Lignocellulosic Biomass Valorization for Bioethanol Production: a Circular Bioeconomy Approach (original) (raw)

State of the Art and Future Trends of Bioethanol Production

With efforts to reduce global reliance on fossil fuels and lower the greenhouse gas emission, an increasing search for renewably sourced materials, which can be used as feedstock for biofuel production, is ongoing in the past few decades. At the present, ethanol is the most common alternate fuel and is already produced on a fair scale, representing a sustainable substitute for gasoline in passenger cars. Basically, in Brazil ethanol is produced through the fermentation of sugar cane molasses. In the United States ethanol is produced by fermenting starch crops that have been converted into simple sugars, and the major feedstock for this fuel is corn. Various countries have been increasing their ethanol production as well, such as India (using sugar cane), Thailand (cassava), France (sugar beet), China (corn) and Canada (wheat), among others. Though these agricultural commodities are major issues for both food and fuel economies, they are likely to be insufficient in the near future, presenting great challenges for food processors and biofuels producers in the 21 st century. Alternatively, the conversion of cellulosic material into ethanol is relatively low up to date, compared to sugar or starch crops, leading the need to develop fermentation processes that can convert energy crops, such as grasses, and agricultural by-products, such as straw and corn stover, into bioethanol, allowing high conversion of both hexoses and the difficult to ferment pentoses into ethanol at high yields. Therefore, the search for technological breakthrough is on the high, aiming to develop technologies for effectively converting agricultural and forestry lignocellulosic residues to fermentable sugars.

Current progress on lignocellulosic bioethanol including a technological and economical perspective

Environment, development and sustainability, 2024

Growing interest in lignocellulosic bioethanol stems from the European Union's renewable energy directive, targeting a global bioethanol output of 130 billion L to achieve a minimum threshold of 42.5%. Despite industrialization challenges, recent advancements, especially in crucial stages like pretreatment, hydrolysis, and fermentation, are transforming the landscape. This review delves into the progress of bioethanol production, addressing technological, environmental, and economic hurdles. Innovations such as deep eutectic solvent pretreatment and mechanocatalysis, offering advantages like 30% and 100% solid loading, respectively, surpass traditional techniques and enzymatic hydrolysis in yielding better results. Improved pretreatment methods, enzyme exploration, saccharification techniques, genetic engineering, and integrated biorefineries contribute to overall economic viability. Ongoing research involves techno-economic analysis for costeffective strategies, aiming to enhance the competitiveness of lignocellulosic bioethanol production. Scrutinizing the feasibility of these innovative approaches not only highlights their potential to overcome existing shortcomings but also envisions a more attractive future for industrial bioethanol production. Embracing these advancements could pave the way for a vibrant and sustainable bioethanol industry.

Bioethanol from Lignocellulosic Biomass: Current Findings Determine Research Priorities

The Scientific World Journal, 2014

Second generation" bioethanol, with lignocellulose material as feedstock, is a promising alternative for first generation bioethanol. This paper provides an overview of the current status and reveals the bottlenecks that hamper its implementation. The current literature specifies a conversion of biomass to bioethanol of 30 to ∼50% only. Novel processes increase the conversion yield to about 92% of the theoretical yield. New combined processes reduce both the number of operational steps and the production of inhibitors. Recent advances in genetically engineered microorganisms are promising for higher alcohol tolerance and conversion efficiency. By combining advanced systems and by intensive additional research to eliminate current bottlenecks, second generation bioethanol could surpass the traditional first generation processes.

Second generation bioethanol production: A critical review

It is a popular fact that the world's dependency on fossil fuel has caused unfavourable effects, including lessening crude oil reserve, decreasing air quality, rising global temperature, unpredictable weather change, and so on. As the effort to promote sustainability and independency from fossil fuel, bioethanol is now favoured as the blend or fossil petrol substitute. However, the feedstock functionality of first generation bioethanol production is restricted due to its edibleness since it would clash the feeding purpose. Second generation bioethanol production fulfils the impractical gap of first generation since it employs non-edible feedstock sourced from agriculture and forestry wastes. Lignocellulosic and starchy materials in them are convertible to fermentable sugars that are able to be further processed, resulting anhydrous bioethanol as the end product. This paper critically reviews the existing variance of second generation bioethanol production methodologies, namely pre-treatment, hydrolysis, fermentation and distillation, as well as the worth of second generation production for future reference. The discussions in this paper are also fit as the fundamental for feasible planning of second generation bioethanol production plant.

Advanced Bioethanol Production: From Novel Raw Materials to Integrated Biorefineries

Processes

The production of so-called advanced bioethanol offers several advantages compared to traditional bioethanol production processes in terms of sustainability criteria. This includes, for instance, the use of nonfood crops or residual biomass as raw material and a higher potential for reducing greenhouse gas emissions. The present review focuses on the recent progress related to the production of advanced bioethanol, (i) highlighting current results from using novel biomass sources such as the organic fraction of municipal solid waste and certain industrial residues (e.g., residues from the paper, food, and beverage industries); (ii) describing new developments in pretreatment technologies for the fractionation and conversion of lignocellulosic biomass, such as the bioextrusion process or the use of novel ionic liquids; (iii) listing the use of new enzyme catalysts and microbial strains during saccharification and fermentation processes. Furthermore, the most promising biorefinery app...

Bioethanol Production from Lignocellulosic Materials -An Overview

Energy consumption has increased steadily as the world population has grown and more countries have become industrialized. The fossil fuels, such as Crude oil, Coal and natural gas have been the major resources to meet the increased energy demand. However, they are gradually being depleted to extinction because they are not renewable. Moreover, serious environmental and ecological problems have been aroused during their exploitation and use. Therefore, there is great interest in exploring alternative energy source to maintain the sustainable growth of society. Ethanol, a clean and renewable energy source, which can be produced through fermentation from renewable biomass, has drawn much attention from the government and researchers. Apart from an alternative to traditional energy sources, ethanol has been widely used as a solvent or feed stock in pharmaceutical and chemical industries. However, fermentative production of ethanol has been limited using current maize starch based technology because of raw material shortage and high cost. A potential method for low cost fermentative production of ethanol is to utilize lignocellulosic materials such as agricultural wastes. We would now discuss and cite out the rapid progress in the eld of bioethanol from lignocellulosic materials over the past few decades.

Recent Progresses in Bioethanol Production from Lignocellulosic Materials: A Review

Natural energy sources like petrol and diesel are going to be diminished in the coming future which will lead to increase in the prices and demands of fossil fuels. Therefore, it is important to find a sustainable alternate of fossil fuels. Bioethanol is one of the alternatives, which is produced from different feedstocks including sugar-based, starch-based and lignocellulose-based materials through fermentation. Since sugar-based (sugar cane and sugar beet) and starch-based (corn) materials are sources of staple food, therefore, research on lignocellulosic materials for bioethanol production is a subject of recent studies. Ethanol production from lignocellulosic materials involves different steps such as pretreatment, hydrolysis, followed by fermentation process and finally ethanol purification. In this review, we have summarized the recent progresses in bioethanol production and processing from lignocellulosic materials.

Challenges and Opportunities for Producing Bioethanol from Lignocellulosic Biomass

2008

Energy is the lifeline of global economy. Diminishing fossil fuel reserves and increased concerns over environmental pollution accelerated the need to look for renewable and environmentally sustainable energy sources. In this context, ethanol derived from biomass is advocated as a prominent contributor to offer a potential means to meet our energy needs. Being abundant and outside the human food chain makes lignocellulosic biomass, suitable and sustainable for ethanol production. Several schemes for the conversion of lignocellulosics into sugars have already been demonstrated in laboratory and pilot plant scale. The general procedure involves pretreatment of feedstock followed by hydrolysis to obtain fermentable sugars which are then converted to ethanol by fermentation. The present paper reviews the technological advancements made to date and the challenges involved in each of these processing steps. A procedure to calculate theoretical ethanol yields is also described.

Realistic approach for full-scale bioethanol production from lignocellulose: A review

Journal of Scientific and Industrial Research, 2008

This paper reviews current status of bioethanol production including substrates, fermenting microorganisms and technology for a full-scale process development. Considering main drawbacks, several parameters (high substrate loadings, sugar recovery after pretreatment, tolerance to inhibitory compounds and xylose fermentation by yeast) must be optimized for a successful industrial process for bioethanol production from lignocellulose.