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Development of Biorefinery Systems: From Biofuel Upgrading to Multiproduct Portfolios
Published in Carlos Ariel Cardona Alzate, Jonathan Moncada Botero, Valentina Aristizábal-Marulanda, Biorefineries, 2018
Carlos Ariel Cardona Alzate, Jonathan Moncada Botero, Valentina Aristizábal-Marulanda
Biorefinery corn considers ethanol, BTX, and steam production using corn and DDGS as feedstocks [10]. Figure 7.3 indicates the flowsheet of corn biorefinery. Ethanol production is a classic “dry mill corn ethanol production”, which includes pretreatment, enzymatic hydrolysis, fermentation, ethanol purification (distillation and molecular sieves), and DDGS separation. DDGS are pretreated using drying (moisture 2% wt) and milling. These DDGS can be used for feed or for thermochemical transformations. Pretreated feedstock is subjected to a catalytic pyrolysis. The obtained product is composed of a mixture of aromatics, gases, water, and nitrogen that is conducted to a collection system (two condensers and an electrostatic precipitator) in order to collect the bio-oil (in aqueous and oil phases). Aqueous phase is treated as wastewater and the oil phase is separated in light and heavy fractions. The light fraction contains benzene, toluene, and p-xylene that are recovered as individual compounds. The heavy fraction includes aromatic compounds that are subjected to hydroprocessing to obtain hydrocarbons. The gases obtained in catalytic pyrolysis are olefins, CO, and CO2 that are separated by cryogenic separation. The stream of gases is sent to a boiler for combustion and steam is generated to supply the energy requirements of the plant [10]. Table 7.4 shows the production capacity and energy consumption of the corn biorefinery.
Hydrocarbons as Fuels and Petrochemicals: Shaping the Past, Dominating the Present, Complicating the Future
Published in Richard J. Sundberg, The Chemical Century, 2017
A 2006 study compared “energy return” for ethanol produced from corn with that produced from cellulosic biomass. Five of the six studies of corn ethanol calculated positive ratio ranging from 1.29 to 1.62, indicating 29–62% gain in energy content over energy input. Three of the four studies on cellulosic ethanol yield gave values ranging from 4.40 to 6.61, but one study showed a fractional return (0.69), indicating more energy is consumed than produced. Assuming that a “consensus” can be derived from these results, they indicate a significant (roughly 40–50%) gain in usable energy via corn fermentation and potentially much larger (400–600%) for cellulosic ethanol.3 It should be noted that on the basis of crude oil energy content, the energy return of gasoline is fractional, because of the energy needed to extract, transport, refine, and distribute it. It is the availability of existing petroleum deposits that give petroleum its economic advantage.
Innovative conversion of food waste into biofuel in integrated waste management system
Published in Critical Reviews in Environmental Science and Technology, 2022
Halimatun Saadiah Hafid, Farah Nadia Omar, Nor’Aini Abdul Rahman, Minato Wakisaka
While food-fuel concerns sparked a debate, environmental NGOs play important role in raising the sustainability credentials of biofuel impacts on water and soil. Large scale production of first generation of biofuel especially corn-ethanol should be avoided as it might develop pressure on large water and fertilizer consumption and not feasible for efficient water footprint (Holmatov et al., 2019). Meanwhile, the second generation biofuel crops using agricultural crops and woody tree species, switchgrass (Panicum virgatum) and miscanthus (Miscanthus giganteus) grass have been claimed to be more energy and water efficient as its extensive root system improves not only soil aggregation and porosity, but also water infiltration and nutrient uptake systems (Duchene et al., 2019). Switchgrass have been projected to increase evapotranspiration by 25% compared to the conventional corn cultivation (Hickman et al., 2010) while Boles (2013) used SWAT model to observe the reduction of sediment and nutrient loading at watershed by switchgrass bioenergy crop.
The greenhouse gas benefits of corn ethanol – assessing recent evidence
Published in Biofuels, 2020
Jan Lewandrowski, Jeffrey Rosenfeld, Diana Pape, Tommy Hendrickson, Kirsten Jaglo, Katrin Moffroid
A key objective of the RFS2 is to reduce greenhouse gas (GHG) emissions associated with transportation fuels. Currently, the only cost-effective biofuel substitute for gasoline is ethanol. Under the RFS2, ethanol can qualify as a conventional, advanced, or cellulosic biofuel. Conventional biofuel is defined as ethanol made from cornstarch. To be a renewable fuel, corn ethanol produced in refineries that began construction on or after 19 December 2007 must have life-cycle GHG emissions at least 20% lower than an energy-equivalent quantity of average gasoline in 2005.1 Corn ethanol produced in refineries in place or under construction on that date is grandfathered in as conventional biofuel regardless of its GHG profile. Ethanol made from cellulose, hemi-cellulose, lignin, sugar, starch (not from corn), and various types of waste biomass that has life-cycle GHG emissions at least 50% lower than those of gasoline qualify as ‘advanced biofuels’. Additionally, ethanol made from cellulose, hemi-cellulose, or lignin that has a GHG profile at least 60% lower than that of gasoline qualifies as ‘cellulosic biofuel’. Over time, advanced and cellulosic biofuels receive increasing shares of the annual renewable fuel mandate.
Virtual water: its implications on agriculture and trade
Published in Water International, 2018
Chittaranjan Ray, David McInnes, Matthew Sanderson
Pricing water is directly relevant to the economics of sustainability. It is controversial. Politicians, citizens and the agri-food sector need to confront trade-offs associated with the reliance on government subsidies to produce feed, food, fiber and fuel from agricultural crops. Subsidies may be well-intentioned but they can hide the true cost of water and encourage unsustainable agricultural practices. In Nebraska, for example, price supports and subsidies for corn have changed crop rotations as producers seek consecutive high yields. What seemed at one time like an endless bounty of groundwater, combined with relatively inexpensive energy to pump it, has created significant momentum to continuously grow the crops that show the greatest short-term profit. In the U.S., federal government subsidies, including the corn ethanol subsidy, support this practice.