Aventine Renewable Energy has just taken another knock. This time, it is because Soleil Securities has downgraded Aventine Renewable Energy from Buy to Hold with a $25 price target.

This comes less than a week after Analysts at DE Research gave the company a "neutral" rating with a target price is set to $32.

There has been quite a shake-out in the ethanol sector over the last couple of months. Confidence in the sector has been tested by the Xethanol share sleuth story and some hard questions about how big an impact biofuels can make, given existing agricultural resources and rising energy demand.

It has to be said though that biofuels are still at their very beginning and whilst scaling up is going to be difficult, the external pressures that work in their favour such as high oil prices and middle eastern security concerns are not going away any time soon.