At least in the US, a modern incinerator produces cleaner exhaust gases than a power plant does. This is because the air quality restrictions are quite tight, and building an incinerator from the ground up with those restrictions in mind results in exhaust flues with filters to catalyze by products into non-aerosols.

That said, providing heat is the best use for this since even low grade heat (100 - 150 degrees C) is usable for heating buildings and water for washing etc. But you can't pull a lot of electricity out of it with steam turbines.