Energy consumption has emerged as a key issue for designing next generation wireless networks for an all-pervasive spread of a low-cost Internet of Things (IoT). Energy-constrained wireless networks have limited lifetime due to the difficulty in replacing or recharging batteries in the nodes. The required power for a single node is ranging from a few mW to several W and wireless networks are frequently located in remote areas difficult to access. Conventional wind turbines and fuel/solar cells work on totally different energy scales (from kW to MW). These strategies cannot thus contribute to the IoT revolution. Only a U-turn in the small-scale/low-cost/low-power energy harvesting (EH) technologies would allow the ultimate spread of IoT.
Harvesting energy from low-speed (a few m/s) wind/water currents by elastically-mounted flapping wings is one of the most attractive, low-cost and efficient strategies [Mc81,B012] to extract energy from the environment in the power range of several mW. In the power range of several W, networks of many harvesters must be assembled.
There are however at least two crucial weaknesses shared by all flapping wing harvesters causing severe limitations to the further growth of their efficiency:
i) turbulence, which is ubiquitous, must be filtered-out for the flapping to emerge;
ii) the wake effect is detrimental [Ol19], inhibiting in this way the construction of spatially-confined networks of harvesters to increase the power from mW to W.
The aim of the thesis is to turn these weaknesses into strengths: the feasibility and originality of this thesis rely on the innovative idea of combining turbulence ubiquity with a new low-cost extraction/storage strategy. The ambitious target is to extract at least 1000 times the electric power nowadays achievable by networks of conventional flapping wing harvesters. The field of small-scale energy harvesting can in this way keep-up with fast-changing developments of wireless communication technologies, thus allowing a revolution for an all-pervasive spread of a low-cost IoT.
[Mc81] W. McKinney and J. DeLaurier, J. Energy, 109 (1981)
[Bo12] C. Boragno, R. Festa and A. Mazzino, Appl. Phys. Lett., 253906 (2012)
[Ol19] S. Olivieri, C. Boragno, R. Verzicco and A. Mazzino, J. Fluid Struct. 90, 334 (2019)
To be carried out in collaboration with the Okinawa Institute of Science and Technology (Japan).