Can alternative energy replace fossil fuels?

John Whitehead of Environmental Economics answers in 138 words:

It all depends on how the definition of “effective” is applied in this context. According to Dictionary.com, effective means “adequate to accomplish a purpose.” If the purpose of alternative energy, such as wind and solar, is to provide a substitute for nonrenewable energy, such as oil and coal, then it can be effective. The problem facing proponents of alternative energy is that it is more costly to produce. If oil and coal were priced appropriately, incorporating all of the external costs of production and consumption such as air pollution and long-term climate change, then alternative energy would appear more competitive. However, potential supplies of wind and solar don’t appear to be large enough to completely replace oil and coal in the foreseeable future. If that is the purpose, then no, alternative energy can not effectively replace fossil fuels.

Since I post a lot on climate change, I am going to claim this as my post on climate change for Blog Action Day 2009 - see here for a complete listing of my thoughts.