[cstross]

Not as easy as you seem to think.

Dams = concrete, concrete = a whole lotta cement and other energy inputs; concrete production is one of our big unsung CO2 emission sources right now.

Turbines and generators = refined metal, including copper (dynamo windings) and steel (turbine blades) -- again, lots of energy required.

Okay, we can back it off a level and go for water wheels in rivers -- a Roman to mediaeval technology -- driving the dynamos; but it's still not going to work without refined metals (energy intensive) and waterproof insulators, which means gutta-percha or rubber or refined organic polymers -- all of which mean long-haul shipping or again, energy-intensive chemical industry.

These obstacles aren't insuperable, as long as we don't get knocked back to dark ages/monasteries preserving books and knowledge but no actual lights-on/wheels-turning infrastructure. If we get knocked back that far in a post-carbon-extraction world, it'd be devilishly hard to build back up again.

[atemerev]

No, it is much easier than you'd think. Energy breeds energy. You start with a smaller energy source, use it to extract resources and make parts for the bigger energy generator, rinse, repeat.

Wind turbines and small hydroelectric dams are simple. Megaprojects are harder, but it is easy to start small and extend from here. It is easy to make electric energy, and with enough electricity, everything is possible.

[maxander]

Oil drilling is one of the most technologically advanced industries that exist, if not the most, and the existence of such technology is predicated (currently) upon the existence of globally-available cheap energy. Non-oil-based development would likely hit a ceiling where there just isn't enough energy to progress long before you could recreate such an elaborate system.

[atemerev]

We only burn oil for energy because it is dirt cheap (yes, thanks to the economy of scale). Electricity can be produced by many other ways if oil becomes too expensive for that.