Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable (adjustable on demand) due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable energy sources, such as dammed hydroelectricity or…

Grid energy storage, also known as large-scale energy storage, is a set of technologies connected to the electrical power grid that store energy for later use. These systems help balance supply and demand by storing excess electricity from variable renewables such as solar and inflexible sources like nuclear power,…

California produces more renewable energy than any other state in the United States except Texas. In 2018, California ranked first in the nation as a producer of electricity from solar, geothermal, and biomass resources and fourth in the nation in conventional hydroelectric power generation.

Canada has access to all main sources of energy including oil and gas, coal, hydropower, biomass, solar, geothermal, wind, marine and nuclear. It is the world's second largest producer of uranium, third largest producer of hydro-electricity, fifth largest natural gas producer, and the fifth largest producer of crude…

A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by using the photovoltaic effect. It is a type of photoelectric cell, a device whose electrical characteristics (such as current, voltage, or resistance) vary when it is…

Energy in the United States is obtained from a variety of sources, although the majority came from fossil fuels in 2025: 37% of the nation's energy originated from petroleum, 36% from natural gas, and 9% from coal. Electricity from nuclear power supplied 9% and renewable energy supplied 9%, which includes biomass,…

Grupo Opaia SA is a holding company operating under Angolan law based in Luanda, Angola, running projects in civil construction services, solar energy technology, drinking water systems, hotel service and tourism, agriculture, finance and more. It was founded by the Angolan Agostinho Kapaia, from Huambo, in 2002.

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'…

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

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.