Description: IC² and Buildcraft integrate into each other neatly, especially with PowerCrystals addons, but it would be even better if not only items could be fed into machines, but liquids as well.
The thing I'm talking about mostly here are the Geothermal Generators. It would be superb if we could just connect it to a liquid pipe from BC and keep it running instead of constantly bucked feeding them.
If Balance is your concern here (this would be a lot of energy really easy to get) include some kind of hindrance to that. Either a "continous flow module" that needs to be attached to the GTG, that needs tons of precious resources (diamonds, glowstone dust, advanced alloy, ...) alternatively a second group of GTG could be made and have a destinction between "Batch GTG" (The classic one we already have) and "Continuous GTG" (The one for BC-Pipe-connectivity, would be way more expensive).
If that's not good, you could instead add a temperature problem similar to the Nuclear Reactor.
Another option would be the need of a simultaneous water feed - either as coolant or to make steam that propells turbines (thats how GTGs work in real life...).
No matter what variant you choose, I'd be very glad to see something like this come true in the future of IC²
The recipe for the continuous flow ADDON to a normal GTG could look like this:
(Where = Pump)
The recipe for the alternate continuous GTG could look like this:
(Again = Pump)
Liebe Grüße aus Südhessen!