Tesla Solar Roof Continued from here . As explained in my previous post, scientific research proves that cities are more sustainable for mankind to live - the characteristic compactness of cities, for example, lessens the pressure on ecological systems and enables resource consumption to be more efficient [ 1 ]. This assumes that cities will be built to sustain the population load they bear through appropriate infrastructure including public transport, sewerage / eco-efficient waste disposal, provision of parks or other recreational habitats etc. If one observes the ‘ecological cost’ of human living there are 4 direct costs: Food production and transport Waste & Sewage management and processing Human commute and communications Real estate needed for stay, recreation and occupational needs (incl. education and administration) Energy is a common cost underlying all four above costs in addition to other ecological costs they impose. Of course, these costs are dire