Answer
The sun is the source of the energy that is present in wood, oil and coal. The descriptions "renewable" vs. "nonrenewable" refer to how long it takes for a source of energy to be replenished by the sun.
A grove of trees can grow relatively quickly, so wood is a "renewable" resource. The natural processes that produce oil and gas take many millions of years, and hence energy produced from those resources is "nonrenewable".