess steam energy is converted and stored in a battery bank that gets used for a bow thruster/big loads.

According to a Danish instructor (MAN class) I had, there is no such thing as “surplus power”. He said on the Triple-E class ship he sailed on, the steam created in the waste heat boiler was passed through a steam turbine generator. This produced not only enough power to carry this ship’s load (including reefers), but also sufficient power to feed into the propulsion shaft via a shaft motor/generator. This allows the same shaft RPM with a lesser ME fuel rack setting. A similar setup is shown here:

WHRS ST-PT.pdf (65.0 KB)

(This setup actually goes a step further and includes a power turbine right off of the exhaust manifold.)

There is no free lunch. If there is power being consumed to charge batteries then that power could be used to power other things which instead are having to be powered by the ship’s generators.

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At higher load it’s true that the TC is extracting more energy from the exhaust (and thus exhaust gas inlet temps to the WHB are lower), but the flowrate of gas more than makes up for it. (at least on my ship). This can be seen by the position of the steam dump at Nav. Full vs. some lower bell. Dump is more open at higher bells.

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This is very true and would be a very useful use for this system. Is there a CFR requirement to run two generators while maneuvering or is it just done because it’s the smart thing to do? If it is required, would a battery bank satisfy the requirement?

Look, I don’t need convincing. I already happen to think that hybrid power systems are hella cool, and even designed one or two, but that’s beside the point. Sort of.

I’m reacting to the ‘Together we synergize visions and technology to make the future carbon neutral, building a greener globe for the children of tomorrow!’ type of drivel that gets mixed in with the science. The notion that battery powered load peak mitigation has anything to do with going carbon neutral is utter bullshit.

In a word…No.


All of these feel good initiatives are dreamed up by public relations arms of these corporations to have a “green” message when challenged on what they are doing to combat climate change.

I appreciate the input from several of you regarding how this battery is to be charged, and converting waste heat or other energy to electricity to be stored in the battery seems an excellent idea, albeit somewhat trivial in the big picture of powering the vessel.
It strikes me that none of the folks peddling batteries (in both land- and sea-based applications) seems to be even slightly interested in discussing the lifetime costs (both financial and environmental) of the things - as we all know, batteries are:
a) not forever - they wear out and must be replaced/remanufactured at some point;
b) consist of some quantity (usually large) of heavy metals, which are generally, if not universally toxic; and
c) have significant potential for “unplanned” energy release (see the Norwegian ferry story of a few weeks ago).

All of these things bear on the lifetime costs, and need to be included in any analysis - all the nice fluffy “eco-friendly” words to the contrary.


Maybe, on the other hand nobody knows exactly what technological path will prove to be the most viable in the future. Maersk is a big company, it might be a smart strategy to have some in house expertise in various potential possibilities.

Actually installing this system on a ship is going to give Maersk some expertise in battery technology all the way from CEO to ship’s crew.


Running a MAN 60MC with RPM from 0-99 I get more steam at 70-75 than I do at ~85. The lack of scav pressure (the blowers cycle off on pressure around 83) means I get 400 C exhaust temps at the 70 RPM range.

As soon as the boost picks up my steam pressure falls off a bit, following the exhaust temperature.

I keep steam pressure, JW in/out, RPM, scav temp, and mean exhaust temp pulled up on a trend during maneuvering/run up/slow down.

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On a RORO with the ability to start cargo fans from the ECR, we used them to load up the generators a little during maneuvering. On the ship without the ability to start cargo fans from the ECR we ran our 1100 KW generators at 200 KW… Would be nice to have the ability to load them up and save the power for something else.

I hate idling 3 generators, that get pushed up to 60% for a few seconds (bow thruster) while the deck dept figures out how to tie up.

Nothing to do with powering the vessel on batteries alone. Just making better use of our equipment hours and maintenance.

It has not yet got to where battery banks installed on large container ships and RoRos are common. Where it is presently being used is on offshore vessels and short haul vessels, like ferries etc. where it makes a lot more sense.
Maersk is trying out many different options and not to score PR points, but because it makes good business sense.
If that scores some browny points along the way so much the better.

Ah, that. I wonder how this would look at full scale?

I’m thinking those guys need to go to firefighting school… But a good illustration of how stored energy can go sideways sometimes.
Maybe this is why Maersk thinks putting the battery in a container is a good idea? So you can eject the whole thing if needed?

Hmmm… lithium / water explosion at depth right next to the hull side? Sounds like a good way to sink the ship… What you saw in that video was a few pounds of batteries going up. If a 40 footer full of the things decides to go off, I think all the king’s horses and all the king’s men could pretty much forget about it.

Containerization just makes a lot of sense from the logistical perspective, from manufacturing this thing, moving it around, lifting it on board, securing it in place, storing replacements, managing modularity, etc. With the right circuitry in the box, you could conceivably drop it in the stack with the rest and plug it right in a reefer bus. Pretty clever, to be honest.


Yes, you’re probably right - not something you want to dump in the ocean right next to you =8^O

I found this article that discusses the environmental cost of batteries - in their case, EV batteries, but essentially the same problem on a slightly smaller scale. Vice article

True. But current fossils fuel usage has none of these disadvantages?
Both fossil fuel use and battery technology will become more efficient with less energy waste once politics gets out of the way. Their are engineers that love to innovate and make things more efficient. Efficiency in any engineering endeavor is taught as a core tenant of the profession.

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Lessons learned from Foss’ experiences are worth reading:

It reads to me that battery assisted power is worthwhile during short term high demand (like mooring).
Their discovery of electro magnetic interference messing with smart charging seems significant. Other findings seem intuitive now, like keeping battery banks separate from everything else, keeping them cool, and accommodating potential fire and explosion.
I think the Campbell and the Dorothy Ann have been running fine.

The report clearly confuses cells and batteries, as the largest cell that Kokam (Kokum is a misspelling) show on their website has 240 amp-hours capacity at presumably around 3.7 VDC, giving about 900 watt-hours. There is no way that Carol Ann is using enough individual cells in series to meet the energy/power demands as that would mean supply voltages of many kilovolts DC.

Kokam’s in-house marine batteries are water cooled 74VDC, 10.3kWh. each using two series strings of twenty cells of 70 amp-hours each.

That particular cell doesn’t seem to correspond exactly with any of their listed ones (optimized differently via differing chemistry) but should weigh between 1.1 and 1.9 kg with dimensions between 226x2275x12.3 mm and 268x265x13.7 mm. The cells are of pouch construction, broadly similar to the Polapulse flat carbon-zinc batteries that Polaroid built into film packs for their electrically operated cameras.

So two sets of fourteen Kokam batteries in series in the Dorothy Ann means they’re running the system at one kilovolt output which seems more reasonable. That would give a total capacity of both strings of about 390 horsepower hours at quoted capacity and neglecting losses.

Obviously if the contractors were assembling their own batteries the numbers would be different. 400 hp-hours seems small to me so I imagine that was the case. But my point is that any practical system using Kokam cells will have many many cells in parallel, even if the batteries were all connected in series.

Incidentally Kokam say that one of their cell types could put five megawatt-hours into a forty foot trailer, and another one three MWh.