Energy Generating Parking Lot

A supermarket in England is installing a parking lot that will generate power as cars drive by.  The system works by a series of underground plates that, when driven over, create a rocking motion that powers generators.  The generators create about 30KW of energy per hour.  The supermarket plans on using the power to run their lights and cash registers.

Seems expensive, will have to see if it makes more sense than solar.  Hope the idea works and finds mass adoption.