It's not enormous, it's just significant compared to our current production/use, but here's the good news: there's more than enough energy for that available off planet. There's absurd amounts of energy available everywhere around us.

Consider: it seems that we should be able to support a technological civilization of billions of people on renewable energy alone. That means literally on a fraction of the sunlight that Earth captures. Now, Sun isn't focusing on Earth, it's an omnidirectional emitter. Which means there's some 74 000 times more energy than Earth is receiving from the Sun available just in Earth's orbital band alone.

Fortunately, space-related energy problems seem like they'll be solving themselves, in lock step with increased space capabilities.