Biodiesel sure gets great press:  see here, here, here, and here for stories from the Northwest over the past few days (courtesy of Tidepool).

To recap:  biodiesel is a petroleum substitute made from plant oils or animal fats, and that generally burns more cleanly than petroleum diesel. It’s fairly easy to modify ordinary diesel vehicles so that they can run on biodiesel; you just have to replace a few hoses.  And to add to biodiesel’s cachet, much of what’s sold right now is made from recycled cooking oil, such as fryer grease, that’s collected and processed by local entrepeneurs. 

What could be better—you get the benefits of cleaner air, less petroleum, lower CO2 emissions, reduced waste, and support for local businesses, all in one tank.

But the last of the articles above, from the Humboldt, California Times-Standard, also contains hints of why we should be cautious about the prospects for biodiesel from waste oil.  The county’s main biodiesel producer, Footprint Recycling, produces about 2,500 gallons of biodiesel per month.  And the main proprietor, Andrew Cooper, estimates that they have access to about 50% of the county’s waste oil, and would like to get his hands on more.

But Humboldt county has about 130,000 residents, and if they consume gasoline at the state average, they use a total of roughly  4.4 million gallons of gasoline per month.  That means that, even if Footprint Recycling could get its hands on all of the used fryer grease in the county, the company would still supply less than 0.2% of the county’s transportation fuel needs.

This isn’t a strike against biodiesel. Far from it—I think that biodiesel from waste oil probably has an important niche in the Northwest’s energy system.  But it’s important to keep the scale of the task in mind:  as sexy as the idea may seem, we’re never going to power rush hour with restaurant grease.  And reducing petroleum consumption by more than a token amount will require much bigger and more profound changes in our lifestyles.