Siward Zomer is the chairman of Energie Samen, the Dutch federation of citizen energy cooperatives, and a board member of REScoop.eu, the European federation of energy cooperatives. He has co-developed several cooperative wind farms and currently serves on the board of one local energy cooperative in Amsterdam. Siward is also a board member of NCR, the Dutch Council for Cooperatives, and of NVDE, the Dutch Association for Sustainable Energy.