Piezoelectric Energy Harvesting Turns Traffic into Green Energy

California has funded an experiment whereby roads which experience heavy traffic will be fitted with piezoelectric transducers to convert the vibration generated by vehicles (both stationary and in motion), into electricity. This electricity can then be fed into the grid to provide power for everything including buildings, homes, and street lights.
 

 Image courtesy of the Japan Railways Group.


Piezoelectric energy harvesting is not “new” technology. It's actually been around for some time. In fact, energy harvesting from foot traffic has not only been proven but is in use in some places. For example, several train stations in Tokyo use piezoelectric energy to generate the power needed to run the ticket machines and electronic displays. Another example is a Dutch nightclub which uses piezoelectric tiles on the floor to power lights.
To get an idea how much energy can be harvested, there is a transducer for sale that is specifically designed for generating electricity in energy harvesters. Here are some of the specs given:

• Open circuit voltage at rated deflection = 20.9V
• Closed circuit current at rated deflection = 57 microamps
• Power output at rated deflection = 7.1mW
• Operating temperature = -20°C to 90°C
• Dimension = 70mm x 31.8mm (height 1.5mm)
• 1 piece = $301  :  100 pieces = $132

Given this data, we can roughly project that the amount of energy generated by piezo devices (50Hz vibration) is 3.189 W / square meter.

Read more here: https://www.allaboutcircuits.com/news/californias-piezoelectric-energy-harvesting-aims-turn-traffic-green-energy/