This document discusses non-renewable resources. It defines non-renewable resources as those that do not replenish themselves quickly enough to be considered sustainable. Examples given are fossil fuels like coal, petroleum and natural gas. It notes that these fuels were formed over millions of years from ancient organic materials. In contrast, renewable resources like sustainably harvested timber and wind power can replenish on human timescales. Fossil fuels are difficult to obtain but provide large amounts of energy. The top oil and gas producing countries are also listed. Nuclear fuels obtained from uranium mining are also considered non-renewable but can generate energy cleanly. Non-renewable resources are finite and will eventually be depleted as they cannot repl