What gives at Aurora Biofuels?

Robert Walsh, a former Shell exec with extensive experience in the oil industry, has resigned as CEO of the algae company "for personal reasons." Meanwhile, CFO Joe Geesman has retired. Geesman's replacement has already been installed, but a search is still underway for Walsh's replacement.

The departure of Walsh won't likely be seen in the algae industry as a sign that the company is maturing and needs a CEO to scale up the business. Walsh was that guy: the company lured him away from biofuel rival LS9 in 2009 to helm the scale-up process. Aurora comes out of research at UC Berkeley. It has optimized a genetic pathway in a strain of algae that effectively turbocharges the growth and reproduction cycle.

Last summer, Walsh fleshed out Aurora's plans to grow the algae in open ponds, the cheapest -- but also one of the most challenging -- process that is used for growing monocultures of algae. Aurora, which has been growing algae in Olympic-sized pools in Florida, was at the time negotiating leases to build a 50-acre pond that could produce 100 gallons a day by the second quarter of 2010. If all goes well and further optimizations arise, Aurora could have a 2,000-acre pond by 2011 or 2012, he said then. Such a pond set up with Aurora's algae and equipment could produce lipids for around $1.75 a gallon, which would translate to $2-a-gallon diesel, according to Walsh's estimate at the time.

Since then, however, a few things have happened. The Department of Energy gave $20 million grants to rivals like Solazyme and Algenol in December; Aurora wasn't on the list. Meanwhile, the $1-per-gallon biodiesel subsidy lapsed, forcing most biodiesel companies to cut back. (Critics will claim that the impact of the stimulus spending and subsidies prove that the government is distorting the market. That's true to a degree: without government help, they'd all die.)

A company spokeperson could not comment on Aurora's plans, but added that the company generally remains on track.

We've looked at over 60 companies trying to produce chemicals and fuel from algae, and sources in the industry say that there are way more than 100. Aurora, which has raised more than $20 million, has generally been regarded as a top-tier company, along with Solazyme, Sapphire, Solix, and a few others. More on this story as it develops.

It's been quite a month for CEO shifts. GainSpan, DayStar Technologies, Mission Motors and Topanga Technologies all have new chiefs.