Denmark has a strong cooperative energy sector with experience in sustainable technologies like district heating, wind power, electricity supply, and biogasification. There are approximately 400 consumer-owned district heating cooperatives and 250 community-owned wind power cooperatives, as well as some community-owned hydro and solar projects and a biogasification plant. Two notable energy cooperatives are Middelgrunden, established in 1997 with 20 offshore wind turbines owned by 8,600 citizens, and Samsø, a renewable energy island since 1997 with 10 wind turbines and CO2-neutral ferries owned by its 3,806 citizens. Lessons from such projects show that outside expertise is needed to help small communities tackle big energy problems and political and legislative