lets just say with GT enabled you need aluminum to build the windmills w gregtech, you get aluminum (the correct type- there are 2 types of AL) This stuff needs to be smelted in a industrial blast furnace. IF you can operate a blast furance you are far beyond the need for a windmill, or watermill for that matter.
Coke oven - for coal coke
blast furance (non industrial type) with Iron + coal coak for 1 steel
steel plates for the industrial blast furnace, iron for the machine that runs the ibf.
you should have a dedicated MFE (medium EU) to power the industrial blast furance.
Easist way is to get a tank and fill it with lava via pumps and a tesseract from the nether.
output the tank (large xyz-craft tank 12x12x12 works good - made of any solid non-pourious material.. glass and marble looks cool.) into a line of liquiducts or bc waterproof pipes. Attach geothermal generators (or the thermal generators which are the upgraded version of the geo's) to a line of ic2 wires (the glass-fiber works best just silver - diamond - silver with glass above and below the center row on crafting table) You will need a MV transformer to step the power comming out of the MFSU's that you should have your thermal generators flowing into. Your also going to want a LV transformer to step down the MV line to power the extractor that you need to use to get the rubber to make all the copper/gold wires to make the above machines.
The tin that your going to need to use for the water/wind mills dont need rubber on it to function.
But as you can see from this simple example at the point where you can smelt the correct form of AL, you will be beyond the need for either wind/water renewable eneregy as lava is better.
I do like some of the stuff that greg adds, but a couple months to get 5 people enough iridium for the upgraded version of nano armor. were playing on the hard mode ultimate pack atm and with 4 quarries feeding everything cept gems/metal into recyclers and making scrap to power we still only have about 200 UU matter, which is a drop int he bucket for whats needed. The guildy that is running the serrver loves making thigs harder for everyone else so hes a big fan of greg's bs. THank god we all made our power armor before he decided it was too easy and changed to to the gt hard mode.. i bitched and he switched it back.. but yeah i dislike greg making things harder by defalt for everyone else.