ELECTRIC

Seems like the the Smallest of mixers are Elecrical Powered and so are some of the largest ones at the Batch Plant Level are  Electric motor driven also. Most that fall in between are Gasoline or Diesel powered.

Small Electric Mixers

Quiet Operation: Ideal for residential or noise-sensitive areas, or Indoors.

Zero Emissions

Low Maintenance

Fewer Parts and no Fuel System.

Easy to Transport and Store. 

Disadvantages for smaller Portable models.

Plugged into an Extension Cord when in use. Wet Location by nature of the work: May Trip GFCI.

Less Powerful than Gasoline or Diesel: Generally suited for lighter workloads.