The central thesis of Planet of the Humans is that various people and organisations in the United States claiming to promote 'green energy' are actually promoting biomass energy--largely a euphemism for cutting down and burning forests--a practice which is not carbon neutral nor renewable nor sustainable. The film reveals the destruction of environments first-hand, and also explores how wind power and solar power don't fare much better than fossil fuels in terms of impacts once all the inputs for construction and maintenance are considered and compared. In most cases, the additional demands for resources and construction simply invoke more environmental degradation and pollution. The film examines this push for more industry through key figures in the modern environmental movement that are funded by entities connected to fossil fuels, or have established profit motives, revealing how the environmental movement has been essentially co-opted into a de-facto lobbying arm of 'green' industries. The film also posits that regardless of energy systems, overpopulation is a central problem of industrial civilisation, and that this current way of life is unsustainable no matter how it is powered or 're-imagined' by technology.