Welcome!

You must choose "Call me the cleaner" option when getting this mission from the governor. -Thanks Protonaut

First off this is a method I worked out myself, which means it was probably not a very good (or fast) way, but it still worked for me.

Secondly, this video was recorded on the Bloodbath difficulty. Depending on your difficulty, it may be different (enemies.)

And lastly, if you did or didn't like the guide, or you know a better way to do this, let me know!

Thank you!

How Hard Can It Be?
Find the Power Crystal in the Power Station without setting off any alarms

The text in the next section could be used alongside or instead of the video, whichever you prefer.

The video starts just outside the Power Station, just after you are given the quest to destroy the crystal there. Go straight ahead until you get to the lift.

When you drop down from lift, head to the right and then left. Enter the first doorway on the right and hit the switch in that room to open up the warehouse.

Exit the switch room and enter the newly opened doorway just next door. Head down the stairs and find Macil's informer. (You can find him on the map)

Just choose the top option for everything when you talk to him to get your I.D. Leave the warehouse from where you came in, and head to the right, then go outside via the first doorway on your left.

Going left from the doorway, you should see a cave opening in the rock face. Enter it. Press the switch in the next area and go through to the connecting room. If there is a Stalker (spider-like machine) on the ceiling, it is possible to walk around it, otherwise it will drop down and try to attack you. If it does, use the knife so as not to alert everyone.

Head down the stairs in that room and kill the guy facing a wall to get a key. (Use knife or poison bolts.) Back up the stairs, walk the opposite direction toward room with a few pillars. Jump over the balcony into the water, then jump up near where the person is standing and press the switch next to him. (Ignore any robots that try to attack you)

After hitting the switch, drop down into the main room, then exit by pressing the switch inside the room with a small door, which opens the big door next to it. After heading out, return to the cave outside by going the same way as earlier.

Then go to the same area you jumped from, except this time, open a door on the right side wall. (The 3rd panel along from entrance)
Enter that doorway and follow the vent through to the end. There's an unavoidable machine you'll have to knife on your way. (At least on Bloodbath)

In the resulting room, use a radiation suit, enter the circle in the center of the room and go up the lift at the back. Talk to the man there, (choose the top options again), and press the 2 switches next to him.

Leave that room via it's normal entrance and turn right. A platform that you can walk along should come up at this point. Go along it and up the lift at the end. At the top, simply talk the guy there and the achievement should pop.