Centralized vs. Decentralized power

[Murdoc]

Ok, can someone explain to me the rationale behind what is said on page 339, that basically centralized power takes twice as much fuel as decentralized power does? Because in general, larger power plants are more efficient and thus require less fuel than smaller ones. This was reflected in MT ship design (I don't know about other versions), and I would expect it here too, but instead it seems to be saying that the little mini-power plants connected to individual components are twice as efficient as the ship's main power. Is there a reason for this? Is it an error?

 

[Shonner]

Electric trains are less energy efficient than diesel trains. That may have been the designer's train of thought while writing that up.

 

[Original_Carl]

Just riffing here but I would think that centralized power would be more efficient, but decentralized power would provide better disaster recovery.

 

[Shonner]

Transmitting electricity has some loss to it over distances. Cat-5 and wi-fi have limits for distances. So you need signal boosting (hubs/repeaters/whathaveyou). It would be nice to have a motor on each wheel of a car. But then it becomes over-engineered doing that and more costly to fix if a wheel goes. So people live with drive shafts.

Anyway, the ref can ignore the ** and *** on the chart if he wants to. The players will not care in the least.

 

[LordRhys]

Centralized Power loses energy over distance due to inefficiencies in power transmission lines.

And when you create power with Generators, Centralized Power Generators are running all of the time, even when power isn't needed at specific locations.

Ship Power is very closely tailored to the needs of the ship and doesn't need to travel a great distance. The primary reason to decentralize ship power is for damage control purposes, a decentralized system can be harder to disrupt.

 

[robject]

I think it's related to the MegaTraveller Dilemma -- does the power plant power all components, including weapons and defenses, or does it just power the drives?

 

[Reban]

Maybe I have the wrong impression but Decentralized power relies on lots of little Fusion Plus plants in each major component. These are far more efficient than Fusion Plants and only need to be refueled once a year or during maintenance.

So all that fuel isn't counted on the p339 tables.

Errrm okay I can convince myself, but 1) It seems over generous and 2) It not a very good explanation.

 

[robject]

That sounds a lot like the design issue that MegaTraveller came up with -- all those power-hungry weapons and defenses just don't get used 90% of the time, so why power them all of the time with a gigantic central powerplant. Those weapon emplacements could have their own capacitor banks and small power plants, ready for action.

 

[Original_Carl]

This is starting to sound like the design meetings we have at work when we need new features for our software.

Dev1 "Let's do this!"
Dev2 "No, it won't be fault tolerant."
Dev3 "But, if we arrange it this way..."
Dev4 "Then we'll sacrifice performance."

And so on. I like that the game has enough latitude to allow this kind of thing.

 

[whartung]

That sounds a lot like the design issue that MegaTraveller came up with -- all those power-hungry weapons and defenses just don't get used 90% of the time, so why power them all of the time with a gigantic central powerplant. Those weapon emplacements could have their own capacitor banks and small power plants, ready for action.

More moving parts to maintain. More reliability testing to perform. Some devices work great if well maintained, yet continually operating in contrast to devices that are rarely used and instead just sit. More components mean more spares and more maintenance.

Redundancy is a value all its own, but a larger motor should be more efficient than several smaller motors. Consider locomotives. These are built as large as they can be. Rather than sticking together a bunch of smaller locomotives, it's better to hook up fewer larger locomotives. I won't say there are no applications, but outside of vehicles chasing speed records, I don't know of any industrial applications where several smaller motors are used rather than fewer larger ones. Large cargo ships use one or two enormous motors to drive the ship rather than a bunch of smaller ones sharing the same shaft.

After the 747, when was the last airplane to get four engines? And how much are the modern two engine planes really using them for redundancy and reliability than out right necessity? C17? Airbus 380? Not saying they don't exist, but it seems more rare than not.

If anyone is on the sharp edge of the bang/buck equation of power plant size to value received, the transportation industry gets my vote. They seem to know what they're doing, and they seem to go big.

If the larger power plant has the resolution and capability to scale up and down to meet demand, then there's lots of reasons to go with the big plants over several smaller ones.

As for power loss, what TL did the room temperature superconductors become commonplace?

 

[Murdoc]

Yes, decentralization has military applications, that's the trade-off for inefficiency, and why military items/vehicles tend to cost more than commercial ones. Commercial interests of course want what they can get away with cheaply, as whartung said. But as it stands in the rules now, there is no reason to use centralized power, because it is both less useful militarily, and is less fuel-efficient; it's a non-option. Could be easily cleared up with an errata though.

 

[Zutroi]

After the 747, when was the last airplane to get four engines? And how much are the modern two engine planes really using them for redundancy and reliability than out right necessity? C17? Airbus 380? Not saying they don't exist, but it seems more rare than not.

The Airbus A340 boasted "4 engines 4 the long haul"... Boeing's 777 twin-engine outsold the Airbus by an order of magnitude, all due to the increased maintenance costs of having 2x as many (but smaller) engines. Airbus delivered fewer A340s in the last year it was offered than Boeing delivered in a month of 777 production...