Stadtwerke Duesseldorf AG. The Company's principal activity is to supply the city of Duesseldorf and its surrounding areas with electricity, natural gas, water and steam-generated district heat produced in a refuse incineration plant. The Company also operates the Rhine river port of Duesseldorf and the city's indoor and outdoor swimming pools. Electricity supply accounted for 48% of 2001 revenues; natural gas distribution, 25%; water supply, 10%; steam-generated district heat supply, 8%; waste incinerator, 7%; harbour operations, 1% and services and other, 1%.