Conventional biorefineries

This chapter surveys different process options to convert terpenes, plant oils, carbohydrates and lignocellulosic materials into valuable chemicals and polymers. Three different strategies of conversion processes integrated in a biorefinery scheme are proposed from biomass to bioproducts via degraded molecules , from platform molecules to bioproducts , and from biomass to bioproducts via new synthesis routes . Selected examples representative of the three options are given. Attention is focused on conversions based on one-pot reactions involving one or several catalytic steps that could be used to replace conventional synthetic routes developed for hydrocarbons. 

Development of a Biorefinery Fact Sheet to document and report facts and figures of biorefmeries in a common and compact format, consisting of a brief description, the classification scheme, mass and energy balance as well as a whole value chain-based sustainability assessment in comparison to conventional systems. ... 

Technological implementation status conventional and advanced biorefineries first, second, and third generation biorefineries. 

Conventional biorefineries Starch (corn, wheat, cassava) and sugar crops (sugarcane, sugar beet), wood Pretreatment, chemical and enzymatic hydrolysis, catalysis, fermentation, fractionation, separation Commercial Sugar, starch, oil, dietary fibers, pulp and paper... 

The University ofWaterloo continued the development in greater detail and showed from an economic evaluation that the process is an interesting alternative for the conventional production of ethanol. " In 1999, they compared the cost of producing ethanol from ceUulosic biomass via the hybrid thermochemical biorefinery approach, to acid hydrolysis and enzymatic hydrolysis technologies. The results indicate that the production cost of ethanol via the fast pyrolysis-based concept is competitive with the production cost via the conventional approaches. 

The need to address the issue of global warming and fossil resource depletion has prompted research on the sustainable production of environmentally benign fuels and chemicals [ 1]. A biorefinery, which utilizes biomass as the starting material for the production of fuels and chemicals, can not only generate sustainable energy but also reduce CO2 emitted by fossil fuel combustion. For instance, bioethanol is one of the most promising alternatives to conventional petroleum-based transport fuels. The United States produced 52.6 billion liters of ethanol fuel in 2011, an increase from 49.2 billion liters in 2010 [2]. 

The conventional raw materials used in chemical process are derived predominantly from fossil fuels. Alternate raw materials such as biomass can be employed to promote greener processing. In this direction, the concept of biorefineries is quite relevant [27]. The future biorefineries can employ operations such as extractive distillation with ionic liquids and hyper-branched polymers. 

Yuan, Z., Chen, B., Gani, R., (2013). Applications of process synthesis Moving from conventional chemical processes towards biorefinery processes. Computers Chemical Engineering, 49, 217-229. 

Conventionally, woody trees were broadly classified as softwood or gymnosperm and hardwood or angiosperm. Hardwood comes from angiosperms, such as oak, eucalyptus, and alder, which are dicots (Octave and Thomas, 2009). Softwood usually comes from evergreen conifer trees like pine or spruce. Other classifications of forest-based plants are broad-leaved trees and pine-leaved trees. Almost 46% of biorefinery prefers raw materials from conifer species, mainly spruce, pine, etc., and 31% of broad-leaves such as eucalyptus. Mostly stem wood is preferred as a suitable feedstock for the biorefinery process. Approximately 8% of the known biorefinery processes utilize all parts of the tree (Fitzpatrick et al., 2010). Thus the consensus in the biorefinery industry is that the feedstock selection should be based on the main constituents of the wood (cellulose, hemicellulose, and lignin) and not on specific chemicals (glucose, xylose, etc.) generally considered in conventional fermentation processes. 

If biorefinery is to be successful, then the following remedial measures need to be followed (1) proper land use policy restrict the overexploitation of resources, (2) a sustainability model has to be followed and not tiie business as usual approach, and (3) feedstock has to be obtained from planted biomass and not from conventional forests. Moreover, only degraded or barren land has to be chosen for the plantation and not the forest area. These measures can minimize the pressure on forest lands for feedstock requirements, and forests can be well utilized as a potential sink for emitted CO2. 

Recognizing the efficiencies of the petroleum refinery in producing a large variety of products simultaneously, conventional thought is that the most effective plan for conversion of bioresources will be through a biorefinery process. In the petrorefinery process based on a build-up approach, feedstocks such as crude oil... 

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