I was really sloppy about overbuilding and running too much energy over too big an area, so take my advice at little value and improve upon it.
Just be meticulous and use different save slots.
Time: 15 sec Grab the white gem with the help of a single shield, back away as soon as possible and start digging in for the tech and more energy.
Time: 1 min 3 sec (Sorry, didn't save for a while.)
I took a fire rate upgrade with my technytes, although in retrospect range might have made it easier to move my gun around. Anyway, it allows for your gun to protect your shields. Build energy as usual. Start building a dark beam for use later.
Time: 1 min 52 sec
Put up a beacon asap and grab the green gem on the left.
Time: 2 min 18 sec
The biggest help I can give you is to disable your dark beam as soon as construction is complete, otherwise once you grab the green gem you'll just start feeding it ammo nonstop. At this point that energy is better used to get your energy production above 12.
Time: 2 min 48 sec
Due to my horrible timing I made it by the skin of my teeth. I started firing the beam at 10.7x energy and used the built up ammo to push a few more reactors up and get to 12.7. But I made it... Just watch out for drones heading for your mirrors. Or not. There's probably not enough creeper in those wells to push over to your reactors.