Eco-tegels

The Ecotile addresses the need to develop sustainable self-sustaining energy sources for the future. The concept targets busy public spaces (sidewalks, metro stations, airports, etc.) where thousands of people frequent everyday. The force applied on the walking area by the human body is immense, with the average human weighing approximately 65kg (50th percentile male-female combined average). This force applied on each day on each 20cm sq. surface area even a thousand times during the course of the day is normally wasted human energy.

The Ecotile uses this pressure constantly applied on surfaces to generate electricity that can be used to power street lights, traffic lights, building interior lighting, etc. The Ecotile uses the concept of piezo-electricity generation to achieve this.
Piezoelectricity (from: pressure electricity) is a property of certain classes of crystalline materials including natural crystals of Quartz, Rochelle Salt and Tourmaline plus manufactured ceramics such as Barium Titanate and Lead Zirconate Titanates (PZT).
When mechanical pressure is applied to one of these materials, the crystalline structure produces a voltage proportional to the pressure. Conversely, when an electric field is applied, the structure changes shape producing dimensional changes in the material.
The piezoelectric materials for the Ecotile use polycrystalline ceramics These are versatile with physical, chemical and piezoelectric characteristics able to be tailored to specific applications. The hard, dense ceramics can be manufactured in almost any given shape or size. They are chemically inert, and immune to moisture and other atmospheric conditions. 
The Ecotile pressurizes a piezo-electric material when walked on. This causes the release of current, which is small, but with repeated releases, stored in a battery over a period of time can produce enough power for purposes such as street lighting, etc.
The Ecotile surface can be tailored for specific spaces and can range from clay to non-abrasive plastics, depending on the need. The lower half of the tile is tapered so that it concentrates pressure on the piezo-electric material and also makes the tile structurally stronger. The piezo-electric material is housed in a protective casing and is approximately 3 cm square in dimension, thick enough not crack under constant pressure.
The apparatus is attached to a base plate, which is rooted to the foundation of the road surface. The tile surface is supported by a set of four highly durable impact resistant springs, which ensure that the tile moves perpendicularly downwards no matter on which part of the surface the force is applied. The springs also ensure that the piezo-electric material is only pressurized when a person walks on it, hence the action being more “striking” than “pressing”, a process which generates a greater discharge. An internal voltage terminal and wiring system between the tiles carries the charge to the charging battery. 
The Ecotile can be laid in rows like a normal tile, with a reinforcing material in between the tiles, which protect the tile from water and dust, though all the internal components in the tile will have to be weather-resistant. The Ecotile does not hinder the normal walk cycle as the tile only recesses by 2mm when walked on.
In case an Ecotile needs maintenance, bolts on the top of the surface can be opened to provide access to the internal components without any masonry work required.
The Ecotile is only in a concept stage at the moment, and one can only specify the exact nature of the materials and working after a through development stage is undergone. Piezo-electric materials are expensive, but if mass-produced for such an application, may be economical in the long run. If successful however, it would be successful in using human energy otherwise wasted and would be a small step towards a more eco-friendly and self-sufficient human race.