Biofuels maker Codexis Inc. has filed for a $100 million initial public offering on Nasdaq.

This blog post from the Wall Street Journal says the San Francisco-based company develops microbes that turn plants into sugars for ethanol and biodiesel production. Shell has a 20 percent stake in Codexis, a company that tried an IPO back in September 2008, but had to back off when the market crashed:

Will Codexis timing be any better this time around? There are still plenty of potholes.

The beauty of an IPO filing is that the company must file all sorts of risk factors laying out exactly what can go wrong. And in the biofuels business, that’s quite a lengthy list. Codexis (and its lawyers) cite: its sugar daddy Shell could decide it wants to stop bankrolling R&D efforts; “the development of technology for converting sugar derived from non-food renewable biomass sources into a commercially viable biofuel is still in its early stages, and we do not know whether this can be done commercially or at all”; “there are no commercial scale cellulosic biofuel production plants in operation. There can be no assurance that anyone will be able or willing to develop and operate biofuel production plants at commercial scale or that any biofuel facilities can be profitable”; new infrastructure is needed, such as rail lines; tax credits and other government subsidies could disappear; falling oil prices will pole axe revenue; fears of genetic engineering could pinch the company; and there might not be enough feedstock to turn into biofuels.

So is it time to get your Codexis stock now? Well, it all depends on your comfort level with risk. After all, it is a company headquartered on San Francisco’s earthquake zones.