Fossil fuel phase-out is the gradual reduction of the use and production of fossil fuels to zero, to reduce deaths and illness from air pollution, limit climate change, and to strengthen energy independence. It is part of the ongoing renewable energy transition. Current efforts in fossil fuel phase-out involve replacing fossil fuels with sustainable energy sources in sectors such as transport and heating. Alternatives to fossil fuels include electrification, green hydrogen and biofuel. Phase-out policies include both demand-side and supply-side constraints. Whereas demand-side approaches seek to reduce fossil-fuel consumption, supply-side initiatives seek to constraint production to accelerate the pace of energy transition and reduction in emissions. It has been suggested that laws should be passed to make fossil fuel companies bury the same amount of carbon as they emit.