Developing Sustainable Cities
If a city is an organism, we need to understand its metabolism, this entails keeping its growth pattern under control and urban monster at bay
Herbert Girardet
Urban growth is changing the condition of humanity and the face of the earth. Half the world’s people now live in cities, with most of the other half depending on them for their economic survival. Mega-cities of ten million or more people are the largest, most complex structures ever made. They are the central hubs of modern economies and their transport systems. Their resource use and waste discharge dominates the human presence on earth. Fossil fuel technology powers modern urbanisation, but in the coming years many cities will become vulnerable to the rising tides of climate change. Across the world, we need a revolution in ‘future-proofing’ our cities, progressively switching to renewable energy technology and mimicking natural zero-waste ecosystems.
To become sustainable, cities have to mimic nature’s circular metabolism
Modern cities are not only the largest structures ever created by humanity, but they also use the bulk of the world’s resources. On just 2 per cent of the world’s land surface, and with half its population, cities consume over 75 per cent of its resources. An urbanising, industrialising humanity has fundamentally changed the very way in which the web of life functions.
Until recently, life on Earth was characterised by the geographically scattered interaction of millions of living species, to which local human cultures were intimately connected. In the last few decades an unprecedented assembly of urban centres has come to dominate all life on earth for the supposed benefit of humanity. Today we need to find practical ways of creating comfortable lifestyles for city people whilst reducing their intake of natural resources and their huge output of wastes.
Understanding the urban metabolism
To create sustainable cities, planners need to develop a clear understanding of how natural systems work. Cities everywhere need to be redesigned to become compatible with the natural world. The rich, modern cities of today have an essentially linear metabolism, whereas nature’s own ecosystems have an essentially circular metabolism. Nature knows no waste, every output by an ecosystem contributes to the continuous renewal of the whole living environment of which it is a part: the web of life hangs together in a chain of mutual benefit. To become sustainable, cities have to mimic nature’s circular metabolism, using and re-using resources efficiently and eliminating waste discharges not compatible with natural systems.
Among other things this means reduced distances between resources supply and demand: to increase the efficiency of urban consumption patterns also requires us to reintroduce the concept of proximity – reducing the distances of where key resources originate. For instance, the bulk of the food consumed in our cities should be supplied from peri-urban regions rather than being trucked and flown in long-distance expending huge amounts of energy in transportation.
Cities are centres of production and consumption, as well as communication: information technologies have given cities a global reach as never before, and particularly in further extending the financial power of urban institutions. The daily money-go-round from Tokyo to London, Frankfurt and Milan, and on to New York and Los Angeles is the most striking example of this. The new communications economy is organised around global networks of capital, management, and information, whose access to technological know-how is at the root of productivity and competitiveness. The challenge today is to exercise this power with a profound sense of responsibility appropriate to an urban age, and to use communication technologies to convey a clear understanding of how we need to do to make urban living compatible with the natural world.
From hydrocarbons to solar energy
Developing sustainable cities is one of humanity’s greatest challenges for the new millennium. A huge demand for energy defines modern cities more than any other factor. Vast agglomerations with tens of millions of inhabitants were impossible before the age of coal, oil, steel, industrial mass production and global trade. These vast horizontal and vertical urban structures depend on a continuous supply of energy – for operating their internal and external transportation systems, and for erecting steel, concrete and glass buildings that could not function without air conditioning, and without lifts ceaselessly going up and down.
Yet we need to realise that cities cannot exist in the long term relying on a continuous supply of fossil fuel energy: their supplies are limited and their combustion contributes to climate change, with rising sea levels threatening city people all over the world. There is no doubt that the sustainable cities of the future will need to be powered by wind and solar energy. Wind power is already cost competitive as turbine technology is refined further and further. Already 20 per cent of the electricity supply to cities such as Copenhagen is from wind power.
London, like most other large cities, at present is a fossil fuel junkie. It currently consumes around 20 million tonnes of oil equivalent every year and discharges about 60 million tonnes of CO2. But the new energy strategy of the Greater London Authority envisages a radical change – a combination of stringent energy efficiency measures, combined with the widespread use of wind and photovoltaic and fuel cell technology. This is expected to reduce London’s CO2 output by some 60 per cent by 2050. In 2006 London is starting construction of the world’s largest off-shore wind park in the Thames estuary which will supply 25 per cent of the electricity demand of London’s 7.5 million people!
Solar electricity is still much more expensive than conventional electricity, but its cost is expected to come down rapidly in the next few years. Large-scale government support programmes in Japan, Europe and America now give households and companies substantial financial incentives to install PV cells on the roofs and walls of buildings. In several European countries legislation allows the owners of solar roofs to charge up to four times the price for the electricity they sell to the grid as compared with conventional power stations. As a result, a global boom in solar energy is now underway. Housing estates, sports stadiums and public buildings in many cities are now being fitted with PV panels to make them largely self-sufficient in electricity.
Fuel cell technology is another important component of the future sustainable city, converting hydrogen straight into electricity without combustion, using an electro-chemical process. Fuel cell powered buses, trucks, cars and boats are expected to be mass produced within a few years. One important advantage they have for cities is that they don’t burn fuel when they are stationary in traffic jams or in front of traffic lights. Fuel cells can also be used to power buildings or whole urban districts. In various cities in Europe and America, fuel cell power stations are now coming on stream, making very efficient use of natural gas or methanol or pure hydrogen.
It is becoming clear that the dependence of our cities on fossil fuels can be dramatically reduced. Renewable energy technology is a key component in the ecological redesign of cities. Where practiced, it is already showing substantial economic and social benefits, including huge job and business potential. The creation of sustainable urban systems requires a combination of appropriate government and local authority policies and the active engagement of city people. Only determined effort will enable to us to ‘future-proof’ our cities.
