Co-operatively owned renewable energy projects in the UK have been praised for their potential to allow communities to take control and benefit directly from clean energy production. The model for energy co-ops has been developing for over twenty years, and some organisations in the sector are questioning where they can go next. This thesis assesses how far there is scope for energy co-ops to develop further, by benefitting communities more widely and doing more to tackle environmental issues. The thesis draws on case study research undertaken at three energy co-op sites, in addition to an online questionnaire sent to 24 energy co-operatives associated with the intermediary Energy4All. By assessing the activity and visions held in these co-operatives it draws out promising areas of innovation. It also highlights the complexity of these groups, and the challenges that they face in retaining engagement and navigating relationships with other public and private organisations. The thesis identifies several key areas where further consideration, or support from intermediary groups, would be helpful to maximise their potential.