Environmental Engineering Reference
In-Depth Information
U N-H ABI TAT's
State of the World's Cities
report for 2006-2007 points out
that, in many cases, urban growth will become synonymous with slum
formation. Already, Asia is home to more than half of the world's slum
population (581 million) followed by sub-Saharan Africa (199 million) and
Latin America and the Caribbean (134 million) [3]. Cities and urban settle-
ments must be prepared to meet this challenge. To avoid being victims
of their own success, cities must search for ways in which to develop
sustainably.
A successful city must balance social, economic and environmental needs;
it has to respond to pressure from all sides. It should offer investors secu-
rity, infrastructure (including water and energy) and efficiency. It should
also put the needs of its citizens at the forefront of all its planning activities.
It must recognise its natural assets, its citizens and its environment and must
build on these to ensure the best possible returns.
Modern cities are products of fossil fuel technology—most of the world's
energy is used by cities themselves and by the farming, industrial produc-
tion and transport systems that supply them. Modern urban living crucially
depends on uninterrupted energy supplies. The world's major transport
systems start and end in cities. They are the nodes from which mobility
emanates, with low transport costs having rendered distances irrelevant,
plugging cities into an increasingly global hinterland [4].
As world populations grow (many faster than the average 2%), the need for
more and more energy is exacerbated as illustrated in Figure 1.1. The world's
electricity consumption in 2011 was 22 TWh/yr and estimated to reach
23 TWh by 2020 [5]. Such ever-increasing demand could place significant
strain on the current energy infrastructure and could potentially damage
45,000
40,000
35,000
30,000
25,000
20,000
15,000
10,000
5,000
0
Population,
million
Total produced
energy, Mtoe
Electricity
production/year
total, TWh
CO
2
emissions/year
total, Gt
1993
2011
2020
FIGURE 1.1
Key indicators for energy demand and CO
2
emissions. (From
World Energy Council, Energy for
Tomorrow's World, the Realities, the Real Options and the Agenda for Achievement
, WEC Commission
Report, WEC, New York, 1993; World Energy Council,
World Energy Resources: 2013 Survey,
WEC,
London, 2013.)
