Bookmark and Share

Biodiesel: The Clear Choice

Brittany Ekre


Biodiesel fuel, made from vegetable oil, is a viable alternative to petroleum because it:

  • is a biodegradable, eco-friendly product
  • improves engine efficiency and safety
  • provides one answer to future fossil fuel shortages

July 2002

Petroleum-based diesel engines emit pollutants.

Bus running on soybean biodiesel. Photo: U.S. Department of Energy.

Diesel is the fuel for many vehicles. Diesel engines are a type of internal combustion engine in which heat caused by air compression ignites the fuel. At the instant fuel is injected into a diesel engine’s combustion chambers, the air inside is hot enough to ignite the fuel on contact. Diesel engines therefore do not need spark plugs, which are required to ignite the air-fuel mixture in gasoline engines. Diesel engines burn a petroleum product similar to kerosene, jet fuel, and home heating oil. A major disadvantage of the diesel engine is the production of sooty, smelly, black smoke.

The many advantages of biodiesel fuel

Biodiesel is good for the economy and for the environment.

With gas prices soaring and our fossil fuel supply diminishing, most people would agree that we need to find a cheaper way to fuel our economy. Biodiesel can be a viable alternative to petroleum diesel fuel because it is:

  • made from renewable oils
  • biodegradable
  • free of sulfur and aromatics
  • cleaner for the environment
Biodiesel is made from renewable fats and oils, such as in soybeans.

In the past decade, biodiesel has been gaining worldwide popularity as an alternative energy source because of its many benefits.

  • Biodiesel is made from renewable fats and oils, such as vegetable and canola oil, by a simple refining process.7
  • One of the main commodity sources for biodiesel is soybeans, a major crop produced in many parts of the world. It is grown in 30 states in America, yielding 75.39 million metric tons in 2000.1
  • The by-product glycerin can be used as well, in products such as toothpaste, cough syrup, and plastic.5
Use of biodiesel requires little or no engine modifications.

In addition to easily-available sources, biodiesel has other major advantages:

  • “It can be used in existing engines and fuel injection equipment without negative impacts to operating performance.”2

  • It can replace or blend with petroleum diesel with little or no engine modifications.

  • Blended at a 20% rate with petroleum diesel, it has lower wear than traditional fuel and shows improved lubricity. In fact, it is the only alternative fuel “that can actually extend engine life because of its superior lubricating properties.”2

Biodiesel extends engine life and is safer.
  • Biodiesel stays blended with petroleum diesel, making it possible to store and dispense wherever diesel fuel is now stored or sold.2

  • It degrades about four times faster then petroleum diesel fuel.

  • Operationally, biodiesel has a higher flashpoint (the temperature at which diesel fuel ignites), making it a more versatile fuel than conventional diesel where safety is concerned. Due to lower volatility (tendency to vaporize) and a higher flashpoint, it is less likely to catch fire during an accident.9

The marine industry can benefit from biodiesel fuel.

According to university tests, biodiesel is a viable option for niche markets, such as urban bus fleets and the marine industry, including “recreational boats; inland commercial and ocean-going commercial ships; research vessels;”3 and coast guard fleets. For example, recreational boats consume 95 million gallons of diesel fuel annually9 and, overall, the marine industry accounts for 10% of the petroleum diesel fuel market in the United States.

Good for the environment

Biodiesel is biodegradable and has less exhaust odors.

“Pure biodiesel is biodegradable, non-toxic, and essentially free of sulfur and aromatics.”3 The use of biodiesel and biodiesel blends results in:

  • a less offensive exhaust odor, which can be a real benefit in confined spaces or large urban areas
  • no eye irritation, since biodiesel is oxygenated, resulting in engine combustion that is more complete than petroleum
  • a reduction of pollutants, such as carbon dioxide, which in turn helps to prevent depletion of the ozone layer and acid rain
Petroleum-based diesel engines contribute to air & water pollution from sulfur and hydrocarbons.

Conventional diesel causes a lot of pollution in the form of hydrocarbons (family of organic compounds composed entirely of carbon and hydrogen) and sulfur emissions (a problem with most fossil fuels).8 “There is strong environmental pressure to eliminate or at least greatly reduce these emissions, especially in areas of environmental sensitivity such as lakes and inland waterways and inner city areas.”

  • Emission of chemicals into the atmosphere depletes the ozone layer.
  • The pH level of many freshwater lakes in America has been altered so dramatically by acid rain that entire fish populations have been destroyed.
  • Sulfur dioxide emissions and sulfuric acid, even from long distances, can also damage limestone and marble.
Biodiesel provides cleaner emissions.

By contrast, biodiesel reduces the major greenhouse gas components in the atmosphere, carbon monoxide, hazardous diesel particulate, and life cycle carbon dioxide emissions — all of which are damaging to the environment.2 Biodiesel’s cleaner emissions and favorable odor are clearly an improvement over petroleum diesel.

Biodiesel’s cost could decrease if more land was allocated for growing its ingredients.
Tests show biodiesel blends perform as well as petroleum diesel.
Conclusion: Nations should invest in biodiesel research.

Cost and performance

The cost of biodiesel depends on the market price for oils. Biodiesel blended at a 20% level with petroleum diesel costs 15-30 cents per gallon more than petroleum diesel alone. However, given the other advantages of biodiesel, it is a still an option to diesel, especially “in certain niche markets that require a cleaner-burning, biodegradable fuel.”6 Costs could decrease if, for example, more agricultural land was used to grow and use crops for biodiesel ingredients.

More than 100 biodiesel demonstrations, including 1,000,000 mile tests and more than thirty 50,000 mile tests, have logged more than 30 million road miles with biodiesel blends. In these tests, performance, fuel mileage, drivability, start-up, power, range, and cold weather performance characteristics of blends were similar to petroleum diesel.10

Biodiesel still has some obstacles to overcome in addition to its high cost. “Because of its unsaturated fatty compounds, vegetable oil reacts with oxygen more easily than diesel does, and so its properties can change. Biodiesel can also leave more gummy deposits in engines than regular diesel does.”4 However, it is a worthwhile investment for nations to help biodiesel research. Biodiesel may be one major solution to ensuring future fuel supplies that are environmentally friendly.

Brittany Ekre is a high school senior from Beach, North Dakota. Her project on biodiesel fuel was entered in the Intel International Science and Engineering Fair in Louisville, Kentucky in 2001. She has earned a full four-year tuition scholarship to Drexel University, where she intends to study science.

Biodiesel: The Clear Choice

US National Biodiesel Board

Biodiesel fuel facts, general and market information, news, and links.

How Diesel Engines Work

Article about everything you ever wanted to know about diesel engines.

Alternative Fuels Data Center

One-stop shop for all your alternative fuel and vehicle information needs. This site has more than 3,000 documents in its database, an interactive fuel station mapping system, listings of available alternative fuel vehicles, links to related web sites, and much more. The site offers a phone and e-mail hot line to answer your questions.

Read a book

Joshua Tickell’s bookFrom the Fryer to the Fuel Tanktells you how any diesel engine can run on vegetable oil. Book details and purchasing info at

Vehicle Buyer’s Guides

From the US Department of Energy, this site contains extensive information for consumers and business owners considering purchasing alternative fuel or advanced technology vehicles.

Energy Sourcebooks - Lesson Plans

Lesson plans and activities for elementary, junior high, and high school students to explore alternative energy sources.

Biodiesel workshops

The VeggieVan site offers workshops in the U.S. where you can learn how to make biodiesel fuel and a biodiesel processor.

Hybrid Fleet Vehicles

The Center for the New American Dream offers a fact sheet entitled “Harnessing the Power of Advanced Fleet Vehicles: A Hybrid Electric Fact Sheet for Government Officials.” The fact sheet includes a comparison of annual emissions and fuel consumptions of mid-sized sedans, data on current and future hybrid models, and details on efforts to help local and state governments purchase hybrids.

  1. American Soybean Association. 2001. “Soy stats 2001.” Available in pdf format at Accessed 1/02.
  2. “The fuel.” Accessed 1/02.
  3. “Interesting facts about biodiesel.” Accessed 1/02.
  4. Corinna Wu. Dec. 1998. “Fill ‘er up…with veggie oil.” Science News. Accessed 1/02.
  5., Canadian Renewable Fuels Association. “Production.” Accessed 1/02.
  6., Canadian Renewable Fuels Association. “Economics of biodiesel versus petroleum.” Accessed 1/02. 9/9/09: No longer available.
  7. “Grassroots biodiesel.” Accessed 1/02.
  8. Holbrook, Jack B, “Investigating the use of vegetable oils as a fuel.” 6 pages. (Accessed 1/02; no longer available online).
  9. “Why biodiesel?” Accessed 1/02. 9/9/09: No longer available.
  10. University of Idaho. “Pioneers in biodiesel research.” Accessed 1/02. (no longer available as of 4/11/12)

General References:

  • » Marr, Wess, LLC. Personal interview re: fuel industry. 1/13/02.
  • » National Biodiesel Board - IT Division. “Biodiesel.” 11 pages. Accessed 1/02.


Understanding Science