The only source for harvesting electric energy by Innowattech solution is this part of mechanical energy related to the asphalt vertical deformation, which is a percentage from the total energy of the vehicle (energy of the fuel combustion).
It is known that the vertical load of the vehicle's wheels yields compression stress, diminishing with depth. Innowattech's generators are embedded at a depth of about 5 cm; the area where the compression stressis maximal.
The external load results in the deformation in both the asphalt layer covering the generators and the generators, similar to the typical deformation in a piezoelectric column loaded under axial load.
The deformation of the generator and the shortening of the piezoelectric columns embedded in the generators, generate charges on the piezoelectric columns that are the source for the electric energy.
The energy needed to deform the road is a function of various parameters such as: the surface quality of the road, asphalt type, environment temperature and others.
Moreover, the stiffness of the piezoelectric generators is function of the piezoelectric material; thus, the weighted Young modulus of the generator is higher than that of the asphalt. When piezoelectric generators are embedded under the asphalt, the total vertical deflection of the road is decreased due to the higher Young’s modulus of the generator. It does not change the MPG of the vehicle.