the past century, there has been an increasing trend towards urbanization. In the
year 1900, approximately 150 million people lived in urban areas with
populations of 20,000 or more. This amount was less than 10% of the world’s
population. Today, this population has grown to approximately 2.2 billion,
which constitutes close to 50% of the world’s population. High rates of
urbanization have resulted in drastic demographic, economic, land use, and
climate changes. The growth and expansion of our urban centers entail the
construction of new roads, buildings, and other various human made structures
to accommodate the growing population, and in turn, the destruction of the natural
ground cover and landscape, leading to global warming.
warming happens due to the increasing quantity of greenhouse gases in the earth
atmosphere produced by human activities, like the burning of fossil fuels,
mining and deforestation. Global warming causes many negative effects
especially towards the environment. Increasing temperatures around the world
are making glaciers and ice especially at the Earth’s poles to melt at a faster
pace than in the past. The effect of ice melting will leads to the raise on sea
levels because the melting glaciers become a part of the oceans. Besides that,
species such as polar bears will lose their habitats or extinct due to climate
change. Various birds will migrate to other place as they cannot adapt the
habitat that changes their living or temperature. Stronger hurricanes and
cyclones will occur as an effect of global warming leading to destruction and
damages of houses and buildings.
the global warming keeps worsen days by days, engineers have to be smart and
creative in designing their products. So, one of the heat transfer application
that is currently used in solar power management is solar power tower. It is
also known as ‘central tower’ power plants or ‘heliostat’ power plants. Solar power towers are one of the
most promising applications in the utilization of solar energy to produce
electric power on a large scale. It uses an array
of flat, movable mirrors called heliostats to focus the sun’s rays to a
receiver on top of the tower. The receiver will absorb the radiation and then
utilized it to produce electric power.
A heat transfer fluid which was heated in the receiver is
used to generate steam, which is used later in a conventional turbine-generator
to produce electricity. Early power towers’ design used these focused rays to
heat water, and used the resulting steam to power a turbine. Current designs uses molten salts (40% potassium
nitrate, 60% sodium
nitrate) as the working fluids are now
in operation. These working fluids have high heat capacity, which can used to store the energy before using
it to boil water to drive turbines. These designs also allow power to be
generated when the sun is not shining or during the night.
solar power is one of the main components of a
solar power plant. This tower is placed in the center of a large array of
mirrors. Sunlight is concentrated and directed from a large field of heliostats
(mirrors) to a receiver on a tall tower. Then molten salt from the cold salt
tank is pumped through the receiver where it is heated to 1050°F or 566°C.The
heated salt from the receiver is stored in the hot salt tank. Later the molten
salt is pumped from the hot salt tank through a steam generator that creates
steam, which drives a steam turbine, generating electricity. Lastly, the cold
salt at 525°F or 288°C flows back to the cold salt tank and is reused.
comparing solar power towers with others solar power technologies, solar power
towers are the type of electricity generation technology that is cleaner than those
solar power generating electricity by using fossil fuels.
Thus, solar power towers are one of the cleanest options for generating
electricity. Despite this, there are still associated environmental effects of these
towers. First, a survey and analysis shows that there are
still greenhouse gas emissions associated with
the fabrication and construction of the tower and mirrors, as well as
greenhouse gas emissions from dismantling and recycling once the plant
is done being used. However, these emissions are significantly lower than
emissions from fossil fuel combustion.
issue would be a very high water demand is needed as solar towers require large
volumes of water to operate. After some analysis, engineers decided that some alternative
cooling technologies are to be investigated such as the possibility of
using air cooling
to minimize the amount of water being used in the solar power tower.
The final potential impact of using the solar power towers
is the harmful effect towards the birds. The birds which fly in the way of the
focused rays of Sun can be incinerated. Some reports of bird deaths at power
plants such as these amounts the deaths to about one bird every two minutes.
During the operation of the solar power tower plant, no
hazardous gaseous or liquid emissions are released. Hence solar power plant is seen
as one viable solution for renewable, pollution-free energy. If a salt spill occurs, the salt will freeze before
significant contamination of the soil occurs. Salt is picked up with a shovel and
can be recycled. If the power tower is hybridized with a conventional fossil
plant, emissions will be released from the non-solar portion of the plant.