Heating a City

Lets suppose I've got *lots* of energy to spend, and I only want to
heat just *one* city.  I'd like to raise the ambient temperature 20
degrees above the surrounding area.  YOU ARE LIMITED TO CURRENT
TECHNOLOGY, but have a VERY VERY LARGE BUDGET.  What might be the best
way to do it?  And about-sort-of how much energy might this take?


Ideas:  Put large electric heaters on every lamp post.
Good:  Practical if your energy supply is large enough
Bad:  Hard to get a 20 degree rise

Ideas:  Heat the water in the canals
Good:  Heating the canals would probably produce a nice even warming
Bad:  Only works in Venice

Ideas:  Run hot water under every street and sidewalk
Good:  Nice even heating
Good:  No need for snow removal
Bad:  Needs lots of piping
Bad:  Might lose lots of heat down into the Earth