Gasoline and Diesel – Traditional hydrocarbons offer very high energy per kilogram and can be refueled quickly, making them difficult to replace. However, they produce significant amounts of carbon and other pollutants when used.
Compressed Natural Gas – CNG works much like traditional hydrocarbons, offering the same high energy per kilogram and rapid fueling, while producing somewhat less carbon and other pollutants. Unlike traditional hydrocarbons, where fueling stations are on every corner, CNG stations are much less common, and other CNG infrastructure is also lacking. Converting vehicles to run on CNG instead of gasoline is an expensive process.
A container used to store compressed natural gas.
Ethanol and Other Biofuels – Biofuels also produce carbon and other emissions when used, but growing them absorbs carbon, making the net carbon output of biofuels less than that of gasoline. Biofuels are grown as crops, making them renewable – but also expensive and use significant amounts of land.
Conventional Batteries (Electrochemical Cells) – All fuels that are burned produce carbon, so electricity is a natural choice for alternative vehicles, but the traditional storage for it is highly problematic. Although batteries do not pollute when used, they often contain toxic chemicals. Batteries take a long time to charge and cannot release energy quickly. Batteries also have a very have low energy density, and although these disadvantages are being worked on, batteries remain highly impractical compared to hydrocarbons.
A standard battery used to power a vehicle.
