Energy efficiency

Energy efficiency may refer to:

Efficient energy use, the goal to reduce the amount of energy required to provide products and services

Energy efficiency in transportation

Energy efficiency in transportation

Energy conversion efficiency, the ratio between the output and input of an energy conversion machine

Energy conservation, efforts made to reduce energy consumption

Sustainable energy

Sustainable energy is energy obtained from non-exhaustible resources. By definition, sustainable energy serves the needs of the present without compromising the ability of future generations to meet their needs. The organizing principle for sustainability is sustainable development, which includes the four interconnected domains: ecology, economics, politics and culture.Sustainability science is the study of sustainable development and environmental science.

Technologies that promote sustainable energy include renewable energy sources, such as hydroelectricity, solar energy, wind energy, wave power, geothermal energy, bioenergy, tidal power and also technologies designed to improve energy efficiency. Costs have fallen dramatically in recent years, and continue to fall. Most of these technologies are either economically competitive or close to being so. Increasingly, effective government policies support investor confidence and these markets are expanding. Considerable progress is being made in the energy transition from fossil fuels to ecologically sustainable systems, to the point where many studies support 100% renewable energy.