Alternative Fuels

Alternative fuel refers to any any materials or substances that can be used as fuels, and are not derived from conventional sources (such as fossil fuels).  Today, more than a dozen alternative fuels are in production or under development, however, the following are commonly used and commercially available fuel sources: biodiesel, ethanol, natural gas, propane, and hydrogen

The implementation of these fuels, in place of conventional fuels, is integral to reducing emissions and our dependence on foreign oil.

Biodiesel

Biodiesel is a vegetable oil-based fuel that runs in diesel engines.  It is produced from renewable sources such as new and used vegetable oils and animal fats, and is a cleaner-burning replacement for petroleum-based diesel fuel.  Vehicles made before the mid 90s may need upgraded fuel lines to run biodiesel as it eats through certain types of rubber. Studies have shown that minimal amounts of biodiesel reduces engine wear due to biodiesel's lubricity.

Since biodiesel can be made domestically, it reduces our dependence on foreign oil. Biodiesel is also sustainable, non-toxic, renewable and nearly carbon-neutral, so it also reduces harmful emissions. However, biodiesel creates smog-producing NOx. Proponents say that the increase in NOx is mostly offset by the reduction in other emissions and greenhouse gasses.

Biodiesel can be blended with regular diesel or run 100% biodiesel. Like pure ethanol, 100% biodiesel fuel(B100) can be problematic in winter conditions. Biodiesel begins to gel under 32°F. Adding a little regular diesel into the mix helps the gel point to drop considerably. For example, in a 15% regular diesel-biodiesel blend (B85) the gel point is -15°F.

Biodiesel conversion kits typically include a heating unit to handle 100% biodiesel.

Ethanol

Ethanol is a renewable fuel made from various plant materials, called "biomass."  Ethanol contains the same type of alcohol found in alcoholic beverages.  Nearly half of U.S. gasoline contains a low-level amount of Ethanol in order to oxygenate the fuel and reduce air pollution.

Ethanol is also available as a E85, a "flex fuel," available for use in Flex-Fuel Vehicles (FFV), which can use a blend of up to 85% ethanol.  FFV's usually don't experience any loss in performance but, since ethanol contains less energy per volume than gasoline, typically get 25-30% fewer mpg's when using E85.

The ethanol supply chain consists of the following: Biomass feedstocks are grown, then various logistical systems are used to collect and transport them to ethanol production facilities, where the ethanol is produced and distributed to fueling stations.  A gallon of ethanol contains less energy when burned than a gallon of gasoline, however, the lifecycle of emissions from seed to tailpipe depends upon how the ethanol is made, and what it is made of.  The best ethanol, sustainably produced, can have less global warming pollution than gasoline.  However, the worst ethanol can increase lifecycle global warming pollution compared to gasoline.

Either way, the Department of Energy states that studies have estimated ethanol and other biofuels could potentially replace 30% or more of U.S. gasoline demand by 2030.

Natural Gas

Natural gas is a domestically produced alternative fuel and is a naturally occurring hydrocarbon gas mixture.  It consists primarily of methane, with up to 20 percent concentration of other hydrocarbons such as ethane, propane, nitrogen, helium, carbon dioxide, hydrogen sulfide, and water vapor.

Natural gas is used in many applications and is an important heating source, however, Compressed Natural Gas (CNG) has gained a lot of traction as an alternative fuel source.  CNG is cleaner than traditional gasoline and diesel fuels, and can achieve roughly the same gas mileage as a gasoline-fueled vehicle.  Natural gas produces fewer CO2 emissions, as well as far lower amounts of sulfur dioxides and nitrous oxides than any other fossil fuels.

Although CNG is a cleaner alternative to gasoline and diesel, the extraction process of hydraulic fracturing, or "fracking," has become highly controversial.  Fracking consists of forcing millions of gallons of highly pressurized water mixed with sand, and proprietary chemicals into a well.  This pressure fractures the shale and props open fissures, enabling natural gas to flow more freely out the well.  Unfortunately, the potential contamination of ground water, risks to air quality, the potential migration of gases and chemicals to the surface, and the potential mishandling of waste as a result of fracking creates environmental concerns over natural gas exploration.

Propane

No, it isn't just used to cook your burgers and hot dogs.  Propane, or liquified petroleum gas, is also used as a fuel for vehicles with internal combustion engines.  Stored under pressure inside a tank, propane turns into a colorless, odorless liquid.  As pressure is released, the liquid propane vaporizes and turns into gas, used for combustion.  Propane decreases carbon dioxide emissions by about 35% when compared to gasoline. Propane use is on the rise in the United States as it is a greener fuel, cheaper than gasoline, and a domestic fuel (90% of all U.S. propane is produced in the domestically).

Hydrogen

We saved the best for last.  Hydrogen, which has the power to revolutionize transportation and our energy infrastructure, is the simplest and most abundant element in the universe.  Hydrogen can be used to fuel internal combustion engines and fuel cells, both of which can power low, or zero-emissions, vehicles.  Hydrogen can be produced from several diverse resources including fossil fuels, nuclear energy, biomass and other renewable energy technologies.  The environmental impact of this fuel source depends on how it is produced.
The drawbacks of hydrogen use is low energy content per unit volume, high tank weight, very high storage vessel pressure, and the lack of infrastructure needed to produce, transport, and store hydrogen fuel for filling stations.
Honda introduced the FCX Clarity, a hydrogen fuel cell vehicle, in 2008, which offered zero emissions, 5 minute refueling times, and long range capabilities.  Although hydrogen on a mass scale would require an enormous initial investment, the return would be virtually pollution-free transportation and independence from foreign petroleum.