A.H. Sebayang

Bio: A.H. Sebayang is an academic researcher from University of Malaya. The author has contributed to research in topics: Biodiesel & Biofuel. The author has an hindex of 15, co-authored 32 publications receiving 1559 citations.

Second generation bioethanol production: A critical review

Abstract: 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.

Second generation bioethanol production: A critical review

Abstract: 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.

Review of Second Generation Bioethanol Production from Residual Biomass

Abstract: In the context of climate change and the depletion of fossil fuels, there is a great need for alternatives to petroleum in the transport sector. This review provides an overview of the production of second generation bioethanol, which is distinguished from the first generation and subsequent generations of biofuels by its use of lignocellulosic biomass as raw material. The structural components of the lignocellulosic biomass such as cellulose, hemicellulose and lignin, are presented along with technological unit steps including pretreatment, enzymatic hydrolysis, fermentation, distillation and dehydration. The purpose of the pretreatment step is to increase the surface area of carbohydrate available for enzymatic saccharification, while minimizing the content of inhibitors. Performing the enzymatic hydrolysis releases fermentable sugars, which are converted by microbial catalysts into ethanol. The hydrolysates obtained after the pretreatment and enzymatic hydrolysis contain a wide spectrum of sugars, predominantly glucose and xylose. Genetically engineered microorganisms are therefore needed to carry out co-fermentation. The excess of harmful inhibitors in the hydrolysate, such as weak organic acids, furan derivatives and phenol components, can be removed by detoxification before fermentation. Effective saccharification further requires using exogenous hemicellulases and cellulolytic enzymes. Conventional species of distiller's yeast are unable to ferment pentoses into ethanol, and only a very few natural microorganisms, including yeast species like Candida shehatae, Pichia (Scheffersomyces) stipitis, and Pachysolen tannophilus, metabolize xylose to ethanol. Enzymatic hydrolysis and fermentation can be performed in a number of ways: by separate saccharification and fermentation, simultaneous saccharification and fermentation or consolidated bioprocessing. Pentose-fermenting microorganisms can be obtained through genetic engineering, by introducing xylose-encoding genes into metabolism of a selected microorganism to optimize its use of xylose accumulated in the hydrolysate.

Patent landscape review on biodiesel production: Technology updates

Abstract: Biodiesel is a renewable fuel made from vegetable oils and animal fats. Compared with fossil fuels, it has the potential to alleviate environmental pressures and achieve sustainable development. In this paper, 1660 patents related to biodiesel production were reviewed. They were published between January 1999 and July 2018 and were retrieved from the Derwent Innovation patent database. The patents were grouped into five categories depending on whether they related to starting materials, pre-treatment methods, catalysts, reactors and processing methods, or testing methods. Their analysis shows that the availability of biodiesel starting materials depends on climate, geographical location, local soil conditions, and local agricultural practices. Starting materials constitute 75% of overall production costs and, therefore, it is crucial to select the best feedstock. Pre-treatment of feedstock can improve its suitability for processing and increase extraction effectiveness and oil yield. Catalysts can enhance the solubility of alcohol, leading to higher reaction rates, faster biodiesel production processes, and lower biodiesel production costs. Moreover, the apparatus and processes used strongly affect the oil yield and quality, and production cost. In order to be commercialized and marketed, biodiesel should pass either the American Society for Testing and Materials (ASTM) standards or European Standards (EN). Due to increases in environmental awareness, it is likely that the number of published patents on biodiesel production will remain stable or even increase.