Con to the question "Can Alternative Energy Effectively Replace Fossil Fuels?"
"In a free market, cost dictates energy choices. Fossil fuels, for example, are economically attractive for many applications because the energy available from fossil fuels is highly concentrated, easily transportable, and cheaply extracted. Renewable energies such as wind and solar power, on the other hand, are relatively dispersed, difficult to transport, and costly to harness given the capital costs of facility construction.
Many people recommend accelerated federal subsidies and preferences for renewable energy in order to reduce America's dependence on imported oil. But such recommendations fail to appreciate the fact that energy sources are often difficult to substitute for one another. Until we see major technological advances in electric-powered vehicles and related battery systems, for example, technological breakthroughs in solar or wind power will have little, if any, impact on oil imports. That's because renewable energy is used primarily to generate electricity and cannot be used directly in transportation to replace oil: in 2002, only 2.5 percent of America's total electricity was generated from oil combustion."
"Energy," The Concise Encyclopedia of Economics, Ed. David Henderson, 2007