As the use of solar power gets set to increase in the region, Jelle Post and Giorgos Mixoudis outline possible future technology options and considerations for MEP professionals.
The sun is the most influential energy source for our planet. Therefore the sustainable development of future buildings can only be achieved when the sun and the solar energy it produces is considered as such by all the stakeholders involved over a building's lifetime.
Solar energy in the form of heat is a big concern for building design engineers.
On earth, the sun provides eight thousand times more energy annually than humans consume over this period of time. Although a substantial portion of that energy can and should be exploited, an even larger part can have negative implications for development.
The Middle East's climate is a clear example of the sun's contradictive influences: the potential of renewable energy systems is huge, but the sun also substantially affects the daily lives of the region's inhabitants.
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The construction industry in general is also vastly influenced by the sun's extreme power. The operation and maintenance of buildings in the Middle East, for example, consume a vast portion of natural resources and energy - far larger than in other regions around the globe - due to the extreme climate conditions. While efforts must be made to exploit the sun for the supply of energy to buildings, ways to minimise demand by reducing the sun's influence must also be considered.
Harvesting the sun
Solar energy is found in various forms: light, heat, wind, wave energy, biomass and hydro-electricity all are alternative forms of solar energy. Various techniques to exploit this energy have been developed throughout the years. In building applications, the use of renewable energy systems is an active way of reducing fossil fuel consumption.
To date, technologies such as photovoltaic (PV) cells and solar flat plate thermal collectors have mainly been used as small-scale solutions, but other large-scale solutions are now available.
Parabolic trough power plants are the most successful and cost-effective concentrated solar power plant (CSP) systems currently available. These use a curved trough, which is tilted to continually follow the sun during the day, reflecting direct solar radiation onto a hollow tube running above the trough. A working fluid (thermal oil, water or molten salt) passes through the tube, being heated as it does so, this is then passed through a heat exchanger creating steam that drives a steam turbine.
A power tower is another example of a large-scale solar solution. This comprises a central collector consisting of an array of flat reflectors (heliostats) that concentrate light in a central receiver located on a tower. Molten salt flows through the receiver where it is heated to temperatures of up to 1000°C.
Storing and using solar energy
One advantage of using molten salt as a working fluid is that it enables energy storage. Energy storage of up to 12 hours is possible, enabling power supply for 24 hours per day.
Moreover, the heat that is gathered from solar collectors can also be used for powering absorption chillers and desiccant dehumidifiers in heating, ventilation and air conditioning (hvac) systems, or even for desalination systems.
Such installations can be coupled close to high-rise buildings or residential areas so that the production is carried out next to the place of consumption. These installations generally produce low noise levels and negligible by-products.
Coupling renewable energy systems with desalination and wastewater treatment installations is another concept that has excellent opportunities. Various techniques have been proposed and implemented in places with limited access to water but with high sun radiation, such as islands.
PVs, wind turbines coupled with reverse osmosis plants and distillation desalination systems coupled with solar thermal systems are among those concepts that have been successfully applied around the world.
Providing protection
Solar energy in the form of heat is a big concern for building design engineers. The external heat loads in the Middle East are vast, thus the energy needs for the cooling of building's can be double that needed in Europe.
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