David Thornton is the organics and biofuels project coordinator for Clemson University Facilities.

David Thornton is the organics and biofuels project coordinator for Clemson University Facilities.
Image Credit: Jim Melvin / Clemson University

CLEMSON – In the scientific community, opinions vary as to when human beings will finally use up Earth’s underground reserves of petroleum. Thirty years? Fifty years? One hundred years?

Though the timing is debatable, the outcome is not. At 7.3 billion people and growing, the human race will eventually deplete the world’s fossil fuels. Without viable alternatives firmly in place, chaos would result.

One alternative is biofuel, which is broadly defined as a fuel produced directly or indirectly from plant materials and animal waste. The result is a recycled product that is friendly to the environment.

Examples include:

  • Biodiesel, which is made from vegetable oils and animal fats
  • Ethanol, which is most often made from corn or sugarcane
  • Green diesel, which is derived from algae and other plant sources
  • Methane, which is derived from animal manure and other digested organic material

“Biodiesel production in the U.S. is increasing at a record pace, with 1.1 billion gallons being produced annually,” said David Thornton, the organics and biofuels project coordinator for Clemson University Facilities. “And this is expected to continue to increase as researchers develop more productive and sustainable oil sources. Diesel fuel is mainly used in agriculture, military and transport of goods. Currently, biodiesel has the potential to displace about 15 percent of diesel fuel used in the U.S.”

Thornton, who is also the composting facilities manager with the recycling program at Clemson, recently conducted a workshop on making your own biodiesel.

During his daylong workshop, Thornton demonstrated the process of making biodiesel, which involves a combination of heat, agitation and time. He also focused on essential safety and quality-control monitoring procedures designed to produce clean domestic fuel using cooking oil collected from Clemson’s campus cafeterias.

The cooking oil is first settled in tanks, which allows unwanted debris – called “gravy” – to sink to the bottom. The cleaner oil nearer the surface is then pumped into a reactor, where it is mixed with methanol and a catalyst. This process removes a thick alcohol from the vegetable oil molecules and replaces it with a lighter methyl alcohol to decrease the viscosity of the fuel, thus making it a drop-in replacement for ordinary diesel fuel. Further purification and filtering eventually result in a fuel that is fluid, moisture-free and ready for use in cars, tractors and any machines powered by diesel engines.

Biodiesel has many mechanical advantages in diesel engines.

“Second-generation biodiesel feedstock such as algal and insect oils are on the horizon,” Thornton said. “These feedstocks can revolutionize fuel production by using non-arable land and industrial wastes to produce renewable energy and sustainable animal proteins, while at the same time not competing with food markets like their predecessors such as soybeans and corn.”

Most of the organic waste produced at the university is processed at the Cherry Crossing Research Facility, where it is made into mulch, compost, animal feed and biofuel that is used on campus and also available for purchase.

“We recycle food waste, landscape residuals, agricultural residuals and even some construction debris,” Thornton said. “And eventually we’re going to be tackling bio-solids, which are the byproducts from anaerobic digesters at wastewater treatment plants. We also have a small lab that’s being built, so by this time next year we hope to be converting waste plant and animal materials into natural gas.”

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