The Co-operative Group has struck deals worth £25m to ensure all of its UK sites use energy from renewable sources.
More than 3,000 outlets, 16 regional co-operative societies and the Manchester HQ now use energy generated from wind farms or by hydropower supplied by Scottish Power and Scottish and Southern Energy.
The society is also implementing a programme to improve energy efficiency.
Martin Beaumont, chief executive of the Co-operative Group, said: “The Co-op has always taken its environmental responsibilities seriously and these contracts ensure we are managing energy resources as effectively as possible.”