Biodiesel emissions

I was recently asked about how biodiesel does on reducing emissions. While my interests is more on alternatives to petroleum I looked into it. I have found the following ;

From Encarta;
In 1997 the Veggie Van, a small motor home powered by a diesel motor that runs on a fuel made from used and new vegetable oil (called biodiesel), took a 16,000 km (10,000 mi) journey. The Veggie Van reached speeds up to 105 km/h (65 mph) and achieved a gas mileage of 10.5 km per liter (25 mi per gallon). Some fuel for the Veggie Van was made from used restaurant fryer oil, and its exhaust smelled like french fries.
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This from an article by the Albany Democrat-Herald
Biodiesel, made from barley, soy and other crops, as well as waste grease from food service or processing industries, is a renewable energy source produced domestically. Carbon dioxide and monoxide emissions are substantially reduced in vehicles that use biodiesel blends, and biodiesel’s higher lubricity helps engines run more smoothly.

Biodiesel cost varies widely, but prices can be as much as 30 cents more per gallon than highway diesel. Moreover, the Water Bureau’s research led to the discovery of several potential headaches.

Heavy vehicles that run on biodiesel can experience up to a 10 percent power reduction due to the lower Btu fuel. And the fuel has difficulty performing at low temperatures, so some vehicles would not be able to run on biodiesel in the winter.

“Biodiesel isn’t the be-all, end-all solution,’’ said Don Holmes, sustainability coordinator for the Water Bureau.