A feed-in tariff (FIT, FiT, standard offer contract, advanced renewable tariff, or renewable energy payments) is a policy mechanism designed to accelerate investment in renewable energy technologies by offering long-term contracts to renewable energy producers. This means promising renewable energy producers an…

A power purchase agreement (PPA), or electricity power agreement, is a long-term contract between an electricity generator and a customer, usually a utility, government or company. PPAs may last anywhere between 5 and 20 years, during which time the power purchaser buys energy at a pre-negotiated price.

The 1979 oil crisis, sometimes referred to as the second oil crisis (in reference to the 1973 oil crisis), refers to the drop in oil production in the aftermath of the Iranian Revolution that led to an energy crisis in 1979. Although the global oil supply only decreased by approximately four percent, the oil markets'…

An energy transition (or energy system transformation) is a major structural change to energy supply and consumption in an energy system. Currently, a transition to sustainable energy is underway to limit climate change.

Renewable energy (also called green energy) is energy made from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, bioenergy/biomass, and hydropower.

NRG Energy, Inc. is an American energy company, headquartered in Houston, Texas.

Geothermal energy is thermal energy extracted from the Earth's crust. It combines energy from the planet's formation and from radioactive decay.

Constellation Energy Corporation is an American energy company headquartered in Baltimore, Maryland. The company provides electric power, natural gas, and energy management services.

Open energy-system models are energy-system models that are open source. These models can also be known as open energy models or open-source energy-system models or some combination thereof.

Octopus Energy Group Limited (formerly Octopus Energy Limited and Octopus Energy Holdings Limited), known as Octopus Energy, is a British company operating in the fields of energy generation and supply. It was founded in 2015 with the backing of Octopus Group, a British asset management company.