Protein feeds coproduction in biomass conversion to fuels and chemicals



Agriculture has changed greatly in the past in response to changing human needs. Now agriculture is being called on to provide raw materials for very large-scale fuel and chemical production. Agriculture will change again in response to this demand and all producers and users of agricultural feedstocks will be affected by this change. For example, livestock feeding practices have already changed in response to the availability of distillers' grains from corn ethanol production. A fuels industry based on herbaceous biomass energy crops will be many-fold larger than the existing corn ethanol industry and will produce its own set of impacts on livestock feeding. We explore here one of these impacts: the availability of large new sources of feed protein from biomass energy crops.

In addition to structural carbohydrates, such as cellulose and hemicellulose, herbaceous biomass energy crops can easily be produced with approximately 10% protein, called ‘leaf protein’. This leaf protein, as exemplified by alfalfa leaf protein, is superior to soybean meal (SBM) protein in its biological value. Leaf protein recovery and processing fit well into many process flow diagrams for biomass fuels. When leaf protein is properly processed to concentrate it and remove antinutritional factors, as we have learned over the years to do with soybean meal protein, protein in leaf protein concentrate (LPC) will probably be at least as valuable in livestock diets as SBM protein.

If LPC is used to meet 20% of total animal protein requirements (i.e., market penetration of 20%) then the potential utilization of leaf protein concentrate could reach as much as 24 million metric tons annually. This leaf protein will replace protein from SBM and other sources. This much leaf protein will reduce by approximately 16 million hectares the amount of land required to provide protein for livestock. Likewise the amount of land required to meet fuel needs will effectively be reduced by 8 million hectares because this land will effectively do ‘double duty’ by producing needed animal protein as well as feedstocks for fuel production. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd