The Energy Department is shredding 4.8 billion gasoline rationing coupons that were printed but never used in the Arab oil embargo a decade ago, a Government spokesman said today.

It cost millions of dollars to have the coupons printed and stored at the Pueblo Army Depot in Pueblo, Colo., where they are being destroyed and buried, officials estimated.

''We are in the process right now of shredding these gasoline rationing coupons,'' said James Marna, a spokesman for the Energy Department. ''They are unusuble. They were never even printed with serial numbers.''

The Federal Energy Administration, now defunct, ordered the coupons printed in 1974 and 1975 when oil supplies from the Middle East were cut off..