Refineries, biorefineries

A biorefinery is a facility that integrates biomass conversion processes and eqtrip-ment to produce fuels, power, and value-added chemicals from biomass. Biorefinery is the co-production of a spectram of bio-based products and energy from biomass. The biorefinery concept is analogous to today s crude oil refinery. Biorefinery is a relatively new term referring to the conversion of biomass feedstock into a host of valuable chemicals and energy with minimal waste and emissions. 

Table 1.2 Comparison of refineries and biorefineries regarding to feedstocks, building block composition, processes, and chemical intermediates produced at commercial scale Refinery Biorefinery...

To compete with the traditional fossil-based refineries, biorefineries have to exploit optimally raw materials firom plants and create multiple value chains. Therefore, the concept of a whole-plant biorefinery appears as a more convenient model. Despite the diversity of oil crops, such as soy, rapeseed, sunflower, and palm, the whole-plant biorefinery concept can be applied similarly to all of them. Differences can emerge due to the nature of the plant and the way to recover its seeds containing the vegetable oil. Palm trees, for instance, remain in the soil, and their fruits are harvested, where plants such as rapeseed or sunflower are cut every year. In both cases, the first step of the biorefinery process is to separate the oil-rich seeds firom the lignocellulosic fraction of the plant. 

The biorefinery industry is marked with a feedstock related to the dispersed nature of its diet. The incoming raw material to a biorefinery is produced in a small scale (compared to an oil refinery), and in remote, distributed locations. Consequently, the biorefinery capacity is a parameter difficult to define due to the uncertainty in collection and blending of the feedstock. The next question is to what extent will the oil industry be involved in such operations and how will that affect the fossil to renewable ratio or the intake feedstock. 

The valorization of by-products in biomass conversion is a key factor for introducing a biomass based energy and chemistry. There is the need to develop new (catalytic) solutions for the utilization of plant and biomass fractions that are residual after the production of bioethanol and other biofuels or production chains. Valorization, retreatment or disposal of co-products and wastes from a biorefinery is also an important consideration in the overall bioreftnery system, because, for example, the production of waste water will be much larger than in oil-based refineries. A typical oil-based refinery treats about 25 000 t d-1 and produces about 15 000 t d 1 of waste water. The relative amount of waste water may increase by a factor 10 or more, depending on the type of feed and production, in a biorefinery. Evidently, new solutions are needed, including improved catalytic methods to eliminate some of the toxic chemicals present in the waste water (e.g., phenols). 

Biorefinery includes fractionation for separation of primary refinery products. The fractionation refers to the conversion of wood into its constituent components (cellulose, hemicelluloses and lignin). Processes include steam explosion, aqueous separation and hot water systems. Commercial products of biomass fractionation include levulinic acid, xylitol and alcohols. Figure 3.3 shows the fractionation of wood and chemicals from wood. 

There are four main biorefineries biosyngas-based refinery, pyrolysis-based refinery, hydrothermal upgrading-based refinery, and fermentation-based refinery. Biosyngas is a mrrltifimctional intermediate for the production of materials, chemicals, transportation fuels, power and/or heat from biomass. Figrrre 3.4 shows the gasification-based thermochemical biorefinery. 

The concept biorefinery is discussed in the US National Research Council Report Biobased Industrial Products [4] and by Lynd et al. [7] in much detail. The basic idea is the processing of multiple renewable resources and the production of multiple products in a production complex. Another characteristic of biorefinery is the integration of thermal, chemical, biological and/or cataly-tical processes for an efficient and optimal processing and utilization of the raw materials. Technological, ecological and economic analysis and system design should be implemented to ensure an overall optimization of raw material conversion and product formation in a similar way as for oil refineries. 

Biorefinery A refinery that produces fuels from biomass. These fuels may include bioethanol (produced from com or other plant matter) or biodiesel (produced from plant or animal matter). 

Similarly to oil-based refineries, where many energy and chemical products are produced from crude oil, biorefineries will produce many different industrial products from biomass. These will include low-value, high-volume products, such as transportation fuels (e.g. biodiesel, bioethanol), commodity chemicals, as well as materials, and high-value, low-volume products or speciality chemicals, such as cosmetics or nutraceuticals. Energy is the driver for developments in this area, but as biorefineries become more and more sophisticated with time, other products will be developed. In some types of biorefinery, food and feed production may well also be incorporated. 

For the last 70 years or so the chemical industry has been based on crude oil (petroleum) and natural gas as basic raw materials, hence the name petrochemicals. This may not be so for much longer, however. The chemical industry is currently on the brink of a new revolution, based on the switch from fossil resources to renewable agriculture-based raw materials. From a distance the production facility of Cargill in Blair, Nebraska looks very much like a small oil refinery or medium-sized petrochemicals plant. However, closer inspection reveals that it is a corn-processing plant a biorefinery producing, inter alia, high-fruc-tose corn syrup, ethanol and lactic acid. As James R. Stoppert, a senior executive of Cargill pointed out, the chemical industry is based on carbon and it does not matter if the carbon was fixed 2 million years ago or 6 months ago [1]. 

Biorefineries are among the key areas for a successful industrial application of renewable resources. In concept, biorefineries are similar to petroleum refineries however, biorefineries use renewables instead of petroleum to produce transportation fuels and chemicals. Biorefineries can employ various combinations of feedstocks and conversion technologies to produce a variety of products. The renewable feedstocks can be of various kinds of grain, energy crops such as corn, switchgrass, miscanthus, willow, and poplar, and agricultural, forest, and industrial residues... 

Successful integration of carbohydrate chemistry in a biorefinery will greatly depend on the availability and price of the lignoceUulosic feedstock and its fractionation cost. Since the collection of biomass is Umited by its volume and density, biorefineries are likely to be smaller and more highly distributed than petroleum refineries. In order to produce meaningful volumes of products, a biorefinery should focus on a specific set of platform chemicals rather than attempting to provide an extended portfolio of products. There are two technological obstacles to the delivery of such a biorefinery, and effort is required to overcome them. First, the... 

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