Cooking with Gas

Advocates of renewable energy, opponents of "oil wars," and environmentalists of all denominations had reason to cheer last week when Mayor Gavin Newsom announced that the city's 1,500 diesel vehicles had been converted to biodiesel. The mayor's press release boasted that the switch to the cleaner fuel will greatly reduce carbon monoxide and greenhouse gas emissions.

No doubt this is a good thing. But before we engage in an orgy of attaboys, you might be interested to know that the city won't be using the most enviro-friendly biofuel around.

Pure biodiesel, known as B100 or "neat" biodiesel, is the hallowed holy grail of the movement. But the city's collection of buses and other large vehicles will be chugging along on B20, a mix of four parts diesel to one part biodiesel — which is not nearly as clean (although still much better than the old-fashioned fuel).

While San Francisco officials hope to eventually implement a B100 system in the municipal infrastructure, they're taking baby steps for now. "The city would like to go to as high a percentage of biodiesel as possible, but it would have been a rougher transition to go straight to B100 in the beginning," says Eric Bowen, chair of San Francisco's Biodiesel Access Task Force. "Problems would have shown up right away if any engines were unmaintained or were still dirty with old residue. Using B20 first, one becomes familiar with the fuel's properties, and it's easy to ratchet up the percentage from there."

San Francisco's precautionary approach comes after Berkeley's own B100 program failed after just a few years. Berkeley began running a sampling of city vehicles on veggie fuel in 2001, then ramped up to 188 vehicles in 2003. Environmentalists nationwide applauded. Then, two years later, at least two large trucks stalled in busy intersections, their fuel lines clogged with impure or tainted fuel. The B100 project was cancelled and Berkeley has since installed a more modest B20 program like the one San Francisco is adopting.

Because biofuel is essentially a rich and nutritious food substance, it is highly prone to infestation by algae and fungi. This can turn the slick grease into a thick, slimy gel that may clog fuel filters, which is what happened in Berkeley. While some people blamed various parties — including several unlicensed biodiesel suppliers — for spoiling Berkeley's achievement by doling out contaminated fuel, most agree today that the B100 program failed due to systemwide inexperience in producing and transporting biodiesel.

"We've had the benefit of learning from Berkeley's problems," Bowen said. "We have lots of checks and balances to control the quality of the fuel, which Berkeley didn't have."

Another obstacle to converting to B100 is that, ironically, it would require San Francisco to import more biofuel from the Midwest via petroleum-powered trains. Currently, the city's biodiesel originates in Midwest soybean fields and is transported west by rail. Bowen says gas-powered trains are widely known to be just a shade less fuel-efficient than open ocean barges in transporting goods, although they are vastly more efficient than highway delivery.

San Francisco officials are investigating the possibility of powering Muni buses entirely with discarded cooking oil collected from the city's grease-producing restaurants. However, Bowen says, a B100 program would almost certainly require supplemental oil imports from the heartland, since San Franciscans just don't eat enough fried food.

Hear that, city dwellers? While eating greasy, artery-clogging crap may be bad for your health, it seems it could be great for the environment.