Sustainability (or sustainability) is a term that can be used in different contexts, but generally refers to the quality of being able to sustain itself without outside help and without exhausting available resources.
In ecology, sustainability describes the ecological or biological systems (such as forests, for example) that maintain their diversity and productivity over time.
In the economic and social context, sustainability is defined as the ability of current generations to meet their needs without compromising future generations.
Sustainable development is used in two different contexts
Synonyms and related terms
An example of a sustainable project is the underground Monterrey, Mexico, which runs on biogas energy generated from municipal waste. In 2003 the state government of Nuevo Leon, Mexico made a partnership with a German company to harvest the methane gas produced by the process of natural decomposition in landfills. Normally this gas reaches the atmosphere as pollution, since methane is a greenhouse gas and contributes to global warming. But with the biogas program, it is intercepted before it contaminates the atmosphere and in return provides 52% of the energy needed for public lighting, Metro, several public buildings and sewer service.
This project is sustainable because it can beneficially continue without outside help and without straining the resources necessary for its operation, so you agree with the definition of sustainability.
It is important to remember that 52% is just over half of the energy needed for municipal activities, so you can not say that is completely sustainable, but it is a significant step towards energy sustainability of Monterrey step.
More information and examples of sustainability