1.1 Defining sustainable and renewable energy
Concerns about the ‘sustainability’ of humanity’s use of fossil and nuclear fuels have been a major catalyst of renewed interest in the renewable energy sources in recent decades. A sustainable energy source can be defined as one that:
- is not substantially depleted by continued use
- does not produce significant pollution or other environmental problems
- does not cause health hazards or social injustices.
In practice, few energy sources come close to these ideals, but renewable energy sources are generally more sustainable than fossil or nuclear fuels: they are essentially inexhaustible, and their use usually involves fewer health hazards and much lower emissions of greenhouse gases and other pollutants.
So, where do renewable energies come from, and why the renewed interest?