Electricity at Jool

[JeSper]

I'm planning to lunch orbital research station to Jool but I'm not sure what is the best way to generate elecricity. Or maybe putting MPLs so far from the Kerbol is just a bad idea? I'd be glad to recive some tips :)

[GeneralVeers]

That far away from Kerbol, RTG's are probably the only thing that will be practical.

[Melfice]

Right.
There's a few options.

One is RTGs, like GeneralVeers said. You'll need a handsome few, I think.

Another option is to include so many solar panels. All the solar panels. All of them. No, more. Literally all of them. No, you're still thinking too small. I can't describe it better. ALL.

The final option is to download a mod (USI by RoverDude is a good option), and install a nuclear reactor on your station. That may be overkill if all you're running is an MPL. (There may be other/better options available as well. More efficient solar panels are, no doubt, available.)

[JeSper]

What about Fuel Cells (refuelled from a mining outpost)?

[JeSper]

Btw it seems like this mod is outdated.

[Melfice]

That is another option I completely forgot about.
Yes, if you're willing to set up a mining outpost on one of Jool's moons, or bring an asteroid in, you could mine for ore and refine it into fuel.

That could then be converted into electricity through the fuel cells.

EDIT: Is it? It's been a while since I've played. But mods for 1.3 /should/ run on 1.3.1 as well.

[Jupiter3927]

I would use gigantor solar panels with those huge batteries.
You never need more than a few thousand units of charge and the biggest solar panels give some electricity by Jool.

I had a probe using the ion engine with a few of those small sun tracking panels and battereis out by Jool and it worked for a while before it had to recharge.

[Overclock]

dude, i have so many solar panels on this station
http://steamcommunity.com/sharedfiles/filedetails/?id=1277165192
that there is enough electricity to run the ore converters even at jool

[andylaugel]

I've put several bases around Jool.

• For my labs, I'll have 8 RTGs. That generates 6 electricity/second, which is enough for my 5/sec labs, with a little left over to keep a probe core running.
  
• For my mining operations, I rely on fuel cell arrays to entirely power my ISRU, drills, and so forth. As long as you're on the ground, you don't have to worry about running out of power that way. If you are using too much power, shut down an unnecessary drill or ISRU until you're working withing your power budget.
  
• For my satellites, I typically just use solar panels and make sure there is a battery in the mix.

I have put satellites around Jool and its moons just using 2 XL panels, a battery, and a "Dawn" ion engine. No RTGs required. That said, I'll usually ease off the throttle around Jool so the battery isn't draining, or at least keep a close eye on battery charge. The big burn to slow into Jool orbit isn't that time sensitive, so you can take a little longer to do it.

[Overclock]

yes, i have ore converters on a station so that juuuuust in canse you forget an ore converter on your ship around jool, and this station is also around jool, you can get your ore converted into fuel. it has docking ports of ALL sizes, exept for a grabbing unit, because why would you need a grabbing unit on a station that can only orient itself via reaction wheels? note: it has over 50k elecrtic charge.

[Overclock]

i have 32 xl panels

[andylaugel]

Originally posted by jacob:

i have 32 xl panels

That should produce around 30.53 electricity/second, if ideally placed. (An XL around Kerbin produces 24.4 elec/sec, you'll only make x0.0391 that around Jool's average distance from the sun.) That's barely enough to run an ISRU, which requires 30 elec/sec. And if a panel gets blocked or isn't facing the sun 100%, you'll be short.

P.S.With 50k electric charge in batteries, you can run an ISRU 27 minutes 46 seconds. (50,000/30 = 1667 seconds).

[JeSper]

I think i ll go for fuel cells. How much fuel does it need? (how often will I need to do refuelling missions?

[Astronaut]

Originally posted by JeSper:

What about Fuel Cells (refuelled from a mining outpost)?

They will need fuel to run so it would be a waste of mass and funds. RTGs will save lots of mass, and if you have enough you can run the station normally.

[RoofCat]

you do mining and conversion on surface. Then you don't need all those heavy solar panels or anything. Fuel cells can sustain mining operations just fine.

You could also use RTG, but those are very expensive pieces of equipment. And you will need a lot of them. So many they will actually be heavier than fuel cells and cost like half a million for the same simple job.

Land your mining ship on Vall or Laythe (with airbreathing engines and "plane" in that case). Pol or Bop should be fine too.

[andylaugel]

We can use math to figure this out.

A lab requires 5 e/s. The most demanding probe core using 0.08 e/s (4.8 e/minute * 1 minute / 60 seconds). Lights, reaction wheels, and other systems can draw power too, so let's round this up to 6 e/s to power our station.

Batteries

Batteries are of course a short-term solution. But you can determine how long your base can function without power by dividing the charge stored on the base by your power consumption.

Solar

How well a solar panel functions depends on its distance from the sun--specifically the inverse square. When the distance to the sun doubles, the power output drops to a quarter of what it was before. Kerbin's semimajor axis--roughly the average distance from the sun--is 13,599,840,256 meters. The furthest Jool gets from the sun, it's apoapsis, is 72,212,238,387. Divide Kerbin's semimajor axis by Jool's Ap and square the result, and you get about 0.0355. Divide our power requirements by that, and see we'd need enough solar panels to generate 169.2 e/s around Kerbin. An XL solar panel generates 24.4 e/s around Kerbin, so...

We'd need 7 Gigantor XL Solar Arrays to power our craft around Jool--if we got them lined up just right.

An additional consideration is that a spacecraft in orbit around a world doesn't get sun 100% of the time.

RTGs

The PB-NUK Radioisotope Thermoelectric Generator (the RTG) generates 0.75 e/s. Divide the power required by the power generated, and we can see we'll need 8 RTGs.

This power is steady, but expensive. At 23,000 funds each, 8 RTGs runs 186,400 funds.

Fuel Cells

Note: The ratio of fuel used by both fuel cell parts is 9 units liquid to 11 units oxidizer--the same as that used by fuel tanks. Liquid fuel and oxidizer both weigh 5 kg/unit. Ore weighs 10 kg/unit. One metric ton = 1,000 kg.

A fuel cell uses 0.00375 units (0.1875 kg) of fuel per second to generate 1.8 e/s. We'll need 4 to fully power our lab running at 83.3%.
A fuel cell array uses 0.045 units (0.225 kg) of fuel per second to generate 18 e/s. We'll need just 1 to fully power our lab, running at 33.3%

So for every 1 ton of fuel...
Fuel cells will produce 9,600 electricity, or enough to power our lab for 26 minutes 40 seconds.
Fuel cell arrays will produce 80,000* electricity, or enough to power our lab for about 3 hours 42 minutes--clearly the better option.
(* Whoops. I got the wrong answer to that earlier. But it's still better than the individual fuel cells.)

We'll need to ship 0.075** kg of fuel per second to our orbital base--0.225 kg/second * 33.3% capacity.
(** Whoops again. Editted in the correct value.)

A more efficient operation would cut out the middle-man. If your lab is part of your mining base, we don't need to waste time, attention, and rocket fuel moving fuel or ore to your lab.

I lost myself in a math haze for a bit while writing this post, working out exactly how many drills a lab + mining operation would require assuming the biggest and best ISRU and drills were used. And did some testing to verify some of my numbers.

• You base will require 15x + 36 e/s, where 'x' is the # of drills operating. (1 30 e/s ISRU operation, 5 e/s for the lab, 1 e/s for "other")
  
• A 3-star engineer working in a place with 5% ore concentration will generate 0.6375x kg ore per second. (1.5 big drill * 100% once up to temperature * 85% engineer * 5% ore concentration * 10 kg ore/unit)
  
• A fuel cell array generates 80 electricity per kg of fuel.
  
• A big ISRU converts 1 kg ore into 1 kg fuel.
  
• Power needed (in e/s) == (kg ore mined per second) * (kg fuel created per kg of ore) * (electricity per kg of fuel)

Oddly enough, x = 1 in this case. You only need one 'Drill-O-Matic' Mining Excavator. And if you only have one drill, you'll need 3 fuel cell arrays (51 e/s needed / 18 e/s per array). If you add more drills, you'll need more fuel cell arrays.