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published on 15 December 2007 in energy

The city of the future

Urban area evolution  in the past two hundred years has followed a constant course, characterized by an exponential increase of the number of urban population in the whole world: in the 1800  only 2% lived in the cities, today by the end of the decade we estimate that half of the world’s inhabitants will live in large urban centers.
Experts share a common view that foresees the progressive growth of  large urban centers into megalopolis with millions of inhabitants : just in the past 50 years, 20 cities have expanded to over 10 million inhabitants, while the number of cities with more than one million inhabitants has quadrupled.
Naturally these facts have caused a long series of consequences, that influence everyday life in these urban areas as well as the ecosystems surrounding them.
Cities, in addition to affecting the lifestyle of their inhabitants, are responsible for many phenomena that influence the global climatic change.
At the same time research for technological solutions to new environmental problems has grown progressively: technology, as we’ll see, seems to be able to respond to urbanization emergencies in different and creative ways, by suggesting new mobility paradigms and resource exploitation, innovative discoveries in materials and techniques, sustainable solutions to urban planning.
The problem definition
International Institutions have always been interested in the urbanization process, but there is a complex story  behind this.
In 1978 Onu  created UNCHS (United Nations Centre for Human Settlements), proposing this agency as a centre for activity coordination aimed at the urbanization process.
Through support of technologies and resources, with the creation of local authorities and the supply of consulting services and technical assistance, the UNCHS has promoted the concept of sustainable urban development, focusing on  planning  processes and environmental management, on the development of eco-compatible infrastructures and on the preservation of social justice.
Facing the problems that followed the demographic explosion and the urban spreading during the latter part of the past century, the representatives of the General Assembly of the United Nations met in Istanbul, in 1996, to participate to the Second Global Conference on Human Settlements, or Habitat II: 171 Governments from around the world accepted the Habitat agenda and subscribed to the Istanbul Declaration, to promote sustainable human settlements.
So, at least from an institutional point of view, the international community has prepared itself for the beginning of a new global challenge, foreseen in what has been defined as “The Urbanization Millennium”.

The European scenario
In 1994, in occasion of the international conference on sustainable Cities in Alboorg, the European Commission has drawn up the charter of the European Cities for a sustainable urban model, subscribed by state representatives, local governments and scientific and entrepreneurial associations throughout Europe.
Together with specific aims to reach, the Sustainable European Cities Campaign was implemented, supported by single action plans and concrete interventions, able to involve local communities in environmental sustainability programs.
The VI action plan of the European Community for the environment, which was created in the year 2001 and subtitled “Environment 2001: our future, our choice” moves in the same direction.
The program focuses on four main themes closely related to urban area expansion: the impact of human activities on climatic changes and the concentration of emission gasses which are responsible for the greenhouse effect, the preservation of nature and biodiversity, the sustainable management of natural resources and of urban waste materials, the preservation of human health with relation to problems caused by pollution.
Old issues, new solutions
Large modern day metropolises are the cause of numerous side effects that damage the environment: if this is true for the cities of the industrialized world, it isn’t very different for the urban areas in underdeveloped countries that are exposed to worrying environmental risks, with heavy consequences on the ecosystem and on human health.
The main protagonist is pollution in it’s different forms, the one that affects water and air , soil and acoustic pollution.
Bad air quality poses a direct risk to the health of human beings and it can have different causes, such as bad mobility and public transport planning, industrial and heavy road transport pollution, the habit of heating and cooling public and private buildings.
The effort to find the proper solutions to these problems runs on parallel tracks: on one hand, technological research indicates which way we should be going, through the creation of innovative materials, the development of plants for the sustainable exploitation of resources and the ability to minimize the impact of urban activity on the environment in general.
On the other hand however, only man himself can determine the effect of the results: changing some of those dangerous habits and adjusting current lifestyles which are unsustainable for our natural resources is imperative in order to start moving in the right direction in our quest for environmental preservation.
Only through the definition of new behavior codes and the promotion of new urban development concepts, applied the cities of the XXIst century, will it be possible to develop eco-compatible and livable urban centers.
As we will see, this is the direction in which we are beginning to take our first shy steps.

Learning from nature
One of the most interesting scientific applications of the past years in environmental technology is the one that exploits the chemical process of photo-catalysis that imitates a very commune process in nature: the chlorophyll photosynthesis. The titanium dioxide (TiO2) characteristics, a semiconductor, permits the absorption of a small part of the solar spectrum and converts it in thermal energy, neutralizing a few organic composts extremely dangerous for human’s health.
The application of this discovery is simple but extremely important: thanks to construction materials use (cements, plaster, mortar, and special plastering) and asphalt containing titanium dioxide, streets, exterior and interior surfaces of citizen’s constructions are able to contribute in an important way in the fight against urban pollution, mostly on one of the riskier aspects of the environmental degrade, the air quality.
In a few words nitrogen oxides and fine dusts that cause pollution through porous surfaces of materials and bound with nanoparticles of titan dioxide that are in it, whilst UV beams absorbance cause the nanoparticles photo-activation, till causing a thermal energy charge equivalent to 30,000°C.
So most of the imprisoned compounds from the particles are burnt down at environmental temperatures too, in an oxidation process that transforms them into acid products that are harmless for our health and easily removed from rains or from substances presented in materials.
Two important and particular aspects make this process potentially interesting: low costs and results.
According to recent Cnr analyses, in fact, a one square meter surface of “intelligent” material is able to purify 90% of cube meter of air in 45 seconds; the same surface in the end is able to knock down polluted materials presented in 200 cube meters of air.
This means, in synthesis, that a square kilometer of covered up photo-catalytic material is able to eliminate 32 tons of pollutants per year.
These results, extremely positive, are even more interesting considering the production costs of the photo-catalytic asphalt cement: according to Milan’s commune, for example, for a square meter of treated material it is necessary to spend one euro and a half more than traditional cement: it is evident that compared to damages created by air pollution this solution demonstrates to be economically advantageous.
For these reasons there is a high interest towards “intelligent” building materials by international institutions: in Europe, for instance, the PICADA project (Photo-catalytic Innovative Coverings Applications for De-pollution Assessment) explicated processes and chemical mechanisms involved in the process and studied the efficiencies, development and trading.

The problem of traffic
Traffic, one of the principal problems in big metropolitan areas, might become sooner or later one of the solutions for waste of energetic resources that characterizes the contemporary cities.
An English Society recently presented a very simple invention but innovative at the same time called Electro Kinetic Ramp which is a sort of dynamo that is able to exploit cars’ passage to generate electric energy.
The device is formed by a steel platform positioned on the street at the soil’s height, divided into 3 moving parts: the ramps lower down every time a car passes and transmits this movement to an accumulator, that converts kinetic energy into electric energy.
At every passage, according to the car’s weight, the system is able to generate from 5 to 50 Kw of energy, immediately available for public illumination, traffic lights and road signs, all for free.
So the ramp can be easily utilized instead of artificial bumps for slowing down cars, or near by traffic lights.
It seems to be a good idea: till today more than 200 English communal institutions requested for the Electro-Kinetic Road Ramp.
The hybrid future
In spite of the debate on vantages of the utilization of hydrogen engines which is still going on today, it is possible to support that it will be one of the mobility protagonist of our century.
In these last years, in particular, researchers’ interest is for the new concept of hydrogen utilization, employed in hybrid engines alimented by combustion cells and with a reserve battery.
The practical applications demonstrate the efficiency of this choice, especially for public transportation: a few big metropolis of the world such as San Francisco, Taiwan, Tokyo and others, in fact, have hundreds and hundreds of buses alimented by the new hybrid engines.
Buses work with hydrogen engines with high pressure constituted by a fuel cell, that is joined by electric storage of the secondary battery: the double alimentation makes the hydrogen combustion process possible, and at the same time it realizes an interesting principle for the development of the future engines.
The battery in fact is able to alternate undetectably to fuel cells in accordance with the motion exigency, allowing to recuperate and conserve the energy produced during the car’s abrupt.
This characteristic makes the new engines generation particularly useful in cities, mostly when applied on buses that citizens use: every stop, in a certain sense, represents a “pit stop”.

Sustainable mobility
The atmospheric pollution caused by traffic remains one of the principal problems for life’s quality and for the inhabitants health of the big urban areas.
If on one hand technology is the research of innovative solutions for the engine propulsion of private vehicles, it seems to scientists more important to concentrate themselves on a new concept of public mobility.
The correct management of the traffic flow, in fact, is the important part above all that are related to the atmospheric pollution and to the waste of limited energies: we will in the following part talk about a few hypothetic and realized solutions for a sustainable mobility.
Replanning the past
A mobility project which is quite interesting nowadays started more than 30 years ago: it is called PRT, or Personal Rapid Transit, an interesting response for vehicles use in big cities.
The PRT, in fact, has the same functionality of the individual transport system, but has extremely different characteristics.
It is possible to describe a system of small cableway 3 places to sit each that move along railroad tracks which are elevated 6 meters from earth.
Every cabin has a small computer where you must insert the destination you want to go to, which is possible to reach through an articulated system of railroad junctions that surround the city, in correspondence of big arterial streets that exists in every metropolis.
The PRT concept is simple, and it is possible to summarize in the individual trip offers on public means, a sort of taxi of the future but different for a few important properties.
First of all there aren’t timetables and there aren’t long waiting times: every PRT unutilized remains put in the different stations that are along the course.
Since the system is completely automatic every person that wants to can take a seat in a cabin, digitalize the destination and enjoy the panorama.
Besides, every single trip doesn’t have halfway stops, optimizing this way the course’s time duration and the costs of the system management.
The over-elevated route allows to use the space below in different ways: bicycle routes, sidewalks, green areas.
Costs too, although appearances, seem to be reduced: it has been calculated  that a PRT system more or less costs half or one third less in comparison to a new lighter railway system.
The idea as mentioned before isn’t new: thirty years ago Richard Nixon asked for the planning and realization of the first PRT system in Morgantown city, West Virginia
PRT remained a concrete reality: in fact today not only two American metropolis are experimenting this project and in other four there are mini-subways based on the original idea that are working, but also in four principal European capitals seems to have a similar future which means that we will sit in a cabin too one of these days.
The intelligent transport
A sustainable solution of the public mobility in an urban environment is represented by IMTS (Intelligent Multimode Transport System), which is the result of a future project that today has become real.
The IMTS is a multimode system of bus-shuttles all connected one to another thanks to strong magnets at the top and to the bottom of every cabin, that are used on normal urban streets and on specific routes. At the center of these routes, in fact, there are other magnets that have the double function to control the direction and manage the speed: braking, speed and stops are controlled by a central system that optimize the resources necessary for a correct vehicle functioning.
The IMTS is alimented by compressed natural gas engines, that minimize the impact of public means on the environment.
It has a great performance in an urban context: on one hand the IMTS doesn’t need railways so it can move everywhere; on the other there is a complete automatic system which makes the vehicle extremely safe under a safety aspect.
The course from a stop to another is always monitored by an innovative central system, that is able to make its way in traffic.
The average speed of 30 km/h is fine with people that move around the city and it can move without tracks which is advantageous in other situations.

Cities of tomorrow
City planning of the XXIst century
Cities in the past 50 years acquired new characteristics causing this way new needs of planning and development.
Big urban centers that grew following above all an industrial economy, progressively took place a citizen model based on tertiary activities and on services, with new needs and difficulties.
This is the reason why planners and urban planners must study right solutions for nowadays changes for the metropolis of the world: the challenge they must face is to follow the modern needs without renouncing to planning and sustainable solutions.
Cities of tomorrow
The results of the processes we spoke about, Europe in the past years demonstrated a certain interest for a new model of urban planning, that takes into consideration the new difficulties and the different instruments that can be used to solve problems.
The PLUME project is moving in this direction (Planning Urban Mobility and Environment), financed by the European Union.
The aim of this project, that gathers up researchers and scientists of every member, is to create a knowledge combination that is able to transfer from the scientific community to the local institutions the methodological and technical innovations of contemporary urbanity.
The problems that must be faced belong to independent fields but complimentary of our cities, such as the territory use and its relation with transport systems, the social inclusion problems and connections between economic increase and urbanity structures of the city, the use of alternative vehicles instead of private cars.
One of the reasons of originality of this approach, already unique for the topics discussed, is the importance attributed to the sharing process of the projects with resident communities.
The promoters are convinced about this program but the only way to have a real sustainable change for the cities of the future is the participation of contemporary urban society with politics of development.
The results obtained in these years seem to confirm the positivism of this behavior: today’s bet is to transform this conception, innovative and still experimental in a certain way, into a planning instrument shared on a huge scale.

Written by Filippo Tessari

With the sponsorship of the Italian Ministry of Education, Universities and Research
 
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