The very factors that make cities weigh so heavily on the ecosphere – the concentration of population and consumption _ also give cities enormous economic and technical leverage in the quest for global sustainability.
Local governments and urban planners need to consider the tremendous benefits that densely populated areas can bring. A shift away from suburban sprawl, and toward concepts such as Smart Growth and New Urbanism, is the type of urban planning that is needed to take advantage of all the sustainability benefits a city can provide. The advantageous economies of scale and agglomeration of urban settlements result in:
- lower costs per capita of providing piped treated water, sewer systems, waste collection and most other forms of infrastructure and public amenities;
- a greater range of options for material re-use, recycling, re-manufacturing and a concentration of the specialized skills and enterprises needed to make these things happen;
- high population densities which reduce the per capita demand for occupied land;
- greater possibilities for electricity co-generation, and the use of waste process heat from industry or power plants, to reduce the per capita use of fossil fuel for space-heating;
- numerous opportunities to implement the principles of low through-put ‘industrial ecology’ (i.e., the creation of closed-circuit industrial parks in which the waste energy or materials of some firms are the essential feed-stocks for others);
- great potential for reducing fossil fuel use and other energy consumption of motor vehicles in favour of walking, cycling and public transit.