electric vs gas theory

[Ianhill]

I even heard that because progress was so slow on the rockys that they took a team of chinnese dismantled a loco and a rew wagons and manually carried them over so they could progress at better speed truly crazy stuff went on, the Irish are a cracking bunch but don't get them pissed or like you said introduce the north to the south while your within a few miles of them.

 

[Hillhater]

The deltic that was used in the diesel electric trains was two engine blocks back to back for 36 cylinders in triangle formation with 3300hp and god only knows the torque figure some steam trains where 7800hp and rated for 5000 tons but modern electric trains and this is a electric forum after all can top at at a staggering 18000hp now that's why electric is king if you can feed it the power in a reliable continous fashion.

18,000hp ..is king ?? :lol: Thats hardly even a "little princess" to the 100,000+ hp 2 stroke Diesels in modern container ships !!
And as i said earlier , its going to take something very cleaver for an electric drive to replace those !

 

[Ianhill]

The deltic that was used in the diesel electric trains was two engine blocks back to back for 36 cylinders in triangle formation with 3300hp and god only knows the torque figure some steam trains where 7800hp and rated for 5000 tons but modern electric trains and this is a electric forum after all can top at at a staggering 18000hp now that's why electric is king if you can feed it the power in a reliable continous fashion.

18,000hp ..is king ?? :lol: Thats hardlt even a "little princess" to the 100,000+ hp 2 stroke Diesels in modern container ships !!
And as i said earlier , its going to take something very cleaver for an electric drive to replace those !

I agree the new container ships are so efficent that it costs less to get a parcel say half way around the world to your country than from the port it arrives at to your house in most cases so theres no call to increase thier efficency yet we still have plenty diesel to keep them running for a good few year yet, but try send that same container ship diesel engine down a standard gauge railway when it's 3 story's tall and the weight would buckle even forged tracks then the 18000hp the electric motor makes per kilo of its own weight makes sence then as it's compact and light like a little princess but packs a decent punch

Here's a navy 50000hp electric.
View attachment 1

Heres a 110000hp diesel.


There's a slight size and weight difference 75 tons vs 2300 tons for the diesel the crank alone is 300 ton but both used together could power a large city if not more over 35Mwh on full crank is needed for the electric not sure on what the diesels equivelent hour usage but it's going to be alot more than double 35Mwh it's proberly around 100Mwh when u convert the work done if it's at full tilt, it's only so cheap to move things as the weight on board is just purely silly numbers just over 19000 containers full to the brim and enough fuel on board to go for twice around the world if full.

 

[Hillhater]

Use of big marine diesels is not just about efficiency and operating cost, but practicality...it just cannot be done on electric drive alone. !
Assuming those big ships need the 100,000 hp, (for at least some of the time), whilst its. Perfectly possible to have electric drives Of that output , supplying the energy to power them is a little less "green"
The normal solution for big cruise ships, ferrys, etc, is to use the big diesels to drive generators to supply the power.
(QE2 had nine of those big 2 stroke diesels driving gensets), though i guess nuclear is also an option.
There are no power lines, or recharge options across the Pacific.

 

[Ianhill]

Use of big marine diesels is not just about efficiency and operating cost, but practicality...it just cannot be done on electric drive alone. !
Assuming those big ships need the 100,000 hp, (for at least some of the time), whilst its. Perfectly possible to have electric drives Of that output , supplying the energy to power them is a little less "green"
The normal solution for big cruise ships, ferrys, etc, is to use the big diesels to drive generators to supply the power.
(QE2 had nine of those big 2 stroke diesels driving gensets), though i guess nuclear is also an option.
There are no power lines, or recharge options across the Pacific.

Correct the read up on the qe2 said they used the setup so they could sit idol for longer periods of time that's the only time the efficency increase is worth while so with cargo ships designed to be in constant use there's just no need for complexity.

You don't get to have a luxury hybrid cruise ship named after you unless your the queen then you get your own personal assassins and only wipe with the finest £50 notes what a life i woinder does she realize the engineering marvel powering her double ganger the queen starting busting out facts and development technical issues.

 

[Hillhater]

Efficiency would go down if electric drive is used due to the conversion losses .
From what i can see,the main reasons the cruise ships use the "Hybrid" drive is reduce noise and vibrations , provide a high degree of manouverability ( Electric "Azipods") , Power supply security/redundancy, and simplicity of power distribution fo the various heavy electric demands on a passenger filled cruise ship.
Its like the different approach between a truck and a luxury motorhome.

 

[Ianhill]

Those azipods are very handy for a vessel that needs a good change of direction or even spin on the spot cracking bit of tech.
Bang on about the ships power for communications etc but the efficency gains are only worth having if like mentioned when very little work is being done stalking a vessel etc, the engine still runs the ships power generators etc so it's just as easy to make it a diesel electric then generate and distrubte power as it's needed very little waste.
Straight out of GE for the next 2020 uk navy fleet :-
https://www.gepowerconversion.com/inspire/royal-navy-and-next-generation-frigate

The use of electrification, which is becoming the de facto standard for propulsion and marine services in the Navy, also provides additional energy saving potential, reduced running hours of generators and can provide flexible power reserves for transfer to weapon and sensor systems if necessary.

Electric propulsion is also useful when a ship is required to remain on station at slow or ‘loiter’ speeds for long periods. The motors will operate at very low powers in these conditions only drawing a small amount of power from the ship’s electrical service system providing good overall system efficiency. Saving fuel not only saves money and reduces emissions but it increases range and allows the ship to be more operationally effective.

 

[Hillhater]

But you still have to run the generators constantly for all electrical aux services.
Most ships have a range of different size generators that they can select or mix to provide the level of power demanded.
Aux generators for lighting, pumps, etc, will always be separate from the main propulsion gensets.

 

[billvon]

But you still have to run the generators constantly for all electrical aux services.
Most ships have a range of different size generators that they can select or mix to provide the level of power demanded.
Aux generators for lighting, pumps, etc, will always be separate from the main propulsion gensets.

No reason it has to be. As drives evolve, we will get to the point where one large, efficient engine generates all the power needed by the ship - with smaller auxiliary generators providing emergency power for auxiliary services (and even emergency propulsion.)

 

[Hillhater]

First rule of ocean shipping...
Never have all your eggs in one basket !
Generally ships have dual or back up systems for everything.
You wouldnt use a single 80MW generator if you had the space for 2x 40MW , or 4 x 20MW.

 

[Ianhill]

I'm going to try and look further into the design i know they won't leave a navy vessel without power a sitting duck so I'm interested to see what the redundancy is, Does the diesel run with pistons shut down can the generation happen at more than one point etc what does it take to put such a ship out of action surely they have one of the most reliable system one would of thought if ships of past had such a strong simple setup why step backwards? But it does happen in some cases new is not always best.

 

[Hillhater]

Type 26 will use multiple drive technology..
Gas turbine , ..direct drive.
Dual electric motors, powered from muliple Diesel generator sets.
From Wiki..

..The propulsion system of the RN ships will have a gas turbine direct drive and four high speed diesel generators driving two electric motors in a combined diesel-electric and gas (CODLOG) configuration.[8][49] In 2012 Rolls Royce repackaged the MT30 used in the Queen Elizabeth class aircraft carriers so that it would fit into smaller ships.[50] The MT30 will be used in the Type 26.[51] BAE Systems have suggested that some customers will install gas turbine engines and others will prefer to sacrifice 2–3 knots of speed by choosing cheaper diesel engines.[26] The choice of CODLOG configuration for propulsion is somewhat surprising[citation needed] as it is a simpler version of the CODLAG propulsion used on the Type 23 which this ship is to replace, and both of the Global Combat Ship's design contemporaries – the Queen Elizabeth-class aircraft carrier and the Type 45 destroyer – use integrated electric propulsion (IEP)......

More explanation here..
https://en.m.wikipedia.org/wiki/Integrated_electric_propulsion

 

[Ianhill]

View attachment 1


Diagram of the new system in place plenty of complexity but there's also alot of separation and redundancy perfect for a war vessel.
Cheers for the info tip off hillhater thumbs up.

 

[Hillhater]

i dont fully understand why they have chosen to use the direct mechanical coupling between the various motors ( turbine and electric) and the prop shafts. Thats a lot of gearbox losses and maintenance etc to deal with compared to using a full series hybrid drive with all electric propulsion motors and a mix of generator systems. ( as the type 45) ?
It also makes the installation more complex and "noisy" with much of the propulsion gear rigidly fixed to the ships hull. Not what i would want in a modern military vessel.

 

[Ianhill]

I downloaded a energy density chart but it doesn't load up on here so you can Google that 700 bar hydrogen is extremely energy dense for the space it takes up and it also well priced for a vessel to take advantage of its location in the world and fill up in what ever convenient way suits.
I imagine the gas turbine is fed from the 700 bar hydrogen tank so the space it takes up is perfect for condesing a system like the design goal was but like yourself I see a little extra complexity around the gas turbine coupling and it's only capable of assisting drive not generation.
I feel this setup can still be improved upon, but even if the gas turbine was directly coupled to its own prop it would still need to go through its own reduction so the design it's quite innovative in some respecs to its predecessor as it was one or the other as this design allows all power at once for ripping acceleration.

 

[Hillhater]

I doubt the navy would use compressed hydrogen as a fuel.
conventional marine "Gas Turbines" run on various fuels, including LNG etc, but aviation type fuel ( Kerosene) would be most likely, thought they would probably choose a common fuel that suits the Diesels also.

 

[billvon]

i dont fully understand why they have chosen to use the direct mechanical coupling between the various motors ( turbine and electric) and the prop shafts.

Speed. You can pass a lot more power through a driveshaft than through a generator/inverter/motor in a similar volume.

 

[spinningmagnets]

I doubt the navy would use compressed hydrogen as a fuel

There's a process that works, and is in prototyping where the massively excess electricity available to an aircraft carrier is used to take fresh water and electrolyze it into hydrogen and oxygen (a very simple process, but has poor efficiency). The oxygen is vented away (as far as I know) and the hydrogen is run through a process that takes carbon dioxide and results in a synthetic kerosene (JP5?).

Cost per gallon is horribly expensive, but...as long as they can make hydrogen and have access to carbon in some form, they can make as much aircraft fuel as they need.

I wouldn't be surprised if they started making small disposable hydrogen-lifted blimp-drones to provide un-manned "one way" over-the horizon intel. One of the small disposable camera-drones they recently used had a clever tiny air-cooled Wankel that ran on JP5, turning a propeller.

 

[Dauntless]

Dang, you guys are making me want to drive down to San Pedro and find out if there's any tours of the big ships and their drive systems. I've been on the Queen Mary tour, it didn't used to go in the engines. They might not be there anymore.

 

[Ianhill]

Very interesting read :-
https://www.rina.org.uk/Project_Napier_sees_twin-track_plan_adopted_to_resolve_Type_45_problems.html

I remember hearing issues arising with this on the news funnily enough but never really took any notice or reaeearched the design.

The problem seems to be the propulsion system knocking out the complete ship electrics. who designs these thing don't they brainstorm as a group ?
I guess if the generator were idling or not all active and a large motor torque is asked for with out the gas turbine singing the whole ship would black out, With no battery etc to supply the instant demand the generators were over whelmed and have had to go into revision, the whole project is a massive waste of tax resources, these days engineers miss the basics with modern innovation and complex wizardry that good old grunt would wrestle to the ground.
The outcome is trying to build in so much redundancy is now gonna cost them a shit load of headaches in software and power compromise in some demanding sitations were they were trying to scrimp on energy so it ends up not being as efficient as claimed.

 

[Ianhill]

My local steel works create lpg as a by product and sell it to costumers for hydro cars not sure the demand just yet if any.

Hydrogen is inefficent to make then run through a inefficent fuel cell to give elector for a car so battery's will always win in that respect but if we run a modern large scale gas turbine with the stuff then the range would (or should I say could :lol: ) be significant specially if high preasure or liquid hyrdrogen was stored,
After reading up on the design there's 2 × 20Mw gas generators + 4× 2Mw diesel generators and they normally run the ship with 1 gas turbine and 1 diesel generator the link above states how poor the integration was between the separation good idea poor implementation.

 

[Chalo]

I downloaded a energy density chart but it doesn't load up on here so you can Google that 700 bar hydrogen is extremely energy dense for the space it takes up and it also well priced for a vessel to take advantage of its location in the world and fill up in what ever convenient way suits.

Holy crap. Enough hydrogen gas to propel a container ship or warship across an ocean, pressurized to 10,000 psi. I really don't want to be in the same time zone as that.

 

[Ianhill]

I downloaded a energy density chart but it doesn't load up on here so you can Google that 700 bar hydrogen is extremely energy dense for the space it takes up and it also well priced for a vessel to take advantage of its location in the world and fill up in what ever convenient way suits.

Holy crap. Enough hydrogen gas to propel a container ship or warship across an ocean, pressurized to 10,000 psi. I really don't want to be in the same time zone as that.

Tsar bomb cruise ship to Mars ? Haha I'm sure they won't be using the hull plugged with hot lead, sugar and ox blood mix,
Say it's average consumption is 21Mw then a gas supply is gonna be fairly large may as well squish it a bit more.

At 1 bar a euro coin would have 1.5kg of force acting on it at 700bar it has 1.2 tons of force over the same area.

Elon musks gas chamber from the space x rocket stored inside a war ship would escape the solar system before it run out of fuel it it would also break earths orbit if it ever went tits up.

 

[Hillhater]

It seems that these Hybrid propulsion systems are proving problematic for other Navys also..
https://www.defenceconnect.com.au/maritime-antisub/602-questions-mount-over-hmas-canberra-and-adelaide-problems
Two brand new Helecopter troop carrier ships have been stuck in Sydney for several months whilst they figure out what the problem is.
These vessels use a similar Gas Turbine and Diesel gensets , but in this case powering dual Seimens electric thrusters.
The issue appears to be with the Seimens Azipod thrusters (2 x 11 MW) rather than the generator systems

 

[Hillhater]

Dang, you guys are making me want to drive down to San Pedro and find out if there's any tours of the big ships and their drive systems. I've been on the Queen Mary tour, it didn't used to go in the engines. They might not be there anymore.

I went on the QM tour also in Long Beach in the early '80s (stayed onboard in the hotel) i recall the engine rooms had massive gearbox units with the covers off to let you see the scale of the kit.
Impressive engineering, ....but crap hotel !

I doubt any currently operational ships will allow public access to the engine rooms these days, thanks to the security risks.
Remember when you could go sit in the cockpit with the pilot on a transatlantic flight ?