MORE IN BIODIESEL

The term is often used broadly to refer to any plant-based, nonpetroleum fuel, but biodiesel is merely repurposed raw vegetable oil. While straight vegetable oil (SVO) and waste vegetable oil (WVO) can be used in diesel engines, doing so requires some modification to the engine and will slightly lessen engine performance. Biodiesel requires no engine modification, and it will generally improve engine performance over petroleum-derived diesel Biodiesel can be made from virgin oil (soy, canola, coconut, rapeseed, etc.), recycled vegetable oil (say, from a McDonald’s fryer), or even animal fats (fish oil, beef tallow).

Biodiesel is refined by a chemical process, transesterification, in which the oil is mixed with an alcohol, usually methanol or ethanol, and separated into methyl esters (biodiesel) and glycerin. The conversion process is a relatively straightforward one, which has led to a vibrant and widespread biodiesel homebrew movement throughout the United States and parts of Europe.

A 1998 study by the U.S. Department of Agriculture and Department of Energy found that petroleum-based (or conventional) diesel and gasoline have negative energy yields – that is, creating them uses more fossil fuel energy than they produce – whereas biodiesel yields 3.2 units of energy for every unit of fossil fuel-based energy used to create it: a 280 percent greater yield than petroleum diesel. Biodiesel also burns cleaner, emitting a net 75 percent less carbon dioxide into the atmosphere than conventional diesel. Petroleum diesel, of course, is derived from crude oil, and burning it introduces carbon that's been sequestered and essentially out of circulation for hundreds of millions of years into the already overburdened modern atmosphere. Burning plant-based biodiesel, on the other hand, releases carbon that’s been recycled from the atmosphere by plants and trees – carbon which, ideally, will be taken up again by new crops of soy, canola, rapeseed, etc. Biodiesel also produces less particulate matter, carbon monoxide, and sulfur dioxide emissions.

Biodiesel can be used unmixed, as 100 percent biodiesel, or in blends with normal diesel. Denominated Bxx: B20, the blend typically available at commercial pumps, is 20 percent biodiesel and 80 percent petrol. In cooler temperatures, however, B100 can get a little viscous under 32 degrees, leading consumers to switch to lighter blends during winter months. Blends also have commensurately higher emissions than pure biodiesel.

History

The father of the diesel engine, Rudolf Diesel, originally intended his machines to be powered by renewable resources: The first diesel engine, built in 1893, was fueled with peanut oil. “The use of vegetable oils for engine fuels may seem insignificant today,” he argued, “but such oils may become, in the course of time, as important as petroleum and the coal-tar products of the present time." Indeed, bio-based diesel fuel enjoyed fairly widespread use until after World War II, when cheap and stable oil supplies made petroleum diesel the more popular fuel. Concern for the environment, as well as higher petroleum prices, renewed interest in biodiesel in the 1970s, particularly after the 1973 oil crisis. In the early 1990s, soy industry trade groups began researching new uses for surplus soybean oil, including biodiesel, and sponsored university-based studies on its viability as a fuel. As the body of hard data on biodiesel has grown, so too has the biodiesel homebrew movement, encouraged by countless online biodiesel forums and communities.

Context

Many of its supporters view biodiesel as the catch-all solution to the world’s fuel supply conundrums: A large-scale switch to biodiesel would require no changes to the fueling infrastructure – biodiesel can be transported, stored, pumped just like regular diesel. To produce enough fuel to power the United States’ current needs, however, would require more feedstock cropland than is available, and growing commercial crops, of course, requires a chain of energy use that conceivably outweighs any savings: in deploying petroleum-based fertilizers, in harvesting and maintaining crops, in irrigation, etc. Recently, the use of algae found at sewage treatment plants has been researched as a possible source of biodiesel feedstock. Many algae are largely made up of biodiesel-ready lipids and grow much more quickly than earth-based crops.

External Links:

Wikipedia - Biodiesel

National Biodiesel Board

Biodiesel America

Willie Nelson’s Biodiesel

Biodiesel Now

Further Reading:

Biodiesel: Growing A New Energy Economy, by Greg Pahl

From the Fryer to the Fuel Tank: The Complete Guide to Using Vegetable Oil as an Alternative Fuel, by Joshua Tickell, Kaia Tickell, and Kaia Roman