Having used these before, I can say for certainty that you can power an advanced pump from a single thermal generator. The 128eu/t is just the packet size it can accept. You don't need to give it that much per tick and it won't use that much per tick. Two thermal generators and one advanced pump is enough power to pump lava fast enough to keep a full stack of thermal generators constantly full. The only potential downside to the advanced pump is needing pipe to work. However given how effectively it drains an area (leaving no flowing lava), the pipe is easy to retrieve and reuse. In short, advanced pumps are amazing. Don't bother placing a BC pump ever again. Just make an advanced pump out of it instead.