The one natural resource that the world has left in infinite quantity is human ingenuity.

ECONOMIST: We are all innovators now

Like wind and sunlight, the power of gravity is an infinite resource.

FORBES: Gravity May Soon Qualify As Renewable-Energy Resource in New York

He shows that if we have strict environmental resource limits then we cannot have infinite expansion of the physical side of the economy.

FORBES: Biofuels: Policy Based Evidence Making