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Researchers to Evaluate Feasibility of Cellulosic Ethanol from Sugarcane Bagasse

23 February 2007

The State of Florida has awarded $990,532 to a joint effort between Florida International University (FIU) and Florida Crystals Corporation (FCC) to determine the technical feasibility of using Florida sugarcane bagasse as a feedstock for a large-scale cellulosic ethanol industry in the state.

The primary technical goal of the project is to identify a pretreatment process that can cost-effectively convert sugarcane bagasse to an enzymatically digestible and fermentable mix of sugars.

Bagasse is an abundant Florida biomass by-product of sugar extraction from sugarcane. Over a million tons of bagasse (dry basis) are annually produced by the Florida Sugar Industry and used as boiler fuel for steam and power cogeneration.

Bagasse can be converted to ethanol through a series of steps:

  1. Pretreatment to make cellulose digestible and dissolve hemicellulose to sugars;

  2. Enzymatic hydrolysis to break down cellulose into its constituent sugars;

  3. Fermentation of all sugars to ethanol; and

  4. Distillation of the fermentation broth to recover ethanol.

The key challenge to the successful commercialization of cellulosic ethanol technology, regardless of feedstock, is the efficient conversion of cellulose and hemicellulose to fermentable sugars during pretreatment.

The extent to which these polymers are successfully hydrolyzed defines more than 50% of the manufacturing cost of the produced ethanol. Although several pretreatment processes have been developed to date, none has been optimized for sugarcane bagasse because this feedstock, although abundant in Florida, is not as common in most of the country.

The project team will evaluate the most promising thermochemical and thermomechanical processes for bagasse pretreatement, and then scale up to pilot size the pretreatment that yielded the best lab results to confirm process scalability, generate samples for large-scale hydrolysis and fermentation work, and determine commercialization potential.

The project team’s evaluation will be based on a set of technical and financial criteria they have developed based on their collective experience with cellulosic ethanol processing:

  • High sugar yield from hemicellulose;
  • High cellulose digestibility;
  • Avoidance of side-reactions;
  • Minimal waste generation;
  • Minimal capital and operating cost; and
  • Process flexibility to accommodate additional Florida biomass species as supplements to bagasse, such as corn tops and trash, corn and sorghum stalks, and grasses.

The award was one of eight grants made by state through the Renewable Energy Technologies Grant Program established by the 2006 Florida Energy Act. The state received 74 grant applications for the program.

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February 23, 2007 in Cellulosic ethanol | Permalink | Comments (8) | TrackBack (0)

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Comments

One word:

Gasification.

Preferably through pyrolisis with sequestration of the charcoal residual:

http://ergosphere.blogspot.com/2006/11/sustainability-energy-independence-and.html

A Question -
Is it possible to convert ethanol to butanol ?
If so, what is the energy balance - i.e. is it worth it ?

Sugarcane in florida is already a hugely subsidized crop. Although putting this bagasse to "good use" is not a bad idea, it makes more sense to abandon sugarcane production entirely. Sugarcane production is detrimental to the environment.

Find a native grass for cellulosic ethanol conversion.

mahonj, it's not necessary to convert ethanol to butanol. Although I'm not sure how it'd be done, I guarantee you it'd be far more trouble than it's worth. Instead, one would simply ferment the sugars into butanol rather than ethanol. Thus, any feedstock you hear of that is being touted as a source for ethanol can theoretically be a source for butanol as well. However, because it is not a common biological process (as opposed to ethanol fermentation), it's not economically attractive ATM. People are working on making microbes that can cheaply ferment sugars into ethanol, but that research is years behind ethanol research.

The gasification idea is interesting. What's the yield of syn oil per tonne of input? I suppose the type of feedstock governs the outcome, but lets say corn husks or some similar ag residue. If we BTL'd that, how would it compare to current cellulosic ethanol approaches? It seems that the cellulosic must be better or why else would one bother with it. Thoughts?

tripp,
do a search on this site for Range Fuels. They just announced a gasification of biomass + municipal solid waste to ethanol plant for Georgia last week. Very cool stuff!

Plus MIT claims they have a MSW to ethanol process developed that will produce ethanol for $.05-.95/gallon. Go to Technologyreview.com and search ethanol.

Based on CIA factbook figures, Cuba has just over 7 million acres of arable land - much of it dedicated to sugar cane production. Additionally, it has an extensive rail network that rings the island dedicated to the transport and processing of sugar cane into exportable products.

Upon Castro’s death, Cuba could convert it's sugar production to ethanol production (with U.S. investment) using both sugar and cellulosic processes. It is but a short trip to U.S. gulf coast refineries for mixing with gasoline using cheap bulk tanker ship transportation. Tanker shipping is cheaper than trucking it from the U.S. Midwest, since ethanol cannot be sent via pipeline.

It has the added benefit of providing a good source of income to the post-Castro government while tying U.S-Cuban economies back together after the long embargo.

Hi!
I want to know more about the types of pretreatment of the sugarcane bagasse.There's the steam explosion, the alkali or acid attack, but all of them have negative consequences on the fermentation process. Wich others pretreatment types do exist?

Thanks.

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