Until about twenty years ago energy sustainability was thought of simply in terms of availability relative to the rate of use. Today, in the context of the ethical framework of sustainable development, including particularly concerns about global warming, other aspects are equally important.
The concept of energy sustainability encompasses not only the imperative of securing adequate energy to meet future needs, but doing so in a way that (1) is compatible with preserving the underlying integrity of essential natural systems, including averting dangerous climate change; (2) extends basic energy services to the more than 2 billion people worldwide who currently lack access to modern forms of energy; and (3) reduces the security risks and potential for geopolitical conflict that could otherwise arise from an escalating competition for unevenly distributed energy resources.
Characteristics of the Ideal Energy Source:
1. Sustainable (renewable). 2. Non-polluting. 3. Not dangerous to people or the planet. 4. High-grade energy useful for any purpose. 5. Silent. 6. Supplies power where it is needed (no need to transport energy). 7. Most available at peak demand time, this is frequently a hot, sunny summer day. 8. Has additional benefit of creating the building envelope (displaces conventional building materials). 9. High reliability. 10. No moving parts. 11. No maintenance required. 12. Modular (can come in any size required). 13. Low operating cost. 14. Low initial cost. 15. Supplies energy all the time. (lechner. 2001)