The world of soy biodiesel is suffering with nearly a third of the plants in the U.S. idled this past year. That's not what anyone wants to hear, but hopefully that's not a longer-term problem. “We're just going through a challenging time right now,” says Joe Jobe, CEO of the National Biodiesel Board (NBB).

Still, enthusiasm for biodiesel hasn't dampened — at all — if you gauge the interest by what happened at last month's NBB meeting.

Although attendance was down from the previous year, there were still more than 2,000 eager attendees who live, breathe and talk endlessly about biodiesel. At one point, I almost thought I was at an old-fashioned tent revival. A guy sitting next to me at the general session must have thought he was at a football game the way he cheered speakers on during their presentations.

ACTRESS DARYL HANNAH helped whip up the crowd, too, by once again throwing her support behind biodiesel. She even showed off her old El Camino that she's converted to biodiesel and still drives.

But the most impressive part of this four-day conference was the session on growing algae as a feedstock for biodiesel. The room for that session was packed with inquisitive people listening and firing questions at the panel about algae's viability.

Last year at this meeting there was some interest in algae and even an exhibitor showed up from India where they're already producing biodiesel from algae. But this year, there's been a tremendous ramp-up in momentum.

Jonathan Wolfson from Solazyme, which has been growing algae since 2004, says algae are “incredibly efficient lipid producers with cells that are 75% oil. With algae we're also seeing 80% fewer greenhouse gases compared to ultra-low-sulfur diesel.”

SOLAZYME HAS PRODUCED biodiesel from algae that has already met national ASTM specs and they've even tested it in jet fuel. “We're working on different strains of algae for different kinds of fuel…jets, trucks, etc.,” Wolfson says. But he admits they're at least 24-36 months away from commercializing it as fuel.

Besides recycled cooking oils and animal fats, there are other feedstocks knocking at the biodiesel door, too, such as canola, corn, sunflower, jatropha, camelina and castor. In the end, nothing comes close to soy-based biodiesel, which accounts for 65% of all the biodiesel being produced in the U.S.

For now, soy-based biodiesel reigns king. The big question: How long before it's dethroned by other feedstocks? I sure hope we've got a long wait.