Power sources for Ships, nuclear, gas turbines, solar, etc .

[Nicknick]

A 40 MW peak power MT30 maintains ~40% efficiency from 25-35MW. I like hybrid battery electric power partly because it enables you to run a powerful engine like an MT30 intermittently at an efficient setting. A solid state 400wh/kg battery pack weighing 100t for 40MWh of storage could allow you to draw 5MW for 8 hours, and then run an MT30 at 25MW for two hours to take the load and recharge the pack. If you also have a small ~5MW generator (probably a diesel, they do make sense at that size), then you can cruise at 8MW propulsion 2MW systems cycling the turbine every ~10 hours like that. Or you can go faster when the turbine is on and run it longer than two hours per cycle.

That 100t battery pack weighs about as much as two of the three AG1960 turbine gensets on a Flight III Burke. Ships have three generator sets because they need two running at all times to avoid a loss of power, but sufficient battery power can replace that need. You can split the pack into two 50t 20MWh units and now you have redundant power from the batteries alone so you can get away with a single ~5MW genset plus generators on your main turbine engine(s).

So you would end up with a system that is heavier and much more expensive than a Diesel system....

If you are really using the full capacity of the batteries, they will only last for about 1000 to 2000 cycles, which would be reached very fast. The fire hazzard of these batteries would be very problemstic on a war ship. Using duch an hybrid system would only make sense, if it would enable some king of stealth mode, which is hard to do with the Bourke class.

BTW I don't by the almost constant 40% efficiency between 25 and 35 MW...

I propose using one 6311 Diesels with a mechanical coupling on each screw. The drive systrm should enable to decouple the engines and use them as generators only for the hotel load. The power to weight ratio would increase because no electric motors are needed and the efficiency for fast cruizing would be the highest of all varients. The high efficiency of the Diesel would be combined with the high efficiency of the mechsnical drive system. Only at dlow cruizing this system would vecome less efficient than a Diesel with electrical power transfer.

 

[Nicknick]

Any microreactor should install through something like a well deck. In an emergency it should be jettisoned out through the same hole. Access to diesel installation/refit should also be through the same portal, to simplify long term operations. Most diesel engine blocks can be maintained for the life of the ship, which is why they use such heavy and robust versions. But with the ability to mitigate failed engines then higher efficiency engines can be an option. Turbines do not need to be located as far down as diesels if they are not mechanically connected to transmissions and solely provide thermal and electrical power. The downside of locating turbines too far off the center of mass/gravity is that they have much stronger gyroscopic effects than diesels. The location of the microreactor obviously would not.

Any groscopic effect depends on a change of the angular position, a lateral position change causes no gyroscopic effect. As long as the hull doesn't bend like cranzy, you can place the turbines wereever you want, the gyroscopic moments will allways be the same.

 

[DJK]

You don't know what you are talking about. The Arleigh-Burke class already has two engine rooms for redundancy. There is no single point of failure. One prop shaft per engine room. One set of combining gears per engine room. Each engine room has generator providing redundancy.

View attachment 809731

Most warships have separated engine rooms, but there are still single points of failure per prop/shaft for a mechanical drive. Actually the motor and shaft its on, as well as parts of electrical system are still points of failure, but they avoid potential damage to that long shaft. Probably cant move engine rooms too much because of the stacks, but a bit more flexible for a new design.

 

[MadRat]

I propose using one 6311 Diesels with a mechanical coupling on each screw. The drive systrm should enable to decouple the engines and use them as generators only for the hotel load. The power to weight ratio would increase because no electric motors are needed and the efficiency for fast cruizing would be the highest of all varients. The high efficiency of the Diesel would be combined with the high efficiency of the mechsnical drive system. Only at dlow cruizing this system would vecome less efficient than a Diesel with electrical power transfer.

The reason steam was king long before diesel, which also existed, was the sluggish change of motor speeds under a diesel. It was simpler to change both direction and magnitude of output under steam engines. This is why turbines are tied to diesel use on U.S. warships. Electrical motors help soften the complexity of mating the two technologies. And battery storage in military aoplications is disimilar to consumer products; they may literally outlast the ship.

 

[Nicknick]

Early Diesel ship engines could run in two directions. For two stroke engines, the solutioj was simple, for four stroke engines the problem was solved by an axial movable camshaft (still used for newbuild engines for river barges into the 80 th). Starting was done with pressurized air which allowed starting in both directions and starting valves were needed anyway, because no powerfull starting engines did exist(btw, this method is still in use for very large engines). Fast load changes have never been a problem on Diesel engines.

There is a reason, why steam locomotives used low pressure boilers with a large volume of hot water. Unlike in modern water tube boilers, the amount of steam beeing produced would automatically increase steaply when the pressure drops slightly. This made the mashines very responsive, but unable to reach even a modest efficiency (typicall around 10 %)

Starting a steam turbine has never been problem, but changing the direction was more tricky. In fear of gearing problems, a small auxillary turbine was used for thar purpose.

If you are refering to lio batteries with an unrealistic energy desity and a lifetime longer than a ship, you should use youre knowledge to became the richest man in the world!

 

[CastleBravo]

I'm not sure that the fantail of a destroyer would be the required 16ft-20ft deep to have both the ASW gear and your microreactors. In most cases, anyways.

Not to mention weight and balance issues with all the weight of reactors and shielding as far aft as humanly possible.

It's not something that would fit on most current hulls. A new hull with a higher helo deck would probably be needed, but not as high up as DDG-1000. Each reactor vessel has shielding built in, so additional shielding may not be required if you have the ability to quickly jettison each reactor in an emergency. Being at the back of the ship, additional shielding could be added on just the bulkhead forward of the reactors rather than all the way around. The compartment directly above the reactors wouldn't have the additional emergency protection, nor would the aft 20ft of the helo deck, but everything else would

So you would end up with a system that is heavier and much more expensive than a Diesel system....

If you are really using the full capacity of the batteries, they will only last for about 1000 to 2000 cycles, which would be reached very fast. The fire hazzard of these batteries would be very problemstic on a war ship. Using duch an hybrid system would only make sense, if it would enable some king of stealth mode, which is hard to do with the Bourke class.

BTW I don't by the almost constant 40% efficiency between 25 and 35 MW...

I propose using one 6311 Diesels with a mechanical coupling on each screw. The drive systrm should enable to decouple the engines and use them as generators only for the hotel load. The power to weight ratio would increase because no electric motors are needed and the efficiency for fast cruizing would be the highest of all varients. The high efficiency of the Diesel would be combined with the high efficiency of the mechsnical drive system. Only at dlow cruizing this system would vecome less efficient than a Diesel with electrical power transfer.

Why would the batteries be heavier than a normal ship plant? Flight III Burke has 3x AG9160 that weigh ~50t each. Diesel gensets would be heavier.

https://www.rolls-royce.com/product.../naval/gas-turbines/ag9160-generator-set.aspx

Ships need two gensets running at all times to avoid the ship going dark if one trips offline for any reason, and you need a third as an offline spare. Batteries let you get rid of one or two of the generators you normally need (two online at all times with an offline backup) depending on if you main engines are able to supply power.

The consumer price of a replacement Tesla pack is around $200/kWh. That would put a 40 MWh pack at $8M assuming the navy can't get a better price than the heavily marked up retail auto parts business. That's a rounding error on the 10-20 year operating cost of a warship.

Hypothetical plant for future warship:

100t 40MWh battery
2x 4MW Diesel generators (diesel does make sense at this size)
2x MT30 Turbines connected to shafts through reduction gears with 20MW electric motor/generators built in

You can creep silently at 4 MW (2MW systems, 2MW to shafts) for ten hours without running any engines.

You can run on diesel electric at a continuous 6 MW speed and have bursts of additional power/propulsion from the batteries as needed without using the turbines.

You can fire one turbine at an efficient 25MW, use it to power the ship (2+ MW), both shafts (6-23 MW), and recharge the battery as needed (0-17 MW).

You can fire both turbines and generators for an 86 MW flank bell, more than a burke.

You can use all engines, generators, and batteries to put 120 MW war emergency power to the shafts for an hour to dodge a torpedo or something.

You have instant 40+ MW burst electrical power to run future sensors and weapons even with all engines shut down.