An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge.

Elastic energy is the mechanical potential energy stored in the configuration of a material or physical system as it is subjected to elastic deformation by work performed upon it.

Waste or exhaust products from the combustion of fuels.

Efficient energy use, sometimes simply called energy efficiency, is the goal to reduce the amount of energy required to provide products and services and can also reduce effects of air pollution.

Efficiency is the ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result.

A measurement of a resource’s ability to produce energy when the grid is most likely to experience electricity shortfalls.

Effective dose is a dose quantity in the International Commission on Radiological Protection (ICRP) system of radiological protection.

The amount of heat energy received at any location on the globe is a direct effect of Sun angle on climate, as the angle at which sunlight strikes Earth varies by location, time of day, and season due to Earth's orbit around the Sun and Earth's rotation around its tilted axis.

The world's first coal-fired power station generating electricity for public use. It was built at number 57 Holborn Viaduct in central London, by Thomas Edison's Edison Electric Light Company.

Eddy-current testing is one of many electromagnetic testing methods used in nondestructive testing (NDT) making use of electromagnetic induction to detect and characterize surface and sub-surface flaws in conductive materials.

Economisers are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid.

A volume of gas may be too remote from a market for natural gas, making construction of a pipeline prohibitively expensive or in a region where demand for gas is saturated, and the cost of exporting gas beyond this region is excessive.

The benefit of providing a service or making improvements to a service or system.

Part of the three sustainability pillars, the pillar that focuses on profitability through good practices and governance.

Economic geology is concerned with earth materials that can be used for economic and/or industrial purposes.

Backfeeding also exists in other instances where a location that is typically a generator becomes a consumer.

The Internet of things describes the network of physical objects, a.k.a. "things" that are embedded with sensors, software, and other technologies for the purpose of connecting and exchanging data with other devices and systems over the Internet.

The International Solar Energy Society (ISES) is a global organization for promoting the development and utilisation of renewable energy.

The International System of Quantities (ISQ) consists of the quantities used in physics and in modern science in general, starting with basic quantities such as length and mass, and the relationships between those quantities.

International Renewable Energy Alliance (REN Alliance) is a formal partnership entered into on 4 June 2004 by five non-profit international renewable energy organisations.