Clean Energy

Clean energy is an informal term used to refer to low- or zero-emission energy sources, and is generally synonymous with renewable energy (as used in this article). Renewable energy resources include wind and solar energy, and are distinguished from nonrenewable resources by the time frame upon which they are available. Thus, renewable energy resources are continuously available when viewed from the perspective of human time scales of thousands of years. On the other hand, nonrenewable energy sources, such as fossil and nuclear fuels, are finite because the time scales required for them to form, namely millions of years, are much greater than human dimensions. Another way of considering this distinction is to look at the respective rates of supply and demand: at current rates of ...