"Shut Down" wastes electricity due to unlimited wait for confirmation

When I Shut Down my system (10.10 Maverick Meerkat, 32-bit i386), I often don't notice the Shut Down confirmation box until hours later.

I suggest a big, obvious 10 second countdown clock with an option button to Cancel, (plus the current "Shut Down" button to save a little more electricity for those less scatterbrained than I).

If the user clicks neither button, Shut Down would automatically begin when the countdown reached zero.