Or power the boiler using solid fuel. Charcoal is a bit of a setup to make, but a tree farm using some of the biomes-o-plenty trees, cherry blossom trees in particular, is self sustainable and can easily supply the boiler with the charcoal needed. You'll just need a planter and harvester(no fertilizer needed with cherry blossom trees, they grow that fast on their own, and produce vast amounts of wood, really) for the tree farm, and a pair of furnaces to convert the wood to charcoal.
Benefits:
1: lots of wood, over 40 blocks of wood from the bigger trees. And most of the trees should be of the larger variety.
2: nearly as many saplings as wood. Good for making biomass/biofuel as well.
3: renewable
4:a single farm growing as few as 11 cherry blossom trees can sustain a single, hot, 36HP boiler indefinitely.
Drawbacks:
1: infrastructure... needs several machines and a good power base to get the boiler up to temp before it becomes self sustainable.
2: Causes some block and/or frame lag when your near the tree farm. Best to have it chunk loaded at a distance from your main base.
3: Noisy...... :\
4: Can be messy.
BTW: 720mb/tick of steam relates to 13 blocks of enderium for the coils and 28 turbine blades. A turbine that size, running at about 1800RPM, should produce around 8214RF/tick. I do not have the numbers for Ludicrite(the pinkish alloy in big reactors) yet so do not know how many would be needed of those blocks, or their output from 720mb/tick. would need less blocks though, but the same number of turbine blades.
You slow down the RPM by reducing the flow of steam in the turbine. By default it would say 2000, dropping this down will let you stabilize the turbine at the speed you want.
other options include:
1: ender power, if you have a constant, and substantial, surplus of enderlily seeds and ender pearls. You'll need quite a few generators...
2: nether star power. If your willing to make a large wither factory with all the spawners and killing rooms that go with it.
3: More magmatic dynamos? Something like 10 more with a way to turn them on and off remotely as needed.
4: .......
:edit: ok, if you use 30 blades(odd numbers of blades act funny...), 13 enderium blocks, and 1 block of iron for the coils, you should be able to run the full 720mb/tick through the turbine and use it all. Otherwise, the 13 enderium blocks would only be using around 706mb/tick. This would be if your trying to keep the turbine as close to 1800RPM as possible.