Review of the application of energy harvesting in buildings

This review presents the state of the art of the application of energy harvesting in commercial and residential buildings. Electromagnetic (optical and radio frequency), kinetic, thermal and airflow-based energy sources are identified as potential energy sources within buildings and the available energy is measured in a range of buildings. Suitable energy harvesters are discussed and the available and the potential harvested energy calculated. Calculations based on these measurements, and the technical specifications of state-of-the-art harvesters, show that typical harvested powers are: (1) indoor solar cell (active area of 9 cm(2), volume of 2.88 cm(3)): similar to 300 mu W from a light intensity of 1000 lx; (2) thermoelectric harvester (volume of 1.4 cm(3)): 6 mW from a thermal gradient of 25 degrees C; (3) periodic kinetic energy harvester (volume of 0.15 cm(3)): 2 mu W from a vibration acceleration of 0.25 m s(-2) at 45 Hz; (4) electromagnetic wave harvester (13 cm antenna length and conversion efficiency of 0.7): 1 mu W with an RF source power of -25 dBm; and (5) airflow harvester (wind turbine blade of 6 cm diameter and generator efficiency of 0.41): 140 mW from an airflow of 8 m s(-1). These results highlight the high potential of energy harvesting technology in buildings and the relative attractions of various harvester technologies. The harvested power could either be used to replace batteries or to prolong the life of rechargeable batteries for low-power (similar to 1 mW) electronic devices.