FREMONT, CA: Liquid fossil fuels are convenient and economical, but engines can run on various fuels. Alternative fuels have been available for as long as internal combustion engines have been around. Wood gas-powered vehicles, for example, were commonly employed during World War II. This helped people to save fuel for the war effort. Wood gas was produced from the incomplete combustion of wood chips.
The operation would take place in a large kettle. The kettle might be mounted on a trailer behind a vehicle and then piped to the engine. Today, few vehicles run on wood gas, but several other alternative fuels are available, and numerous more are under development. Some, such as compressed natural gas (CNG) and liquid petroleum gas (LPG—a mixture of propane and butane), are made from fossil fuels. Others, including renewable diesel, biodiesel, ethanol, and biogas, are derived from energy crops or organic waste.
Advances in chemical engineering and other disciplines have also enabled the synthesis of methane, hydrogen, diesel, and other compounds from non-fossil feedstocks such as carbon dioxide (CO2) and water using renewable electricity. These synthetic fuels are also known as e-fuels. Renewable diesel can be used mutually with conventional diesel.
Most engines require no modifications. Biodiesels must be blended with fossil diesel for use in standard compression ignition (CI) engines. Ethanol, or alcohol, can be utilized in traditional SI (spark ignition) vehicles when combined with gasoline. Ethanol blending is very prevalent.
Environmental compatibility: Biodiesel and renewable diesel are also biodegradable, non-toxic, and emit fewer odors. Similarly, if LPG or natural gas is spilled, it is unlikely that it will contaminate soil or water because it will just evaporate.
Shelf life: Natural gas and propane, as well as hydrogen and ammonia-based e-fuels, have an indefinite shelf life, in contrast to gasoline and diesel. This also applies to numerous modern biodiesel and synthetic diesel compositions, lasting up to ten years.
Decreased maintenance requirements: Natural gas and propane often burn cleaner than liquid fuels, allowing fewer soot particles to enter the engine oil. Some operators take advantage of this by prolonging their oil change intervals. Managing a large fleet of vehicles can result in huge savings, potentially worth tens of thousands of dollars or more.
