The bottleneck for cellulosic bioethanol commercilization

When talking about the bottleneck of cellulosic bioethanol commercialization, the 1st pop-up issues may be the technology of pretreatment, the efficiency of enzymatic hydrolysis, C5 microorganisms, etc. Another factor may be too much politics in this area. Too much talk, less action; too many talkers, not many real workers.....