overall system efficiency,factors, formula?

[mobile_bob]

had a phone conversation with Henry today, and it got me to thinking

while we are concerned (or at times at least some of us are for a variety of reasons) my thinking is it is possible that one might get hung up on a component of a systems efficiency without considering its integration and affect on overall efficiency of the system.

so what i am wondering is what factors might one consider or include in the consideration or development of a "system" efficiency?

some i think one could include might be

1. the prime movers efficiency, particularly where it will be spending the majority of its time running.
2. the generator/alternator head efficiency
3. heat recovery from cooling and/or exhaust exchangers, that is if it is harvested and put to beneficial use.
4. drive systems,
5. accessory drive systems, like pumps, fans, etc.
6. ?

then i wonder if as part of an equation might we also consider

1. ease of use/or implementation
2. first cost in dollars
3. ongoing maintenance costs, maybe per kw/hour? or per kbtu?
4. live with factor?  such as noise, db levels
5. cool factor, (most folks like things that are cool to look at or be around)
6. ease of modification, or adaptation for unplanned for down the road use
7. availability of repair/replacement parts, and consumables
8. ?

my thinking is that some of the listed factors have much more weight in the consideration than others, however
not many would want a unit that is noisy, expensive to maintain, a bitch to work on, and ugly even if it were able to produce 10% more power than maybe something more agreeable for each gallon of fuel burned.

that extra pint of fuel burned per hour adds up for sure, but maybe that extra expense is worth it if you have a unit that is in the end easier to maintain, cheaper/more available  parts, less noisy or any number of other factors.

i figure my time is worth something, and maybe i would be willing to settle for a bit more fuel burned if it were more agreeable all around?

does that make sense?

if so what do you guys think?  how would you weight these and other listed items, so that maybe a formula could be constructed so as that one could use it to maybe do an evaluation of a proposed system before he buys a bunch of iron, copper, nuts and bolts and heads out to the shop.

it seems like something like this might be useful, if not in absolute detail, surely in that it would make one go through the thought processes more completely before he moves forward with a project.

lets face it, at least here in the state, we aren't going to be getting any chinese/indian or even first world small diesel engine, in quantity, and at a cost most of us would be willing to pay.... and for those that might consider paying 3-4 grand for a water cooled tier 4 compliant small diesel, maybe what i am talking about would be very useful for that guy. that is before he drops the cash?

just kicking around some thoughts, getting late here so maybe it makes sense? maybe not? 

thoughts?