Linda Benedict | 3/2/2007 11:02:29 PM
Because the sugarcane industry is a major contributor to Louisiana’s rural economy, the effect of a new, vibrant production sector would have considerable effect because it also affects the supporting industries of equipment and process plant suppliers and providers of other goods and services. An increase of just 10 percent in cane production would enhance the state’s economy by an estimated $100 million more a year.
Energy Department Funding
More than $4 million in grants from the U.S. Department of Energy over the past three years has enabled Audubon to mount a serious research effort. These grants have been in collaboration with MBI International, a nonprofit spin-off of Michigan State University. Ethanol can be produced from sugarcane biomass in two ways, which are both being investigated at Audubon:
Many claims have been made of how value-added products can be produced from sugarcane biomass. Apart from the production of paper from bagasse and generation of electricity using bagasse as a fuel in boilers, few of these are economically viable. The challenge is to find those processes, which, when incorporated into a biorefinery, will lead to products that justify the capital investment. It is anticipated that the capital required could be large, and economies of scale obtained through highvolume processing would be needed.
Many different schemes have been devised in the laboratory. The approach at Audubon has been to move from the laboratory to pilot-plant scale. This enables us to obtain data that can be used to generate design data, bringing commercial realization one step closer. Active research and recent technological improvements are likely to make commercialization possible.
Thus far, major efforts have been directed toward treating bagasse and CLM, recovering of phenols from the lignin fraction of the biomass, optimizing the enzymatic hydrolysis for different treatments and addressing the challenges of fermenting both glucose and pentose sugars into ethanol and other products. Additional work has been done on producing more cellobiose (a type of sugar that is produced from the partial hydrolysis of cellulose) for the production of added-value chemicals. Gasification research is at an early stage, but progress will be boosted with additional research help. A smaller program for producing biodiesel in a modified process using bio-ethanol rather than methanol is also under way.
What the Future Holds
A raw sugar mill already has the infrastructure in place for collecting and processing sugarcane biomass. This is a major advantage over other lignocellulosic processing options using corn stover or forest wastes. Selected add-on options, depending on the economics of individual processes, provide the route for converting a sugar mill into a biorefinery.
The economics of a biorefinery are likely to be improved by economies of scale. For instance, combining surplus bagasse and CLM from four mills in the Teche area of Louisiana can supply a plant that can process 2,000 tons of biomass dry matter per day. Augmented with molasses, this will result in a plant capable of producing about 70 million gallons of ethanol per year – a viable size for an ethanol plant. At the present average crop size of 14 million tons of sugarcane per year, the potential for ethanol production from bagasse and CLM in Louisiana is about 250 million gallons per year. This is after allowing for the use of some of the bagasse in the boilers for the generation of steam and power.
Assuming that production of ethanol from biomass becomes a commercial reality, the biorefinery potential can be greatly enhanced by processing high-biomass cane or “energy cane.” Such cane bred for biomass rather than sucrose yield can substantially improve biorefinery output. Further augmentation with sweet sorghum and perhaps the perennial grass miscanthus could make the biorefinery even more attractive and enhance the agricultural opportunities in Louisiana.
Making a sugarcane biorefinery a reality is still a few years away. But the potential rewards to Louisiana and the nation are tremendous.
(This article was published in the winter 2007 issue of Louisiana Agriculture.)