by Bradley Wilson

Created on: July 30, 2009   Last Updated: August 02, 2009

Whether you grew up on a farm or in the city, at one time or another we've all had an up close and personal experience with diesel. Providing economical, reliable power delivery, diesel has powered much of the freedom of movement common to daily living. The main complaint for most people has been noise and smelly exhaust.

All internal combustion engines take in fuel and air and burn it to perform work for us. Whether burning gasoline, diesel or even wood in your fireplace, a byproduct of the combustion is burned gases. Depending on the method of burning and the fuel used, these gases can be toxic. The familiar black smoke from diesel engines is called particulate matter (PM). Both the EPA and the state of California have identified diesel particulate matter as toxic.

Originally designed to operate on peanut oil or coal dust, the simple diesel engine design uses heat and pressure to burn fuel rather than spark ignition of gasoline engines. The simplicity and flexibility of the engine make it popular among heavy industry, transport and agricultural industries. Combined with low fuel oil prices of the early twentieth century, petroleum diesel became the fuel of choice, especially for non-consumer applications. Though petroleum has been preferred, diesels have always had the capacity to operate on alternative fuel.

Fuel prices have been the driving factor for petroleum diesel dominance, until now. Biodiesel is fuel which has been produced from a renewable resource. Among the benefits of biodiesel are the biodegradable characteristic making spills less of a concern, greater fuel ignitability and higher oxygen content. Biodiesel also reduces greenhouse gas (GHG) emissions in a couple of ways - 1) less carbon dioxide is produced through burning and 2) the plants grown to make the fuel absorb the carbon dioxide that is produced. Compared to regular diesel, unblended biodiesel (B100) offers a 75% reduction in CO2, blended biodiesel - 20% by volume (B20) offers a 15% reduction in CO2 according to a Department of Energy study. Biodiesel also is more "big picture" energy balance friendly generating more energy in use than is required for its production. Varieties of biodiesel made from soy, canola or animal fat have slightly different emissions characteristics. All of which out perform petroleum diesel.

Emissions are usually tested in one of three ways: an engine dynamometer, a chassis dynamometer, or through a portable system which is carried on board a vehicle.

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