Introduction
Ethanol produced from biomass has a significance role in the industry. It was not used in a large quantity until mid of 1970. The sudden increase in the prices of oil made the scientist to switch towards biomass ethanol production and as a result of that ethanol engines are 15% more efficient then other engines.
Characteristics of ethanol as a renewable fuel
Lead additives to gasoline were reduced through the 1980s as the amount of ethanol blended in the fuel was increased, and these additives were completely eliminated by 1991. The additions of aromatic hydrocarbons (such as benzene), which are particularly toxic, were also eliminated, and the sulfur content was reduced (in vehicles using blended fuel) or eliminated (in neat-ethanol fueled vehicles) [3]. The addition of ethanol instead of lead to gasoline has lowered the total carbon monoxide (CO), hydrocarbons and sulfur emissions significantly. Exhaust emissions associated with ethanol are less toxic than those associated with gasoline, and have lower atmospheric reactivity [4]. The use of ethanol has also reduced CO emissions drastically. Before the Brazilian Alcohol Pro-gram started, when gasoline was the only fuel in use, CO emissions were higher than 50 g/km driven; they had been reduced to less than 5.8 g/km in 1995. Lead ambient concentrations in São Paulo Metropolitan Region dropped from 1.4 μg/m 3 in 1978 to less than 0.10 μg/m 3 in 1991, according to CETESB (the Environmental Company of São Paulo State), which is far below the air quality standard of 1.5 μg/m 3.
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PRODUCTION PROCESS
FEEDSTOCKS
- Trees
- Grasses
- Agricultural Crops
- Agricultural Residues
- Animal Wastes Municipal
- Solid Waste
- Food Processing
Dry Mill Ethanol Process
In dry milling, the entire grain kernel is first ground into “meal,” then slurried with water to form a “mash”.
Enzymes are added to the mash to convert starch to sugar. The mash is cooked, then cooled and transferred to fermenters. Yeast is added and the conversion of sugar to alcohol begins. After fermentation, the resulting “beer” is separated from the remaining “stillage.” The ethanol is then distilled and dehydrated, then blended with about 2% denaturant (such as gasoline) to render it undrinkable. It is then ready for shipment. (not a new paragraph) The stillage is sent through a centrifuge that separates the solids from the solubles. These co-products eventually become distillers grains, as well as corn distillers oil. For more information co-products and current production, visit our co-products page.
Wet Mill Ethanol Process
In wet milling, the grain is first separated into its basic components through soaking
After steeping, the slurry is processed through grinders to separate the corn germ. The remaining fiber, gluten and starch components are further segregated. The gluten component (protein) is filtered and dried to produce animal feed. The remaining starch can then be fermented into ethanol, using a process similar to the dry mill process.
Ethanol from Cellulosic Biomass
This process flow diagram shows the basic steps in production of ethanol from cellulosic biomass
Note that there are a variety of options for pretreatment and other steps in the process and that several technologies combine two or all three of the hydrolysis and fermentation steps within the shaded box. Chart courtesy of the National Renewable Energy Lab.
PRODUCTION THROUGH FERMENTATION
COLLECT SAMPLE
Samples were collected manually according to the sampling plan in the plastic bags. Every time three samples were collected from the three restaurants to make one composite sample. Hence, total 48 random samples were collected to make 16 composite samples. Each sample contains 5kg of the tissue paper waste. Samples were taken in the clean plastic bags. Plastic bags were capped properly and preserved at the room temperature.
Drying and weighing of tissue papers
The drying of tissue paper waste was done at first. The tissue papers were placed in an oven at 1000C for about 40 minutes until all the moisture content was removed from the tissue papers. After drying the tissue paper waste was weighed. For this purpose the weighing balance was used. Seven different samples were prepared in which five samples with 100 g tissue paper waste. To produce ethanol from the paper waste, one sample was prepared with 100 g of paper and the other one was prepared with 50g tissue papers and 50 g papers.
Soaking in H2SO4 and hydrolysis of the samples
Next the tissue papers were soaked in H2SO4 (5 % by weight of H2SO4).
The H2SO4 was taken in the different variations i.e. 300ml, 400ml, 500ml, 600ml, 700ml, 500ml, 500ml for the tissue papers, papers and mixture of both (50g tissue papers and 50g papers) respectively. Afterwards the samples were placed in the autoclave for the hydrolysis. Acid hydrolysis was done due to its economic importance. The autoclave was maintained at 1200C for about 3 hours.
Filtration of the samples
The filtration of all the samples was done in the filtration assembly. The filtration was done twice in order to get the pure filtrate without any residue. The second time, filtration was done by the help of filter paper. Different quantity of the filtrate can be obtained from the different samples.
Neutralization of the samples filtrates
After filtration all the samples were neutralized by adding potassium hydroxide solution (KOH solution). The KOH solution was prepared by adding 40 g of potassium hydroxide in 100mill liter of distilled water. The potassium hydroxide solution was added according to the different concentration i.e. 50ml, 75ml, 100ml, 125ml, 150ml, 40ml and 25ml in all the samples respectively.
Fermentation
The fermentation of all the samples was done at the room temperature. The fermentation can be done by adding Yeast (Sacchromyces cerevisiae) in each sample. The Yeast can be added in the different concentration i.e. 2.5g, 5g, 10g, 15g, 20g, 10g and 10g respectively. The samples were placed at 300C for the fermentation for about 24hours.
Distillation
After fermentation all the samples were ready for the distillation. The distillation was done in the distillation assembly for about 8hours. The distillation can be held twice in order to optimize the production of bioethanol in the final product.
In that sample 700g of tissue papers were soaked in 3500ml H2SO4 (5% by weight of H2SO4). The amount of 400ml of KOH solution (180g KOH dissolved in 300ml distilled water) was added in order to neutralize and the amount of Yeast added was 66g for fermentation and after fermentation the sample was left for the distillation (twice).
SUBSTRATE CONCENTRATION
Growth of Clostridium thermocellum in batch cultures was studied over a broad range of cellobiose concentrations. Cultures displayed important differences in their substrate metabolism as determined by the end product yields. Bacterial growth was severely limited when the initial cellobiose concentration was 0.2 (wt/vol), was maximal at substrate concentrations between 0.5 and 2.0%, and did not occur at 5.0% cellobiose. Ethanol accumulated maximally (38.3 μmol/109 cells) in cultures with an initial cellobiose concentration of 0.8%, whereas cultures in 2.0% cellobiose accumulated only 17.3 μmol, and substrate-limited cultures (0.2% cellobiose) accumulated little, if any, ethanol beyond that initially detected (8.3 μmol/109 cells). In a medium with 0.8% cellobiose, ethanol was produced at a constant rate of approximately 1.1 μmol/109 cells per h from late-logarithmic phase (16 h) of growth well into stationary phase (44 h). When ethanol was added exogenously at levels more than twice the maximum produced by the cultures themselves (0.5% [vol/vol]), neither the extent of growth (maximum Klett units, 150) nor the amounts of ethanol produced (∼0.17%) by the culture was affected. The ratio of ethanol to acetate was highest (2.8) when cells were grown in 0.8% cellobiose and lowest (1.2) when cells were grown in 0.2% cellobiose.
Present 'status' of the ethanol program in Brazil
Presently there are 325 plants in operation crushing 425 million tons of sugarcane per year, approximately one-half being used for sugar and the other half for ethanol production. Approximately 17.8 billion liters of ethanol were produced in 2006, using 2.9 million hectares of land.
A typical plant crushes 2 million tons of sugarcane per year and produces 200 million liters of ethanol per year (1 million liters per day over 6 months, April to November) and costs approximately US$150 million. The planted area required to supply the sugarcane is typically 30,000 hectares. Most of the large plants are located in the state of São Paulo, where almost two-thirds of the ethanol is being produced. This state is located at a distance from the Ama-zonia region . Ethanol production in Brazil was initiated with a highly subsidized program. The price paid to producers in 1980 was US$700 for 1000 liters; over the intervening years, gains in technology and economies of scale have driven the cost down, reaching as low as US$200 per 1000 liters in 2004
Future perspectives of the ethanol program in Brazil
The efficiency of sugarcane-to-ethanol production can still be increased through improvements in the agricultural and industrial phases of the production process. For example, in the agricultural phase, good sugar cane yield and a high index of TRS (total recoverable sugar) are the main drivers for high yield of ethanol per unit of planted area. The increase of TRS from sugarcane has been very significant: 1.5% per year in the period 1977–2004, resulting in an increase from 95 to 140 kg/ha. Sugar extraction from sugar cane has also increased in the period 1977–2003. The average annual improvement was 0.3%
Important perspective of the present ethanol program in Brazil is the production of large amounts of electricity from the burning of bagasse with improved technologies. In the early days of the program, bagasse was burned inefficiently to produce the heat needed for the industrial part of the process (crushing fermentation and distillation) and there was a huge excess of waste bagasse.
Conclusion
The Ethanol Program in Brazil is firmly established today, and is replacing approximately 40% of the gasoline that would be otherwise be consumed in the country, at a competitive prices, using 2.9 million hectares of land. This has led to improvements in the air quality of the São Paulo metropolitan area, and reductions in greenhouse gas emissions.
References
- Review: The Brazilian biofuels industry
- José Goldemberg
- Prof. Luciano Gualberto, São Paulo, SP 05508-010, Brazil
- 2. CENBIO: Market and Policy Frameworks for a Sustainable
- Production and Trade of Biofuels: An Assessment of the Status in Principal Producing Countries. In ICTSD Report the Inter-national Centre for Trade and Sustainable Development; 2007.
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