Adding to the growing number of utilities offering renewables power at a "green tariff," the Bremen municipal utility Stadtwerke Bremen is marketing "Ökostrom" (ecological power) to its customers from next month. Customers opting for Ökostrom will have to pay a surcharge on a fixed portion of their consumption. In return they will receive a fixed minimum amount of power from a renewables source. The income from the surcharge will be invested in renewables plant. Further details, such as the size of the surcharge, are not yet available.