Speed-skating at the 2010 Olympics was delayed several times as the ice managers tried to deal with the new, electric ice surface refinishing machines. It turned out that these new “green” machines left grooves and puddles in the ice. Finally, authorities had the good sense to import a propane-powered standard zamboni to use for the remainder of the speed-skating events. For more, see this (h/t Eva).
And keep in mind that depending on how the electricity is generated and stored, it isn’t all that clear that electric-powered zambonis are any greener than the traditional ones.