Chapter 10. RENEWABLE ENERGY SOURCES
Free energy is everywhere around us, and it is in unlimited supply. Due to some technological restrictions we are still pay for it, but with technological progress accelerating, it becomes less and less expensive. It is another issue, that some of us do not care much, and routinely prefer to stay with familiar energy consumption trends, i.e. relaying on nonrenewable sources (which are running out fast). Nevertheless, economic realities are tough, and switch to renewable energy is the only long-term scenario for human civilization. The sooner we understand that, the easier this transition can be, and the smaller environmental damage we carry. Objective laws of Nature (including laws of thermodynamics), not anybody's opinions explain why it is so.
USA Energy Consumption & Efficiency
Renewable Energy Explained (US EIA)