Sugar cane biomass

Fermenting grains with yeast produces a grain alcohol. The process also works with other biomass feedstocks. In fermentation, the yeast decomposes carbohydrates which are starches in grains, or sugar from sugar cane juice into ethyl alcohol (ethanol) and carbon dioxide. The process breaks down complex substances into simpler ones. 

The bulkier biomass crops such as wood waste, switchgrass, miscan-thus or other cellulosic feedstocks have less sugar than corn or sugar cane, so it requires more biomass volume to yield the same quantity of ethanol that corn or sugar can produce. 

Starch and fatty acids are the main food constituents of biomass. Sugar is derived from starch by hydrolysis or directly by extraction from sugar cane or beet. Fermentation converts sugars into alcohol that can be directly used as fuel, or in principle can be used as the raw material of a bioreftnery plant for further upgrading. Triglycerides, derived from oil seeds, are used to be converted into biodiesel through transesterification processes (Fig. 1.14). 

Both in the USA and the EU, the introduction of renewable fuels standards is likely to increase considerably the consumption of bioethanol. Lignocelluloses from agricultural and forest industry residues and/or the carbohydrate fraction of municipal solid waste (MSW) will be the future source of biomass, but starch-rich sources such as corn grain (the major raw material for ethanol in USA) and sugar cane (in Brazil) are currently used. Although land devoted to fuel could reduce land available for food production, this is at present not a serious problem, but could become progressively more important with increasing use of bioethanol. For this reason, it is important to utilize other crops that could be cultivated in unused land (an important social factor to preserve rural populations) and, especially, start to use cellulose-based feedstocks and waste materials as raw material. 

Currently, ethanol is produced from sugar beets and from molasses. A typical yield is 72.5 liters of ethanol per ton of sugar cane. Modem crops yield 60 tons of sugar cane per hector of land. Production of ethanol from biomass is one way to reduce both the consumption of erode oil and environmental pollution. Domestic production and use of ethanol for fuel can decrease dependence on foreign oil, reduce trade deficits, create jobs in rural areas, reduce air pollution, and reduce global climate change carbon dioxide build-up. 

Such a country is Brazil. Burdened under a massive balance of payments deficit due mainly to a lack of any petroleum reserves, Brazilians have been looking to other fuel sources for some time. Already some Brazilian gasoline contains a substantial percentage of ethanol derived from biomass fermentation (principally sugar cane bagasse and molasses). 

At current crude oil prices, the production of ethanol from biomass is not profitable, either. Whether produced from beets, sugar cane, or com, it can become competitive only if it is subsidized. And these subsidies would only be forthcoming for political reasons to please their farmer voters, the French, Brazilian, and United States governments... 

The prices of some pertinent examples of agriculture-based raw materials (biomass) are compared with oil and coal in Table 8.1. It is obvious that the cheapest source of carbon is agricultural waste, i.e. waste plant biomass such as corn stover, wheat straw and sugar cane bagasse, which consists primarily of lig-nocellulose. 

Waldheim, L., Morris, M., Leal M.R.L.V., (2001) Biomass power generation Sugar cane bagasse and trash. In this proceedings. 

Biomass Power Generation Sugar Cane Bagasse and Trash... 

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