Pave with them. Make them into the floors of everything.
Capturing the Power of Trillions of Footfalls: "Redmond's unique floor tiles generate electricity using a phenomenon known as piezoelectricity – electricity generated by applying mechanical stress to certain materials like the lead zirconate plates in the POWERleap. When these 2-inch by 1-inch piezoceramic plates are bent, a charge is produced that can be harnessed. Multiply one tile by the surface area of a subway station or even your standard grocery store floor, and you can imagine the amount of energy these tiles have the potential to generate."