I suppose your options are limited to how much you're willing to build. You could do the less exciting options of lots of solars or pumping the nether of lava to fuel geothermal generators, or use a kinetic generator along with a wind turbine (kinetic wind generator in 1.7.10) but that does require rotors to be replaced after a few days if running constantly. There's other options still if you get more creative, such as running a tree farm to produce wood which can be cooked into charcoal then that used in generators. You could even use crops to produce biochaff, then ferment it into biogas which could be burnt for power in the semifluid generator.
You're certainly not short of options, even more so in 1.9+ where the old water and windmills are back with rotors.