For anyone interested in a very simple setup for automating a large turbine, here's what I did this morning.
Note about the build - you can do it 100% with vanilla redstone and GT, I just use a couple of other mods to make it significantly more compact.
Quantum Tank (LPG) -> LV Electric Pump -> Small Wooden Fluid Pipe -> Shutter/Machine Controller Combo set to "Open if Work Enabled" -> LV Fluid Regulator (5L/t for Large Ultimet Turbine). You can use any fluid storage, just attach the pump to the bottom of the Fluid Pipe instead of the tank below. EIO tank could remove the need for the pump entirely, but then you'd need a larger feeder tank to pull from for capacity reasons. This would work well if you were automating multiple large turbines from a Railcraft tank.
Each side of the battery buffer has an Energy Detector, set to Storage (with Batteries) and Inverted Storage (with batteries). Red Alloy wire from ProjectRed leads down to comparators from the same mod. The Dim Redcrystal from Automagy (powered from below by a lever) provides a constant 13 power signal to the sides of the comparators, only allowing signals through if the batteries are more than 13/15 full or less than 2/15 full respectively. The signals passed on are sent to an RS Latch that feeds the wireless transmitter than opens/closes the shutter feeding the turbine.
Note the microblocks below the battery buffer - those are necessary to prevent the red alloy wire from reading the dim redcrystal.
Question to people who know more about GT than I do - does the turbine take extra damage from choking the input?
EDIT for bonus thought about the setup: You could totally use two input hatches (which I do anyway because I'm cheap) to automate both methane and LPG in the same turbines. Just have some redstone logic reading from Railcraft tanks (or Bedrockium drums, or whatever) to control which shutter to open. Since you'll use two fluid regulators, just set them based on the correct fluid.