An electric utility that operates a nuclear asset located in a county on the coast of the Gulf of Mexico shall pay a nuclear safety fee for the year 2000 and the year 2001 to each taxing unit in which the nuclear asset is located, other than a school district, in an amount equal to the difference between the ad valorem taxes imposed by the taxing unit in 1999 and the amount of ad valorem taxes imposed by the unit in the year for which the fee is due, except that the amount of the fee may not exceed one-half the taxes imposed on the asset by the unit in 1999. The nuclear safety fee shall be considered a tax or fee under § 39.258(5).