Biodiesel is a fuel made from vegetable oils or animal fats. It provides similar fuel economy and horsepower to petroleum diesel and has many environmental and safety advantages. Biodisel can power any diesel (not gasoline) engine.

Biodiesel is a clean-burning 100% renewable fuel. It is made in America and can be made from a variety of plant and animal fats (as well as many waste grease products). Thus, biodiesel shifts our economic reliance from unstable foreign fuel sources to American farmers, ranchers, and in our case, urban waste streams.

Bronco Biodiesel plans to provide biodiesel to public fleets in the Kalamazoo area and develop greener technologies for biodiesel production. We are also working to elucidate regional waste-grease ordinance structures.

Biodiesel from Trap Grease

Our focus is on recovering trap grease from commercial kitchens to convert it into biodiesel that meets all industry and government quality specifications. Using this process, we are not using virgin vegetable oils and are thus not competing with agricultural food production to create biofuels.

How does it work?
As a byproduct of food processing and preparation, cooking grease collects in plumbing traps and interceptors that must be pumped on a regular basis, in accordance with state and local codes. The resulting liquid waste is typically processed by commercial haulers and then disposed of — fats bound with solids are sent to landfill and separated water is returned to the sewer system. This grease often goes unused, but is a resource for sustainable, renewable biodiesel. Trap grease has great potential as a biodiesel feedstock — it is comprised of both triglycerides and free fatty acids. In Kalamazoo, we estimate that it could power 4,000,000 vehicle miles per year. Nationally, biodiesel from trap grease could yield 600,000,000 gallons per year (Dept. of Energy estimates). However, collection, processing, and efficient conversion into high-quality fuel pose significant challenges that we have begun to address.

Solving problems
Poorly maintained grease traps cost American cities millions of dollars a year in line blockages and breaks. At wastewater treatment plants, greases suffocate the organisms that decompose sewage. By recovering the waste that grease traps catch, Bronco Biodiesel is playing a part in solving these local problems.

Virgin oil and "yellow grease"
Biodiesel is often produced using virgin soybean or rapeseed oil. Due to the many problems inherent in using these feedstocks, Bronco Biodiesel does not use virgin oil. Growing vast amounts of vegetable oil for fuel can result in increased fertilization, pesticide use, harmful land use, and additional pressure on food markets. "Yellow grease" is reused vegetable oil that is discarded after making fried foods. Yellow grease, unlike trap grease, is already being used in a variety of commercial applications to produce new goods. However, trap grease has little commercial value and is expensive to regularly dispose of in landfills. We use trap grease to tap into potential energy that is not already being commercially exploited.

Biodiesel Properties

Biodiesel's properties as a fuel are similar to petroleum diesel (petro-diesel), so it can be used interchangeably with petro-diesel or mixed with petro-diesel for use in unmodified conventional diesel engines.

  • Lubricity is significantly higher than petro-diesel, which prevents wear in fuel system components and increases engine life span.
  • Flash Point is higher than petro-diesel, making the fuel safer for storage and transport.
  • Density is comparable to petro-diesel.
  • Viscosity is approximately 1.5 to 2 times as high as petro-diesel.
  • Cetane number is higher than petro-diesel, which means it burns more completely, resulting in more power, better engine performance, and lower emissions.
  • Cold flow properties are not as desirable as petro-diesel, but blending and other treatments rectify this issue.
  • Oxygen content reduces particulate matter, hydrocarbon, and carbon monoxide emissions and increases efficiency.
  • Energy density, while slightly lower than petro-diesel, results in increased or equal fuel economy (due to efficiency and lubricity benefits).
  • Sulfur content is lower than the 2007 federal ultra-low sulfur diesel requirements.

Biodiesel Blending

Biodiesel is most commonly mixed in a ratio of 20% biodiesel: 80% petro-diesel. The 20:80 blend is commonly referred to as “B20.” Similarly, other blends are referred to by including a “B” followed the percentage of biodiesel in the mixture (e.g. a 5% biodiesel: 95% petro-diesel blend would be “B5”). In the past few years, the biodiesel industry has grown exponentially. Over 600 fleets in the United States now operate on biodiesel fuel (or some blend of biodiesel greater than B2). Washington and Minnesota recently passed laws mandating that all diesel fuel sold must contain at least 2% biodiesel (B2). A current bill in the Michigan legislature would require all diesel fuel sold in Michigan to include at least 2% biodiesel.

Environmental Benefits

In addition to being a renewable resource and reducing petroleum dependency, particularly from foreign sources, biodiesel has a number of beneficial environmental characteristics. Because it is non-flammable, as biodegradable as table sugar, and no more toxic than table salt, its use can significantly decrease stormwater problems stemming from pollution runoff from roads and parking lots. Additionally, as an oxygenated fuel, biodiesel reduces incomplete combustion and thus reduces the production of many harmful air pollutants. The National Renewable Energy Laboratory says that a 20% blend of biodiesel (B20) will significantly reduce tailpipe emissions (relative to pure biodiesel) accordingly:

  • 30% reduction in carbon monoxide emissions
  • 40% reduction in hydrocarbon emissions
  • 25% reduction in particulate emissions
  • 20% reduction in carbon dioxide emissions
  • 20% reduction in sulfur emissions