quicksilver in my eyes

Although CFL (compact fluorescent light) bulbs are seemingly a fading technology, stores still carry them & people still buy them, so I still wonder about the mercury in them. Briefly, how much is in one and can get into the air/water/ground if the bulb gets trashed, versus how much mercury do we keep out of the biosphere if we don’t use the extra coal (with its traces of mercury) to power an equivalent incandescent bulb?
To set up an example, a 23 watt CFL bulb puts out about as much light as a 100 watt incandescent. Over the expected lifetime of the bulb (given as 9.1 years at 3 hours a day), it uses about 230 kilowatt hours, while the 100 watt uses a little over 996 kwh. Since about half the electricity in the U.S. comes from coal-fired plants, that leaves a difference of 383 kwh. How much coal does it take to burn that amount, and how much mercury goes up the stack?