The Boeing 747-400, which is the latest model of the Boeing 747 range to date, has 5 fuel tanks. 2 in each wing and one in the cargo hold between the wings. The centre tank is the largest of them all. The basic model has a fuel capacity of 216,840 L and a maximum payload capacity of only 67,319 kg of passengers and/or cargo. It has a maximum take off weight of 396,890kg and a maximum landing weight of 285,760kg.
The Boeing 747-400 ER (Extra Range) can have up to 3 extra fuel tanks added to her. 2 tanks in the forward cargo hold and 1 in the vertical stabilizer. (The 2 little wings just under the tail). One tank in the forward cargo hold holds 228,990 L of fuel. In essence, a Boeing 747-400 ER can be virtually turned into a flying paraffin can. With all the extra tanks installed, it could fly around the world twice without landing.
The snags are that the more fuel it carries, the less pay load (Passengers, and/or cargo) it can carry. Fuel is weight and there is a maximum take off weight, as mentioned above, which can not be exceeded. If all the 3 additional fuel tanks the Boeing 747-400 ER were installed and filled up to capacity, she would exceed her maximum takeoff weight by at least 1 third without any payload.
To the best of my knowledge the only airline that has ordered the ER range is Quantas, who needed long range aircraft to fly between Melbourne and New York.
67 mths ago