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Next Generation of Agro-Industrial Lignocellulosic Residues to Eco-Friendly Biobutanol
Published in Maniruzzaman A. Aziz, Khairul Anuar Kassim, Wan Azelee Wan Abu Bakar, Aminaton Marto, Syed Anuar Faua’ad Syed Muhammad, Fossil Free Fuels, 2019
Nurhamieza Md. Huzir, Maniruzzaman A. Aziz, Shahrul Ismail, Bawadi Abdullah, Nik Azmi Nik Mahmood, Noor Azrimi Umor, Syed Anuar Faua’ad Syed Muhammad
Twenty percent of the global supply of sugar is derived from sugar beet (Beta vulgaris), while the remainder is dominated by sugarcane. In 2016, the world’s leading producer of sugar beet crop is the European Union (EU), constituting 50% of the global production of sugar beet, which is as much as 111.7 million tons [66]. From the manufacturing of sugar beet, valuable by-products that can be used as a source of energy are sugar beet pulp and sugar beet molasses. Sugar beet pulp is highly recommended for use as a feedstock since sugar beet can be harvested daily throughout the year and the pulps contain low lignin, making it suitable for use in the biofuel industry [67]. The use of acid-pretreated sugar beet pulp for biobutanol production shows higher results with an increment of solid loading. For 5%, 7.5% and 10% solid loading, the biobutanol obtained in the fermentation broth are 4.5 g/L, 6.6 g/L and 7.8 g/L, respectively [68]. Meanwhile, Clostridium acetobutylicum 2N used to ferment sugar beet molasses within 48 hours produced 14.15 g/L biobutanol titer, which is higher than the 13.2 g/L biobutanol produced after a 60-hour fermentation of glucose medium [69,70].
Challenges in Developing Sustainable Fermentable Substrate for Bioethanol Production
Published in Ayerim Y. Hernández Almanza, Nagamani Balagurusamy, Héctor Ruiz Leza, Cristóbal N. Aguilar, Bioethanol, 2023
The sugar industry promotes solutions aiming at higher yield and no waste process for ethanol production from sugar beet as well as from intermediates and byproducts like molasses. Another byproduct of the industry, i.e., sugar beet pulp (SBP), is a potential feedstock for biofuels. It contains 20–25% cellulose, 25–36% hemicellulose, 20–25% pectin, 10–15% protein, and 1–2% lignin content on a dry weight basis [55, 57].
The energy transition
Published in Arjen Y. Hoekstra, The Water Footprint of Modern Consumer Society, 2019
Only a few studies have been carried out regarding the water footprint of next-generation biofuels. Getting good estimates is hampered by the fact that most techniques are all still in a developmental stage, so that efficiencies still improve. The focus in the development is clearly on economic optimization, not on considering the intensity of natural resources use. The most comprehensive study on the water use for next-generation biofuels available to date is our study on the water footprints of biofuels from ten crop residue types (sugar beet pulp, sugar cane bagasse, cassava stalks, rice straw, wheat straw, cotton stalks, soya bean straw, rape straw, corn stover and sunflower straw) and three other second-generation bioenergy feedstocks (miscanthus, eucalyptus and pine) (Mathioudakis et al., 2017). We looked at different techniques that result in different forms of bioenergy: combustion to get heat and electricity, gasification to get syngas (which again can be used to produce heat and electricity), pyrolysis to obtain pyrolysis oil and fermentation to get bioethanol. For all feedstocks, the water footprints of heat from combustion or gasification are a bit similar. The water footprint of electricity by combustion ranges from 33 to 324 litres/MJ and the water footprint of electricity by gasification from 21 to 104 litres/MJ. We found that biofuels from crop residues have smaller water footprints than biofuels from miscanthus and wood. As for pyrolysis oil, the oil obtained from sugar beet pulp, sugar cane bagasse and cassava stalks has the smallest water footprint (7 to 8 litres/MJ). As for bioethanol, the ethanol from sugar beet pulp has the smallest footprint (6 litres/MJ). For all feedstocks, with sugar beet pulp as an exception, the water footprint per unit of energy is smaller for oil when following the pyrolysis pathway than for bioethanol when following the fermentation pathway. Biofuels from pine and eucalyptus have relatively large water footprints: 110 litres/MJ for pyrolysis oil from eucalyptus, 160 litres/MJ from ethanol from eucalyptus, 210 litres/MJ for pyrolysis oil from pine, 490 litres/MJ from ethanol from pine. Miscanthus, often mentioned as a feedstock for the biofuel of the future, has a relatively large water footprint as well: 63 litres/MJ for pyrolysis oil, 81 litres/MJ for ethanol. Note that all above figures refer to water use per unit of gross energy produced, not accounting for the energy use in the production chain. Water footprints per unit of net energy produced will thus be substantially larger.
Recovery of unburned carbonaceous matter (UCM) from sugar mill bottom ash
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Diler Katircioglu-Bayel, Hüseyin Serencam, Metin Uçurum
Beet harvesting equipment and transportation methods are well established, and delivery of the sugar beet to the sugar processing plant and follows the existing processes for the production of sugar. Pretreatment: Washing and slicing of the sugar-beets into cosettes are the initial operations. Extraction: The sugar is extracted by counter-current action from beet cosettes to obtain raw juice and beet pulp. The raw juice is thermally unstable at temperatures above 85°C. The beet pulp can be used for cattle feed or can be modified to obtain fibers for human feed. Beet Juice Purification: Milk of lime and CO2 are used for the juice purification. Coke and limestone are used for the production of CaO and CO2. The lime usage of the conventional process is about 2% beet. Classical juice purification consists of liming, carbonation, sludge separation and sulphitation. However, this process removes only a part of non-sugars from the sugar juice (proteins, pectins, inorganic salts and coloring substances). Beet Juice Concentration: By multi-effect evaporation, the thin juice with a dry substance content of 14–16% is concentrated to thick juice with 60–75% of dry matter. Crystallization: Further evaporation of water leads to crystallize and growth of crystals. Sugar crystals are separated by centrifugation from the syrup. The molasses are the by-product from which the crystallization is not possible (Řezbováetal, 2015). Sugar mills must meet their own energy requirements because of their large energy consumption. Therefore, they should not take electricity from the city network. In the beet factory, the energy requirements for processing 6000 tons of beets per day are met by 940 tons of coal and 15 tons of fuel oil (Kilicaslan et al. 1999).