Can we power Laptop by using Piezo electric crystals which is embedded in a rubber sitting mat???

Question

My idea is power the labtop by using piezoelectric crystals which is embedded in a rubber mat. It is a handy mat which can be carried along with the Laptop. This mat is to placed above the seat where we are going to sit and work on the Laptop.While working with Laptop considerable amount of our body weight acts on the Piezoelectric crystal and so a mechanical stress is developed on the Piezoelectric crystal between weight and seat.According to the Piezoelectric effect this mechanical stress is converted to electrical energy and the got electrical energy is used to power Laptops. If all these satisfies,the following questions arises:

1. How can we shape the piezoelectric crystal since it is very difficult to shape and very costly?

2. The power required is very high and how can we achieve more power rather than using PE crystals or Conventional energy?

Could you please give me the solutions ?

Answer 1

Yes. It an be done!

do 'make' electricity when stressed, but not when

Piezo electric crystals generate an electric potential in response to applied mechanical stress, but not when static. That is, only when being acted upon. They also only develop a volt or two at a very small current.

Not only would you need a lot of them, but you'd have to be very heavy and move your butt a lot. You probably couldn't move your butt enough sitting down and be able to use a computer at the same time. Did I say you'd have to be heavy - really heavy?

Answer 2

From wikipedia on piezoelectricity, it looks like you'll only get about 1 to 2 watts, while a notebook computer requires 50 to 100 watt.  See below.

The law of conservation of energy does not allow you generate more energy that what you put in.  The normal human body is burning about 100 Watts.  During heavy excercise it should be much higher.  The energy conversion of this type of system should be very low, thus if you get anything working at all, assuming a 10% efficiency of the piezo electric system, then you will need the human to be burning 1000 Watt to allow you to power the computer.  Perhaps Michael Phelps who requires 12,000 calories a day can do this.

"A similar idea is being researched by DARPA in the United States in a project called Energy Harvesting, which includes an attempt to power battlefield equipment by piezoelectric generators embedded in soldiers' boots. However, these energy harvesting sources by association have an impact on the body. DARPA's effort to harness 1-2 watts from continuous shoe impact while walking were abandoned due to the impracticality and the discomfort from the additional energy expended by a person wearing the shoes. Other energy harvesting ideas include harvesting the energy from human movements in train stations or other public places[8][9]."