No. Biodiesel is made from vegetable oil in a chemical process. It has a viscosity and energy content that's similar to petrodiesel. For almost all vehicles, biodiesel can directly substitute for petrodiesel without any engine modifications.

Biodiesel dramatically reduces most pollutants - especially particulates -- soot -- the most carcinogenic part of the exhaust brew -- from diesel engines. In fact, B99 exhaust contains only half as soot and carbon monoxide as regular diesel exhaust.

The entire Southwest Regional Fleet of the US Marines has been using B20 in all nontactical vehicles and generators since 2002 -- with no engine problems. On the opposite end of the spectrum, all City of Berkeley vehicles use B20. There are lots of other examples.

Pretty much, at least with blends up to B20. The Marines say if they had to do it over, they'd be sure to clean out all of their fuel tanks first - biodiesel is a good solvent, and it can dissolve residues in tanks, which can lead to filter clogging. Their fuel tanks are clean now. Berkeley used B100 for a couple of years, but problems from dirty storage tanks made them switch to B20.

D2 is the type of petrodiesel that's used in the summertime. In the winter it's mixed with D1 to improve cold weather performance. Biodiesel can be used straight, as B100 (100% biodiesel) or in any blend with any kind of petrodiesel. B20 (20% biodiesel) is a popular blend, along with B2, B5, B50, and B99. People often use the terms B99 and B100 interchangeably.

There can be, just as with D2. This is a factor that all biodiesel users should be aware of. Canola biodiesel has the best cold-weather properties of any biodiesel, while palm oil biodiesel has the worst. Although we don't necessarily recommend you try this, we have found that our canola oil B99 biodiesel works just fine as low as 14°F.

Officially, nearly all manufacturers agree that biodiesel up to B5 (5% biodiesel, 95% petrodiesel) works in all diesel engines. Unofficially, millions of miles of experience show that B99 works just fine in nearly all diesel engines. There have been reports that the Ford 6.0 L engine, for example, doesn't run well on biodiesel - a problem with the lift pump -- but most engines run better on biodiesel than on petrodiesel.

Diesel engines get better mileage than gasoline engines. Some diesel vehicle owners say they get even better mileage with biodiesel, maybe because biodiesel cleans the injectors.

OK, this isn't really frequently asked, but it should be. Only the methanol used in making biodiesel comes from fossil fuels, so typical B100 produces a little over a pound of fossil CO 2 per gallon. Petrodiesel and gasoline produce 20-22 pounds of fossil CO 2 per gallon.

Again with the engines, but it's good to be cautious about this sort of thing. The key here is to use biodiesel that meets ASTM standards - this is very important. That said, on the Internet you can read about almost any kind of vehicle that's being run on B99 or B100. Volkswagen TDIs appear to be especially popular among B100 users.

We'd be happy to. Simply making biodiesel is easy and fun, and driving on your own biodiesel is really fun. Be advised, though, that making consistently high-quality biodiesel, while still fun, isn't so easy. Once they get over the thrill of making their own, most people prefer to buy it when it's available.

We have an '81 Mercedes 240D that we use our own biodiesel in. The only thing we've done to it is to replace the fuel return hoses on the engine. Eventually we really should replace the other rubber fuel hoses -- newer engines don't use rubber hoses. We haven't had any fuel filter problems, which surprised us after all we'd read.

Energy balance is the ratio of how much energy a fuel produces compared to how much energy it takes to make the fuel. For biodiesel, the energy balance is between 3 and 4, meaning that up to four times -- 400% -- more energy is produced when it is burned than is used to make it (the extra energy comes from the sun). For ethanol, the energy balance is about 1.3, and for gasoline and petrodiesel it's between 0.7 and 0.9. (If the energy balance for fossil fuels was > 1.0, we wouldn't be running out of them.)

Not really. Food is (and will be) a more valuable crop, but oilseeds do have a place in crop rotations. A much more serious concern is the destruction of tropical rainforests to make way for palm oil plantations and soybean fields.

We're selling 100% Washington-grown biodiesel at our plant in Ellensburg: 1000 N. Prospect St., Unit 1. Here's a map!