Piezoelectric Smart Grass
In the future, there will also be
another system that will generate
electricity, which we have named
piezoelectric “Smart Grass”. This
will use piezoelectricity to harness
the power of the subway wind.

Fig 7. Wind blowing against Piezoelectric Grass causes piezoelectric crystals at bases of blades to flex, generating electric current.

Amazingly, 1 cubic cm of quartz, with 500 pounds of mechanical force correctly applied, can generate 12,500 volts. When a subway train passes it generates wind that blows on the wall of the tunnel. We will install what we call “Smart Grass” on the walls. This works when the wind pushes on small blades that protrude from the walls, like grass. When the “grass” flexes it pushes on a piezoelectric crystal converting the wasted wind into a usable electric current. The wind at the back of a train is very turbulent and its direction changes rapidly and randomly and the design will also help us tap into the very light wind current in the train tunnel, maximizing the efficiency.

Fig 8. Squeezing a piezoelectric crystal displaces the centers of positive and negative charges relative to each other, producing a current. This is the principle of the Piezoelectric Grass.