Sustainable energy refers to the use of any type of energy that can meet demands without putting the resources in danger of running out. It is derived from resources that can maintain current operations without jeopardizing the energy needs or climate of future generations. Sustainable energy is the answer to our energy needs because it includes any energy source that cannot be depleted and can remain viable forever. It does not need to be renewed or replenished, and it meets our demand for energy without any risk of going bad or running out.

The concept of sustainable energy is closely related to the concept of sustainable development, which is defined as meeting "the needs of the present without compromising the ability of future generations to meet their own needs". Sustainable energy development has focused on emissions and on energy security, but since the early 1990s, the concept has broadened to encompass wider social and economic issues.

Renewable energy sources are essential to sustainable energy, as they generally strengthen energy security and emit far fewer greenhouse gases than fossil fuels. Renewable energy projects sometimes raise significant sustainability concerns, such as risks to biodiversity when areas of high ecological value are converted to bioenergy production or wind or solar farms.

In summary, sustainable energy is energy that meets the needs of the present without compromising the ability of future generations to meet their own needs. It is derived from resources that can maintain current operations without jeopardizing the energy needs or climate of future generations. Renewable energy sources are essential to sustainable energy, and they emit far fewer greenhouse gases than fossil fuels.