Red mangroves, Rhizophora mangle, in coastal areas have proven to be resilient for many decades. Mangroves accumulate mud, peat and plant matter through aerial roots (Pneumatophores) consist of rigid and flexible roots oscillating in the water. The oscillation of the flexible root not only decreases erosion but also provide a source of renewable energy. These oscillations can essentially be harvested as electrical power from tidal currents of the shallow coastal water in the form of pollution free energy by converting the kinetic energy of the moving fluid into voltage. We present an elastically mounted rigid patch of circular cylinders as simplified flexible mangrove roots to understand the role of flexibility on the vortex-induced vibration phenomena for energy harvesting. We performed kinematics and PIV measurements inside a water channel for the cylinders limited to a transverse oscillation inside a water tunnel at constant velocities . We investigate the effect of Reynolds number, mass ratio, damping ratio, and natural frequency of the system on the range of the achievable voltage. Higher flexibility resulted in increasing the frequency of oscillations with a reduction in the reduced velocity. This bio-inspired design has potentials for future electricity generations, as tidal currents are more predictable than wind energy and solar power as well as environmentally friendly due to minimal alterations to ecosystems and marine life.