Participants arrive with foghorns on trailers, bladeless chainsaws, and noise-makers of every description, with the sole intent of creating an unruly din.
In other solar news, the Westmill Solar Cooperative launched the world's largest community-owned solar project in the UK, a group of African teenagers developed a pee-powered energy generator and Tunisian company Saphon Energy unveiled a new bladeless, bird-friendly wind turbine.