JEFFERSON CITY, Mo. -- In response to lingering questions about the viability, sustainability and "greenness" of biodiesel fuel, an executive of the National Biodiesel Board insists biodiesel is the "epitome of a green fuel."

"The amount of greenhouse gases biodiesel reduced in 2007 alone was equal to taking 700,000 vehicles off the road," says Don Scott, director of sustainability of the biodiesel board. "The U.S. biodiesel industry aims to quadruple that positive effect by 2015."

According to Scott, biodiesel fuel reduces atmospheric carbon dioxide by 78 percent, compared with petroleum diesel. That reduction is proven, he says, in a study by the U.S. Department of Energy and the U.S. Department of Agriculture on soy-based biodiesel.

New and varied biodiesel feedstocks - such as the fat byproducts of meat processing and waste greases - are increasing in use, says Scott.

The majority of U.S. biodiesel is still made from surplus soybean oil. The food protein is 80 percent of a soybean - the traditional economic driver for soybean farming.

Soybean yields have been increasing but net acreage being farmed in the United States has not increased in nearly five decades.

Assertions that warn against converting land to grow biofuel crops do not reflect what is actually going on in the United States, according to Scott.

Furthermore, biodiesel has one of the highest energy balances of any liquid fuel, at 3.5-to-1, according to the USDOE and USDA. For every unit of energy it takes to make biodiesel, 3.5 units are gained.

By comparison, every unit of energy it takes to refine diesel fuel, you get 0.83 unit back. Thats a negative energy balance.

Moreover, nitrogen oxide is not raised in biodiesel - it comes out neutral.

Biodiesel production also results in 79 percent less wastewater and 96 percent less hazardous waste, compared with petroleum refining, according to Scott.

Based on rigorous data, ASTM International has approved specifications for blends of B6-B20, and for B5 in the diesel fuel specification. ASTM is a consensus organization that includes engine manufacturers and petroleum distributors.

"Biodiesel is here and can be used in modern and traditional diesel engines to improve emissions, our economy and energy independence," says Scott.