Future Green Cities
Designing Future Cities: Alternative Energy

Teachers' Domain
December 22, 2008

Decades ago, city planners rarely considered alternative energy sources in their
designs. All cities and industries relied almost exclusively on fossil fuels for
their power. In this video segment adapted from ZOOM, students take on the role
of city planners and, with the help of professional engineers, work out design
solutions that incorporate innovative energy alternatives.

Because fossil fuel reserves are shrinking and their use is tied to global
environmental changes, most experts insist on the need for alternative renewable
energy sources, including some of the sources mentioned in this video segment.
Unfortunately, no perfect alternative has been identified. Each comes with its
own set of problems.

For example, although the sun offers an almost limitless supply of energy, solar
panels are expensive to produce, take up a lot of space, and convert only 15
percent of the energy they capture into usable electricity. They also produce
power only during cloudless days. Windmills capture another seemingly infinite
energy source. But they too produce electricity inconsistently. Other energy
alternatives, including nuclear fusion and hydrogen power, hold promise for the
future. At present, however, the energy cost of processing them or driving their
reactions are as high as the energy they produce.

Today, engineers are working both to improve existing technologies and to
develop new technologies in an effort to overcome the shortcomings associated
with energy alternatives. They are working to develop solar panels that are less
expensive to manufacture and more efficient at converting sunlight into
electricity. Some engineers and scientists suggest that launching solar
satellites into space, where they can collect sunlight 24 hours a day and beam
this energy back to Earth, may be the answer. Others are mapping the world's
windiest locations in order to maximize the return from future wind farms.

Even with so many alternative energy sources on the horizon, many experts insist
that we may be fast approaching an energy crisis. Some predict that accessible
fossil fuels will be depleted in as few as 40 years, unless the world moves
quickly to reduce energy consumption. By reducing consumption we can both extend
the life of the non-renewable energy sources we have now, and make the use of
renewable alternatives more feasible.

What sources of energy will power Mutombo? Are these choices appropriate for
the environment that the city is in? Which of these energy sources are

What is solar power? What needs to happen to energy from the sun before it can
be used by the citizens of Mutombo to run electrical appliances, turn on light
bulbs, or power television sets?

Choose one source of energy for Mutombo and explain what happens to it between
its collection and its use by the citizens of Mutombo.

What makes an energy source renewable? What types of renewable energy sources do
you have near your home?

Which of the steps in the engineering design process do the students use? Which
do they leave out?


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