Nanotech Spotlight
Through the lenses of time, it can be evidently seen how glass windows have become a key building material in modern construction design, especially in the urban areas where a high concentration of high rise structures is clearly visible. At the same time, it is important to make this increasing urbanization as green as possible that is environmentally benign. With an increase in building height, for example, Burj Khalifa, its power consumption rises not only because of the presence of more people but also because lifting water, operating elevators, lighting common spaces etc. require extra amounts of power. Therefore, developing a complementary source of power which is clean and otherwise wasted is a key research topic for a sustainable future.
The Integrated Nanotechnology Lab at King Abdullah University of Science and Technology (KAUST), led by Professor Muhammad Mustafa Hussain, has explored a novel idea to integrate micro to nanoscale thermoelectric materials with the window glasses to generate thermo electricity based on the temperature difference that exists between the hot outside and relatively cold inside. When a special class of materials called thermoelectric materials is subjected to a temperature gradient, flow of majority carriers inside the materials occurs from the hot to the cold side resulting in a net generation of current. When an electric load is applied to this circuit, useful energy can be generated in response to the temperature gradient applied. So far, the temperature gradient that exists between the warm outdoor environment heated by the sun, especially in hot climate zones, and the cooler indoor temperature of a building has not been used for thermoelectric power generation mainly due to the presence of a blocking interface, example glass window, between the two temperature environments.
Thermoelectric materials deposited on one side of the window will only be influenced by the temperature on that side of the window, while the temperature on the opposite side of the window will not influence the thermoelectric material. In other words, there is no temperature gradient being applied to the thermoelectric material, therefore no power will be generated.
“We have worked on the novel idea of transforming the glass windows into thermoelectric generators by depositing the thermoelectric materials through the glass rather than depositing it on either side”, notes Professor Hussain. “This way, the two temperature environments can influence the thermoelectric material simultaneously and the temperature gradient can be utilized for power generation.”
Successful prototype installation promises 304 watts of highly sustainable renewable power generation from a 9 square meters of thermoelectric window with a temperature gradient of 20O°C between indoor and outdoor environments of a building. When equipped with these power-harvesting windows embedded with nano-manufactured thermoelectric legs, modern high-rise buildings will have a complementary source of electricity that can run even when there is no sunshine, utilizing the presence of hot outside temperatures even during night times especially in hot climate regions with average temperatures exceeding 457°C.
The plans are to extend this idea by integrating thermoelectric materials through walls and doors of buildings to tap a maximum amount of heat available in the outdoor atmosphere.
Shikhar Singh, IIT Roorkee
