What is Biodiesel and How Does It Work?

April 28, 2016

As alternative fuels for cars are making more and more headlines, the term biodiesel is being tossed about. Some of us know what it is and some of us don’t, but how many actually understand what makes biodiesel work, how it’s different from other alternative fuel sources, and why it’s better for the environment.

Biodiesel isn’t actually Diesel Fuel

Let’s start at the beginning: biodiesel isn’t actually diesel fuel at all.  It’s not even petroleum-based the way most fuels (gasoline, diesel, natural gas) are. It is sometimes blended with petroleum fuels to create a biodiesel blend. Biodiesel is an alternative fuel produced from vegetable oils such as soybean oil or canola oil. It is currently the only alternative fuel that fully meets the health testing requirements of 1990 Clean Air Act.

Biodiesel’s Use and Availability

While not readily available throughout the U.S. at this time, biodiesel is the first commercially produced alternative fuel product to be made entirely in the U.S.  Used in its pure form, biodiesel has lower emission than other fuels, but biodiesel blends are also available. Specifically, using a 100% biodiesel reduces carbon dioxide emissions by 75 percent as opposed to a 20 percent biodiesel blend which reduces carbon dioxide emissions by only 20 percent.  Despite not being readily available in most U.S. states, biodiesel doesn’t require the creation of new or additional infrastructure in order to support it the way something like hydrogen fuel would. Existing gasoline tanks could be outfitted or repurposed to support the storage and pumping of biodiesel fuels.
Another benefit to biodiesel is that it doesn’t pose any new or additional safety risks. Biodiesel has a considerably higher flashpoint- the temperature at which it turns into a combustible vapor – than traditional gasoline. Biodiesel’s flashpoint rests at temperatures greater than 233 degrees Fahrenheit versus traditional gasoline at -57 degrees Fahrenheit. Traditional petroleum based diesel’s flashpoint is at 147 degrees Fahrenheit. This means that biodiesel is considerably less dangerous to transport and handle. Speaking of transporting, another benefit to using biodiesel is that, in the event of a spill, it is easier to clean than petroleum products and less hazardous to wildlife.

One downside to biodiesel is that it begins to gel, or solidify, at low temperatures which could pose a problem for cold-weather transport and storage, particularly in northern parts of the country or in areas that frequently see low temperatures. In order to make biodiesel viable in cold-weather environments a special fuel system would need to be created just to run them in cold weather.

Economic Effects of Biodiesel

Biodiesel does pose one very unique problem. Since the raw materials used to create it are also food sources, an increase in production of these food sources for use in the making of biodiesel will decrease the availability of that food product for use as food. This can drive food prices up as we saw happen with the price of corn after the government implemented the addition of ethanol to gasoline throughout the US.

Based on pricing info from the E.U. where biodiesel is more common than in the U.S., the cost of biodiesel is often more expensive than petroleum-based diesel. There are a number of things that affect the cost of biodiesel including the plants used to produce the oil, as well as how the area growing the plants maintains the ratio of food use plants to fuel use plants.

Some plants are better for biodiesel than others

Biodiesel in the U.S. has largely been produced using soybean oil. However, there are other plants being used in other parts of the world that have a high output of oil and use fewer resources. The top plant being studied for development in U.S. biodiesel production is a plant called pongamia. The pongamia seed is roughly 40 percent oil, which means a higher crop yield, which in turn means a greater yield via a smaller supply. This suggests that a higher production volume is possible using less farmland. Another plant that is currently being used in Malaysia to help support the E.U. demand for biofuel is a shrub-like tree called Jatrophas.

Other sources of biodiesel

Because biodiesel is made from oils extracted from various plant materials, there’s a wide range of plants that are capable of producing biodiesel. Some of the plants getting the most attention for their ability to produce energy dense oils and high volumes of oil include:

  • Fungus
  • Algae
  • Coffee Grounds
  • Discarded Alligator Fat (as waste from the skinning/ leather-making industry. Roughly 15M lbs produced annually).

Can I Use Biodiesel in My Car?

It’s not likely. Biodiesel caught everyone’s attention when it was discovered that older diesel engines produced by Mercedes were able to run on the environmentally friendly fuel. The problem is, most cars can’t do this and doing it can void your warranty. Biodiesel doesn’t play nicely with numerous components common in today’s cars including any copper alloy, a number of common plastics, and certain kinds of rubber. So if you’re interested in using a biodiesel vehicle, then it’s best to buy a vehicle equipped to use biodiesel fuel.

Biodiesel Compatible Cars in the U.S.

There isn’t an abundance of biodiesel ready cars in the U.S. since only a few metropolitan areas are equipped with the infrastructure to support them. Still, for the 2013 and 2014 model years American car manufacturers are doing their part. U.S. drivers can expect biodiesel compatible cars from Dodge, Chrysler, and Chevrolet. The only caveat being that these cars will run on B20- a biodiesel and petroleum fuel blend that is made up of only 20 percent biodiesel. There are not currently any mass-produced 100 percent biodiesel cars ready for purchase in the U.S. for the 2013 to 2014 model years, but if infrastructure continues to grow and research into biofuel sources proves valuable, then we should expect to see a growing availability of biodiesel at the pump.


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