Alternative fuels engineers design and develop systems, components, motors, and equipment which replace the use of conventional fossil fuels as main power source for propulsion and power generation with the feature of using renewable energies and non-fossil fuels. They strive to optimise energy production from renewable sources and reduce production expenses and environmental strain. The alternative fuels employed mainly include Liquefied Natural Gas (LNG), Liquefied Petroleum Gas (LPG), biodiesel, bio-alcohol as well as electricity (i.e., batteries and fuel cells), hydrogen and fuels produced from biomass.