It is made from a blend of crushed rock, rubber and polyurethane, a synthetic plastic that replaces bitumen as the binding agent and allows even bigger pores in the road surface.

ECONOMIST: Quieter traffic: When the rubber hits the road | The

Cox stumbled across the idea at his previous company, Green Foam Blanks, which makes surfboard blanks (the foam core of a surfboard) from recycled polyurethane waste.

FORBES: Wipe Up

The hull of the boat looks a good deal like a boogie board, built from polyurethane.

ENGADGET: Platypus airboats have a Nexus S for a brain, we go eyes-on (video)

The typical surfboard is a slab of petroleum-spawned polyurethane slathered in layers of toxic polyester resin.

FORBES: Surfing's Toxic Secret

The stuff is put through a strainer to remove random debris, then sucked via tubes into a vacuum system that blends it with other polyurethane scraps recovered from car dashboards and shipping materials.

FORBES: Wipe Up

For half a century that has meant building boards out of polyurethane, which accounts for about 74% of the market.

FORBES: Surfing's Toxic Secret

The same physical properties that make polyurethane good for riding waves also make it a heck of a sponge.

FORBES: Entrepreneurs