Every time you step on a University bus, at least 20 percent of the fuel it burns is already renewable, sustainable and domestically produced.

All University vehicles with diesel engines run on B20 biodiesel, a blend of 20 percent biodiesel and 80 percent petroleum diesel, said Renee Jordan, University Fleet Manager. Biodiesel is a diesel fuel made from soybean oil, recycled waste cooking oils, or any other vegetable oil and even oil produced by algae.

If an engine can run on petroleum diesel, it can run on biodiesel.

"Biodiesel is a renewable, sustainable, environmentally friendly option that's already a mature technology," said Steven Bertman, professor of chemistry at Western Michigan University. In order to be used, biodiesel doesn't require a huge push of research and development.

"I keep hearing 'hydrogen fuel,' keep hearing 'future,' keep hearing '2030,' " Bertman said, exasperated. "We can use biodiesel now."

Biodiesel's huge advantage as a fuel comes from its renewability. The carbon dioxide emitted by burning biodiesel was taken from the atmosphere just a year earlier, when the soybean plant removed it to photosynthesize sugars for food. This means that there is no net year-to-year change in atmospheric CO2 due to biodiesel combustion.

Increased atmospheric CO2, a greenhouse gas, is a major cause of climate change. By not producing CO2 from long-stored fossil fuels, biodiesel helps keep atmospheric CO2 from rising, mitigating climate change.

In 1895, Rudolph Diesel designed his eponymous engine to run on a variety of fuels, which include nearly any hydrocarbon from gasoline to peanut oil.

"Diesels have the advantage of being inherently more efficient," Bertman said.

This is due to the use of compression ignition, which ignites the fuel without a spark plug, and higher fuel compression ratios than gasoline engines.

However, running on biodiesel is not without problems.

"It's not a perfect solution," Bertman conceded. "It's still internal combustion, and emits carbon monoxide and nitrogen oxide."

Both compounds are pollutants that affect air quality.

"But compared to the gas engine, it's a huge step forward," he said.

An October 2002 EPA study reported that emissions from soy-based B20 biodiesel, compared to petroleum diesel, have 21 percent fewer hydrocarbons, 11 percent less carbon monoxide and 10 percent less particulate matter - the black smoke you see coming out of diesel engine tailpipes. These benefits increase with increasing amounts of biodiesel in the blend. The only downside is that nitrogen oxide emission - a key step in creating ozone pollution - increased by 2 percent.

Biodiesel challenges

Bertman said there are three major challenges to revving up biodiesel use: the availability of the biodiesel in retail locations, cold weather limitations and the supply of raw oil to be converted into biodiesel.

According to the Alternative Fuel Data Center at the United States Department of Energy, there are currently nearly three times as many biodiesel pumps in Michigan as ethanol pumps. Engines do not need to be modified for biodiesel use as they do for ethanol. Ethanol has only 60 percent of the energy density of regular gas, which means poorer fuel efficiencies, whereas biodiesel is within a few percentage points of the energy density of petroleum diesel.

At cold temperatures during Michigan winters, biodiesel, like petroleum diesel, can become more viscous and resist flow. However, these problems have been solved in petroleum diesel with additives and by the way the fuel is handled.

Bertman drives a diesel Volkswagen Jetta, and runs it year-round on B50 (a 50 percent biodiesel, 50 percent petroleum diesel blend). In the summer, when cold temperatures are not a problem, he uses 100 percent biodiesel, or B100.

He praises biodiesel for being non-flammable, biodegradable, non-toxic and an excellent engine lubricant. Many people make their own small-batch biodiesel for personal use, and Bertman often demonstrates how easy this is by making it in two-liter plastic bottles during public talks on the topic.

Biodiesel is made via a chemical reaction called transesterification. You start with fresh vegetable oil or waste grease, chemically known as triglycerides. You add methanol and, as a catalyst, potassium hydroxide. After mixing this solution, you end up with glycerine, which can be composted, and fatty acid methyl esters, also known as biodiesel. You then separate out the glycerine and heat the biodiesel to remove any unreacted alcohol and water.

Triglycerides are "nature's answer to storing solar energy," Bertman said. "They're chock full of energy."

"That's why there is oil in seeds - the plant is trying to pack as much energy in as small a space as possible."

Using cropland to cultivate seed oil for biodiesel would cause domestic fuel production to compete with food production.