Florida grants US$ 1 million to study cellulosic ethanol from sugarcane bagasse

Earlier we pointed to a basic study on the potential for the production of cellulosic ethanol from the biomass residues of tropical biofuel crops (previous post). Currently, the easily extractable parts of these crops - sweet potatoes, cassava, palm oil, sweet sorghum, sugarcane - are converted into liquid biofuels using 'first generation' technologies. The starch, sugar and oil they yield is extracted by simple mechanical processing, after which they are distilled or transesterified into fuel. The biomass residues - stems, crushed canes, leaves, stalks, fronds, shells, press cakes - are often discarded as waste if they don't find other markets. Sometimes they are even burned in the open air, thus contributing to climate change.

However, sugar and ethanol producers have learned to use bagasse, the fibrous residue from crushed canes, as a biomass feedstock for the production of steam and power in cogeneration plants. The residues contain enough energy to power the entire processing plant, and even to sell excess electricity to the grid. This tradition - most notably found in Brazil - makes both the sustainability, the GHG-balance, and the energy balance of sugarcane ethanol quite strong (earlier post). Palm oil producers in South-East Asia have recently become interested in using a similar combination of resources, not least because fossil fuels have become expensive (earlier posts on the use of 'empty fruit bunches', the use of palm oil mill effluents for the production of biogas, and on the rising popularity in SE Asia of cogeneration using biomass waste streams in general).

The economics of ethanol and the emergence of next generation bioconversion technologies may however change this already efficient way of using the biomass. Bagasse - rich in cellulose, hemicellulose and lignin - could be used as a feedstock for the production of so-called 'cellulosic ethanol' and thus have its value upgraded. This prospect has prompted Brazilian analysts to predict that sugarcane ethanol's impressive energy balance and fuel yield could be doubled, once more, in a matter of decades (earlier post), making the viability of large scale gasoline substitution all the more likely.

Help from Florida
To make this happen, help may come from Florida, the only U.S. state where the climate is favorable for the production of a tropical crop like sugar cane. The government there has awarded research funds under its 'Renewable Energy Technologies Grant Program', with one of the awarded projects being that of the Florida International University, entitled “Assessment and Development of Pretreatment for Sugarcane Bagasse to Commercialize Cellulosic Ethanol Technology” [*.pdf], for which it received a US$990,532 grant:
biomass :: bioenergy :: biofuels :: energy :: sustainability :: sugarcane :: bagasse :: cellulose :: ethanol :: Brazil :: Florida ::

The university project will determine the technical feasibility of using Florida sugarcane waste as a feedstock for a large-scale ethanol industry in the state. The institution will try to identify a cost-effective pretreatment process to make sugarcane waste a viable feedstock for ethanol production. The proposal is a joint effort between the university and Florida Crystals Corporation.

Bagasse is quite an abundant biomass resource in Florida: over a million tons of it (dry basis) are annually produced by the state's sugar industry. Although bagasse is seen as a valuable solid biofuel, there is strong commercial interest in upgrading its value by converting it into a liquid transport fuel.

Demand for ethanol in the U.S. is driven by the President Bush's 'Advanced Energy Initiative' and the Energy Policy Act of 2005 as well as the 2006 Florida Energy Act, which seek to boost biofuel use. Tariff-free ethanol exports from Florida to the Caribbean Basin are another market incentive for ethanol production in the State.

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 project states that the key challenge to commercialization - and strongest determinant of the success of cellulosic ethanol technology - is the efficient conversion of cellulose and hemicellulose to fermentable sugars during pretreatment. The extent to which these polymers are successfully hydrolyzed defines over 50 percent 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.

To close this data gap, the project team proposes to: (1) Perform lab-scale bagasse pretreatment runs encompassing the most promising thermochemical and thermomechanical processes to determine their efficacy by quantifying released sugars and potential inhibitors and measuring enzymatic digestibility; and (2) 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 cellulosic ethanol expertise: 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.


Other bioenergy projects that received grants under the program included one by Citrus Energy LLC, “Fuel Ethanol Production from Citrus Waste Biomass” [*.pdf] ($2.5 million). This company will construct a four million gallons per year ethanol bio-refinery to use citrus waste to produce ethanol. This project will transform citrus waste, an abundant agricultural residual, into a clean, affordable and locally-produced biofuel.

One by Alico, Inc., entitled “Commercial Ethanol Production from Biomass” [*.pdf] ($2.5 million), a project aimed at use biomass products to co-produce ethanol and electricity at a savings for consumers. The facility will produce ethanol for blending with gasoline at less than one-third of the current national average retail cost of gasoline, and can deliver “green” electricity at a cost of less than a dime per kilowatt hour.

Finally, a Florida Biomass Energy Consortium, received a grant for its proposal aimed at “Using High Efficiency Biomass Gasification for Industrial Drying” [*.pdf] ($320,623). This proposal is to build and operate an integrated biomass gasification system to replace natural gas use with biogas for an industrial user. This project will define and establish both the technical and economic viability of using Florida’s biomass resources for industrial drying processes that currently use natural gas as the energy source.

Technology transfers
Even though some developing countries are investing in cellulosic ethanol research themselves, in all likeliness American and European researchers will develop viable conversion technologies first. If this is the case, institutions, governments and companies will have to decide whether to share the technologies with countries in the South. There, cellulosic ethanol production would have very positive environmental impacts, as it would increase the efficiency and energy balance of the fuels, reduce the land needed to grow feedstocks and increase the value of currently produced biofuels.

There are signs that such technology transfer agreements are likely to occur. Florida is working with Brazil on an inter-American ethanol partnership (earlier post) and Brazil in turn has offered to transfer its agronomic, scientific and biofuel expertise to African countries, where the potential is vast.

More information:
Florida Renewable Energy Technologies Grants Program
Brazzil Magazine: Brazil Offers Africa Technology to Produce Bio-Fuel - Jan. 29, 2007