With the release of 0.3.0 it seems Nether Star Generators are now a feasible power source.

Quick recap

A Nether Generator runs on Nether Stars. One Nether Star runs for 120 seconds, producing 40,960 RF/t, 819,200 RF/s, or 98,304,000 RF per Nether Star. If we use Steam Dynamos as a baseline, that means one Nether Star Generator is as powerful as 512 Dynamos, and one Nether Star is worth the same power as 48 stacks of coal.

There are two challenges for this power setup:

1. Handling the power gen.
2. Supplying nether stars

Power handling

Both TE and Mekanism are suitable for transferring and storing this power. With TE, the setup to store a full Nether Star of energy looks like this.

Note the TE conduits connecting to 5 sides of the generator (they're good for 10k RF/t per side, so to transfer the ~41k from the generator you need 5 faces), and the two Resonant Energy Cells (at 50M RF each, you need two for the ~98M RF from a single star), again connected via 5 faces each.

Mekanism is similar, although it's capable of transferring significantly more power per face. (The tooltips claim 12.8k RF/t for the Elite Universal Cables, but testing shows two faces is enough to transfer the full 41k, so that's clearly in error.) So...much less cabling needed, but given the cost of top tier Mekanism cables, it's not exactly a savings. An example setup is here.

You could also drop ~20 EIO Capacitor Banks next to the generator; they'll absorb the entire energy output. The cost is a bit absurd though, in my view.

Those setups will all store a single nether star worth of energy. It's trivial to automatically fill a Nether Star Generator (hoppers, item conduits, export buses, whatever), but trying to use 41k RF/t of power without wasting most of it is left as an exercise for the reader. :) As a first step, you can just keep a chest of nether stars near the generator, and drop one in whenever your power supply starts to get low.

Nether star creation

The obvious method is to set up an automated wither farm. This shouldn't be too hard with turtles, MFFS, heavily compressed cobblestone, etc. But as an easier alternative for many will be the recipe added by Xeno's Reliquary to duplicate Nether Stars. The consumables are:

• Diamonds (obtainable via Magic Crops, bees, automated mining, laser drills, etc.)
• Wither Skeleton skulls (obtainable via Magic Crops, bees, MFR auto-spawner, etc.)
• Glowstone (obtainable, again, via Magic Crops, bees, various mining setups, crafting from gold and redstone, witch farm, duplicated using Alkhahest using redstone, etc)
• Gunpowder (Magic Crops, bees, creeper farm, crafted from redstone and coal, etc.)
• Nether wart (Magic Crops, automated farm, etc.)

In short, some mixture of magic crop farms (which are now MFR compatible!), bees, and MFR auto-spawners should get you everything you need with a minimum of fuss. Just set up a few cyclic assemblers, and pipe the resulting nether stars into your generator.

And then giggle, because this is pretty ridiculous. I tested all this in a creative world, obviously; my next plan is to actually build it in a survival world.

(Note: An operating Nether Star Generator also will damage anything within about 10 blocks around severely. Not a major issue if you're running around with kitted out MPS, but otherwise you may want to design your cables and conduits carefully to keep your generator at a safe distance.)