The 1976 Electricity Supply Act provided the framework for the control of the electricity sector, where only licensed companies were allowed to produce, transmit and distribute electricity through the public grids. The Minister of Energy was authorised to use security of supply justifications to oblige electricity supply companies to include specific energy types in their supply mix and to take measures to improve the energy efficiency of supply. Major changes to the Act in 1989 introduced the obligations for power suppliers to purchase power from renewables generation and CHP. Power from wind turbines was excluded as it was already regulated in detail through the Act on Utilisation of Renewable Energy Sources. In 1994, environmentally sound development of electricity supply was included as the main objective of the Act. The Minister was able to impose obligations on utilities to take measures pertaining to fuel use, energy efficiency and renewable energy development. In 1996, the EU directive to liberalise the electricity market was adopted and Denmark modified its legislation accordingly.