ADM and Cargill to name just 2 companies with big bucks in grain don't want this known. Corn and soy are bad biofuels. Each are consumed by humans and other animals with subsequent supply and demand problems. Each must be planted, fertilized, cultivated, transported and processed. Ethanol gives less power per measured unit. I have read the rain forests are being destroyed to make room for soy fields. No personal experience. Corn requires extreme amounts of water to grow and process into ethanol (which personally affects me here in Missouri). The CO2 drawn from the sky as it grows-goes back in the air as it's burned. I think that would be called a zero gain at best.
Switchgrass may be better with no fertilizer, no yearly planting, minimal watering, simple cultivation, more efficient CO2 extraction and easier processing.
I think, as stated above, waste products are great. i.e. used cooking oil. This will get scares when more demands are placed.
Today, nuclear power is the cleanest with the least effect on the environment. The wastes can be reused when the economy of scale is appropriate. Think electric, efficient diesel, light weight vehicles and Hydrogen power.
Just my 2 cents. By the way.
This is from someone with a BS in Biology and an emphysis in Environmental Biology but obviously lacking in writing skills.