Posed a question to CILT UK now I'm asking you
 

With the current global emissions hitting new heights I had a thought the other night while talking to a good friend of mine about submarines.

It was about how the shipping industry could potentially reduce emissions, and I would like to see what others think about it and if it would be practical in the long term.

Back when I worked on ships (2003-2006) we used to use LSFO fuel oil (Low Sulphur Fuel Oil), the stuff was horrible to handle it was sticky and it stank.
But with the advances in technology the fuel oils used today in ships are much cleaner yet they still produce pollutants.
Some companies have put re burners or scrubbers onto the ships in order to reduce emissions levels but I do think we can go a little bit further.

I spent some time on a VLCC during 2005 that ship used part of its own cargo as fuel, while this was efficient in some respects it was incredibly unclean, however; one of the officers I was with had recently been on a LNG carrier and he informed me that some LNG carriers use the boil off to power the ship.
Not only is that one a smart move but it is relatively clean.

Fast forward to 2014-2017 I spent some intermittent time with the German Navy and visited all 6 of their type 212 submarines, I even went to sea on two of them.
These submarines use an AIP fuel cell system to power the submarine and its hotel load (weapons systems, living systems and sensors).

The boats use hydrogen, Nitrogen and oxygen to create power using a synthetic membrane and electrolysis to cause a reaction which in turn produces power the exhaust product is water.

Now the type 212 is a small submarine yet it carries enough supply to officially last up to 3 weeks of varying use (sorry cant be more specific).
The fuel cell allows this boat to remain submerged for the entire length of the deployment, it does create air and water for the crew, it powers highly sensitive and power demanding systems used onboard.

Cargo ships such as container ships for example do not require the huge hotel loads a submarine does, and it certainly doesn’t need to produce oxygen with reverse osmosis plants and CO2 scrubbers.
Thus if this system was put into a ULCV (Ultra Large Container Vessel) do you think it would be a practical proposition ?

I would be very interested to know the thoughts regarding this subject.

More over in November 2020 DFDS announced plans to construct a fuel cell ferry to work the Oslo to Copenhagen route by 2027

Official communique https://www.dfds.com/en/about/media/...slo-copenhagen

Ferries by nature like cruise ships have a high hotel load due to the carrying of passengers, but cargo ships don’t so would this work?

In a word, no. I'm not an engineer but the size to power ratio of most AIP systems makes them inefficient for large cargo ships. While nuclear power plants on ships is viable, laws, regulations and treaties make that form of propulsion for cargo a non-starter (at this point in time).

@Kapitan theoretically yes, but for the time being this system is much too complicated and expensive; when there is serial production this might change.
I saw that the 212 boats have to be filled up with liquid hydrogenium now and then.
https://defencyclopedia.com/2016/07/...ion-aip-works/

There is 'marine Diesel' in Germany used for yachts and the like, the bulk masses of LSFO fuel oil for freighters is at the very lowest end of what you could call a fuel, it indeed stinks and pollutes everything it comes in contact with.
Problem is not ony the burning and (trying) cleaning the exhaust gases, but that merchants and cruise ships of all nations just flush the tanks with seawater now and then to clean them, releasing the accumulated toxic sticky bottom grime into the ocean. As long as this is 'best practice' the exhaust gases are of lesser concern :03:

The ships i was on most of these were built in the 1970's /80's (except the VLCC she was a mid 90's)
The did mix waste water and oils into the bilge and discharge them over the side.

However I'm reliably told that the new creations post 2005 there's actually no way to discharge anymore, I know the triple E's of Maersk are unable to discharge waste (including oils) over the side and have to offload it in port

To be honest, Kapitan, you probably have a better upstanding of these systems based on your own research and knowledge and experiences than most here. MaDef and Catfish have offered information that seems reasonable. Hydrogen and hydrogen peroxide fuel cells have showed promise and Germany experimented with both during WW2.

Hydrogen has the advantages of low carbon emissions as opposed to fossil fuels. Further, Hydrogen can be combusted directly, or it can be used in a fuel cell to produce electricity.

The dangers of Hydrogen is adequate storage because as you already know, Hydrogen can be volatile. The good news is that scientists are looking for cleaner and renewable energy sources.

I think Hydrogen fuel cells is addition to powerful batteries may be the way to go. Unfortunately, this only seems a viable alternative in the automotive industries.

indeed and both hit on good points too, to be honest im a bit on the fence with this because hydrogen is explosive and we have lost submarines due to hydrogen explosions.

Most ULCVs use a single 30,000hp main engine with 70kw power output to drive the ship and they can reach staggering speeds.
I got a ride on CSCL Glove when she came into Felixstowe on her maiden voyage when we crossed over the North Sea the captain threw her around a bit and at full speed she is capable of 23 knots in a decent sea.
Even for her size she is fuel efficient though capable of 55,000nm one one tank at 18 knots.

It was just a passing thought as DFDS is going for fuel cells in a new ferry in late 2020s just wanting to see views and thoughts on it.