Former Imperium Renewables Inc. chairman and CEO (and prolific blogger) Martin Tobias has been Web-silent since announcing early Friday afternoon that he was hawking some NBA Seattle Supersonics tickets on StubHub. That was just before Imperium not-so-subtly dropped the news late in the afternoon of the week before Christmas that Tobias would be replaced as chairman by longtime venture investor Nancy Floyd of Nth Power and that founder John Plaza would regain the CEO spot at the heavily-funded biodiesel developer.

Tobias has been a high-profile advocate for Imperium, and for biodiesel and the alternative energy sector in general, since buying a large stake in the former Seattle Biodiesel and spearheading efforts to raise more than $200 million as Imperium worked to develop refineries. The company opened a 100 million gallon plant in Gray's Harbor, Wash., in August, and it is scheduled to build four more in Hawaii, Australia and other deep water port locations to take advantage of fungible feedstock markets.

No word yet on the reason for Tobias' departure. But  investors might not have been too happy with his statements last month to BusinessWeek that Imperium might consider going into the algae farming business itself to ensure a supply of the crop as a feedstock. The story noted that Imperium has been an enthusiastic buyer of the aquatic produce, and the company's plant manager told me a year ago that he expects it to become the dominant biodiesel feedstock over the next decade.But Imperium also has been through some very public efforts to line up other sources of oil, including a failed effort to stake Washington oil seed farmers, so it may not have been a great idea to stoke further doubts about the company's sourcing efforts as it moves toward a planned IPO. - Clifford Carlsen

See Martin Tobias' personal blog

See Dec. 22 story from The Seattle Times