A gas generator usually refers to a propellant mixture, often similar to a soli rocket propellant, that burns to produce large volumes of gas. It is similar to a rocket propellant, but is usually designed to produce large volumes of cool gas, instead of maximizing the energy available. The low temperature allows the gas to be put to use more easily in many applications. Gas generators are used to power turbopumps in rocket motors, to deploy airbags, and in other cases where large volumes of gas are needed, and storing it as a pressurized gas is undesirable or impractical.