is that bio in your tank or are you just...

So you think you can brew?

Your local fuel testing lab might disagree with you. Folks who have been on the biodiesel scene for years are making an important distinction these days: between "homebrew" and "biodiesel."

Engine problems resulting from poor fuel quality can be closely connected with a concept that got many of us into biodiesel in the first place. To wit: "It's easy to make biodiesel."

But are we really making biodiesel?

To some, shaking up fryer oil, methanol and lye in a jar makes biodiesel. After half an hour, everyone in the "How to Make Biodiesel" workshop holds up a nice 80/20 separation.

"SEE? You just drain this dark glycerine layer from the bottom and you can pour the rest right into your fuel tank!" exclaims the instructor. "That's biodiesel!"

Even brewers with "fumeless" reactors, water-wash systems and dryer tanks have only begun to acknowledge the need for quality testing. Turnkey biodiesel processing systems from online distributors often arrive with little more quality control instructions other than "you should be able to read a newspaper through it."

The resulting fuel can have total glycerine levels of double and triple the ASTM maximums (0.24%), loads of extra soaps and acid numbers that will make short work of even brand new fuel injection pumps.

Sufficient fuel quality testing is now well within the reach of the homebrewer. The 27/3 test, for example, is a brilliantly simple and fast way to gain confidence in your glyceride content. Hydrochloric acid titration is an effective way to measure soaps. The pHLip test uses chemistry magic to give accurate quality readings on several aspects of your sample for about the cost of a cup of mochaccino. Off-site fuel testing services like Utah Biodiesel Supply's will let you pay for just the ASTM tests that are relevant for a homebrewer.

Mechanics are ready to scapegoat biodiesel as soon as a check engine light flickers on. It is up to us brewers to maintain our own credibility. Next time you're filling someone's fuel tank with "biodiesel," just ask yourself: "Can I stand behind this batch?"

Editor's Note: Adopt your congressperson or senator! Subscribe a politician who should love biodiesel: just $10 in 2008.