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The world has changed a great deal since the
Industrial Revolution. In just the past 50 years, humans have made
unparalleled strides in the theory and practical application of
science and technology. This becomes self evident as we look around
and see how science has changed our lives. We live in
climate-controlled houses, drive cars and fly in airplanes to reach
far away destinations, communicate by computer, enjoy refrigerated
beverages and foods, and have the ability to light up the night with
electricity. At no point in human history has humankind enjoyed so
many fruits of technology. It is often tempting to believe that this
modern world we have created is a better place in which to live
simply because it is a more convenient place in which to live.
However, the more we expand our horizons with modern technology the
more we become trapped by it. We are now dependent upon our lights,
cars, air conditioning and computers - and almost all of them are
powered by resources which are rapidly running out. The electricity
that runs almost everything we use is generated mainly by coal, oil,
natural gas or nuclear energy. Coal, oil, and natural gas are all
fossil fuels. Once burned, they can never be used again - and their
byproducts, such as carbon dioxide, carbon monoxide, oxides of
nitrogen and sulfur dioxide all contribute to degradation of the
atmosphere and environment. Nuclear energy presents its own set of
problems, not the least of which is the containment of its toxic
waste byproducts and the extremely long half-life of uranium.We are
burning fossil fuels at an unprecedented rate, despite our
realization the production of these fuels cannot continue
indefinitely.
Fortunately, there is. Scientists are working hard to develop large
scale applications for renewable energy sources, which is also be
used to make electricity, power cars and heat and cool our homes.
Renewable energy comes from resources which will never run out, such
as sunlight, water, wind, biomass and waste products. These forms of
energy are our best hope for a life and world which will be cleaner
and more efficient, and many are being used today.
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Solar energy is one the
most resourceful sources of energy . One of the reasons for
this is that the total energy we recieve each year from the
sun is around 35,000 times the total energy used by man.
However, about 1/3 of this energy is either absorbed by the
outer atmosphere or reflected back into space (a proccess
called albedo).Solar energy is presently being used on a
smaller scale in furnaces for homes and to heat up swimming
pools. On a larger scale use, solar energy could be used to
run cars, power plants ...
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Wind power is another alternative energy
source that could be used without producing by-products that are
harmful to nature. Like solar power, harnessing the wind is highly
dependent upon weather and location. The average wind velocity of
Earth is around 9 m/sec. And the power that could be produced when a
wind mill is facing the wind of 10 mi/hr. is around 50 watts.
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Hydroelectricity comes from
the damming of rivers and utilizing the potential energy stored in
the water. As the water stored behind a dam is released at high
pressure, its kinetic energy is transferred onto turbine blades and
used to generate electricity. This system has enormous costs up
front, but has relatively low maintenance costs and provides power
quite cheaply. Even the power of the tides can be
harnessed to produce electricity. Similar to the more
conventional hydroelectric dams, the tidal process utilizes the
natural motion of the tides to fill reservoirs, which are then
slowly discharged through electricity-producing turbines.
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Geothermal energy is the heat
from the center of the Earth and it is a clean and sustainable
energy. Resources of geothermal energy range from the shallow ground
to hot water and hot rock found a few miles beneath the Earth's
surface, and down even deeper to the extremely high temperatures of
molten rock called magma.Almost everywhere, the shallow ground or
upper 10 feet of the Earth's surface maintains a nearly constant
temperature between 50° and 60°F (10° and 16°C).Geothermal heat
pumps (GHP) can tap into this resource to heat and cool buildings. A
GHP system consists of a heat pump, an air delivery system (ductwork),
and a heat exchanger—a system of pipes buried in the shallow
ground near the building.In the winter, the heat pump removes heat
from the heat exchanger and pumps it into the indoor air delivery
system. In the summer, the process is reversed, and the heat pump
moves heat from the indoor air into the heat exchanger. The heat
removed from the indoor air during the summer can also be used to
heat water, providing a free source of hot water.
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