The usually, fossil fuels
are used to produce electricity, they are polluting and limited, however
renewable energies are not always as useful as it may appear. Fluctuating
renewables like Wind, Wave and Tide, Photovoltaics are supplying electricity
when the weather conditions allow, not necessarily matching the demand of a
civil-industrial society
Natural
sources that are capable of supplying electricity at any time and “ON DEMAND”
are big dams like the Aswan high-dam and geothermal sources, both are limited
to certain sites. Solar Thermal power stations are limited to two large bands
on the globe, called sun belts at the latitudes ca. 20 to 30 north and south.
In these large areas, the sunrays are generally direct, allowing a
concentration of the same by means of several mirrors and thus reaching a high
temperatures of over 500° centigrade. This temperature is sufficient to produce
steam from water and thus drive a steam turbine, and in addition store a part
of the heat in a special salt mixture placed in a sufficiently large insulated
tank to bridge the night. This allows a continuous operation 24/7 and on demand
Even
in the sunbelts there are some days of heavy clouds and also sand storms,
amounting to 3-5% of the year. For these few days, a burner is to be used to
heat the stored of the existing salts taking advantage of the presence of steam
turbine
and generator, thus allowing an interruption-free and weather-independent
operation at very limited costs
Such
solar thermal power stations are capable to replace fossil power stations
because they have the same performance, and moreover, they are capable of a
very effective seawater desalination if placed beside seashore. However, they
cost 6-8 times of an equivalent fossil power station
Following
method is suggested to overcome the financial burden and get favour of two
topics
Save
cost of fuel for the life time of the power station
Save
the expensive infrastructure needed to transfer the produced electricity from
large power stations to the customers
Till
now the old-fashioned thinking was dominating, which says that big units are
more cost effective; which is true, however, this policy leads to higher
infrastructure costs
The
suggested strategy consists of two steps
Planning
a gradual increase of building and deploying standardized units of 50 Mega
Watts each and place them as near as possible to the demand sites. Since the
sun shines everywhere in Egypt, then no need to look after fuel pipelines
and/or cooling water sources, as the standard design uses completely dry
air-cooled condensers for the steam turbine cycle
Keeping
the design unchanged, the condenser may be replaced by a desalination unit in
case the power station is near the sea; thus using the waste heat for
evaporation and condensing
Plan to install groups of five units – called Khemesa
connected together to form a local grid to supply the surrounding settlements
The
advantage of Khemesa is that it is completely self-contained, because during
winter, where the demand is about 20% less than in summer, one unit in turn can
be halted for periodic revision, and in summer all units will work and supply
excess electricity to the main grid. One gas turbine unit of 50 MW is added to
the to Khemesa local grid to secure its operation 365 days/year even in
emergency case
The
expected production cost reduction by increasing deployed standardized units is
much higher than expected by building bigger units (Economy of Scale). Moreover
small units of 50 MW are much faster to commission and enable the “Khemesa”
strategy. This in turn allows adequate adaptation to growing demand and saves
line connections and the involved losses
Mass
production of standardized 50 MW solar thermal power stations will open the
possibility to build excess capacity, which will be installed in the desert and
connected together to form an equivalent GW power station. The produced
electricity can then be sold to Europe to help EU’s efforts reducing CO2
emissions by closing the supply gaps of wind and PV. These supply gaps are
being closed now by coal fired power stations. Connecting the Egyptian grid to
the EU-grid brings seasonal advantages as the electricity demand in Europe is
seasonally opposite to that in Egypt
Each
installed and operated GW of solar thermal power stations in Khemesa strategy
will save 30-40 Billion US$ (depending on fuel costs) within the 40 years
service time a power station, accordingly, the initial cost of installation
amounting to a multiple (6-8 times) of the cost of fossil fired power station
does not matter much
The
expected financial savings for Egypt, assuming the current growth of
electricity demand is over 1000 Billion US$ within 33 years
NOKRASCHY ENGINEERING GmbH
The visual debate in Arabic Language
https://www.youtube.com/watch?v=dj1kA_rLtSA
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