The Indiana Soybean Alliance just finished their Mission:Arctic Circle winter biodiesel trip from Palmer to the Arctic Circle. The 100% Permaflo Biodiesel in their tank was rated down to -67F and drove flawlessly at -23F last week.
They use urea to fractionate the thicker saturated fatty chains from the thinned unsaturated ones. Basically this means they settle the thick stuff off.
At the backyard level we do this to some extent by avoiding creamy hydrogenated fryer oils, since they are made up of those thick saturated fatty acid chains. Another way we’ve separated the oils in our systems is to settle the jugs and use the thin top stuff for spring and fall, while leaving the creamy dregs for warmer weather. This may give us spring and fall biodiesel usable at 100% to 25F, while the summer creamy biodiesel may start to gel at 50F.
What makes the permaflo process unique is the ability to cheaply and efficiently separate the thin biodiesel to the extent that it’s usable at 100% to an amazing -67F! They estimate the added cost to the process is only 5 cents a gallon.
More info in the Fairbanks Daily News-Miner and at the New York Times Blog.
Edit: The April 4th Alaska Science column in Anchorage Daily News features this story. A well written piece, as usual.