Biorefinery renewables

To realize the concept of biorefinery, renewable resources need to be converted efficiently by biological means to several commodity chemicals. From the standpoint of the microbiologist who is responsible for the operation of this biorefinery, it is desirable to have only one microorganism in the biorefinery which is versatile enough to produce the various products. This situation is preferable to the (impossible) situation where different microorganisms are utilized simultaneously at the same production plant. 

Alternatively, an entirely new downstream process and product chain, using renewable raw materials, can be conceived (the biorefinery ). The chemistry will be more focused on that of oxohydrocarbons (particularly carbohydrates) rather than hydrocarbons. Understanding the materials chemistry of biomass and related products would need to be enhanced. However, work has already been undertaken to identify the top sugar-derived intermediates (Figure 1.9) on which down-stream chemical processing might be derived. 

Biomass is a renewable resource from which various useful chemicals and fuels can be produced. Glycerol, obtained as a co-product of the transesterification of vegetable oils to produce biodiesel, is a potential building block to be processed in biorefineries (1,2). Attention has been recently paid to the conversion of glycerol to chemicals, such as propanediols (3, 4), acrolein (5, 6), or glyceric acid (7, 8). 

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 biorefinery scheme was developed initially for carbohydrate-containing feedstocks. Large biorefineries are currently operating in the USA (e.g., Cargill at Blair, Nebraska) and in Europe (e.g., Roquette Frs. at Lestrem, France). The concept can be extended to produce chemicals from other renewable feedstocks. An integrated production of oleochemicals and biofuels can be achieved in biorefineries using vegetables oils as main feedstock to produce versatile platform mole-... 

Within the biorefinery framework several process options can be chosen to produce bioproducts from renewable feedstocks. We have identified the following three main options that will be illustrated by selected examples. 

Many improvements are still needed to make really effective use of renewable raw materials in biorefineries. Full utilization of the plants is needed instead of the current under utilization, as well as the development of processes to add value to all fractions of the plant and to valorize the by-products of other industrial... 

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. 

The integrated processing of renewable materials can lead to the generation of a wide range of products. Some examples of known and potential biorefinery products are [4] ... 

Approximately 89 million metric t of organic chemicals and lubricants, the majority of which are fossil based, are produced annually in the United States. The development of new industrial bioproducts, for production in standalone facilities or biorefineries, has the potential to reduce our dependence on imported oil and improve energy security. Advances in biotechnology are enabling the optimization of feedstock composition and agronomic characteristics and the development of new and improved fermentation organisms for conversion of biomass to new end products or intermediates. This article reviews recent biotechnology efforts to develop new industrial bioproducts and improve renewable feedstocks and key market opportunities. 

Two-platform concept biorefinery Another form of biorefinery, which has been recently defined by the National Renewable Energy Laboratory (NREL) (www.nrel.gov/biomass/biorefinery.html) is the two-platform concept biorefinery. 

Rupp-Dahlem, C., Cereal-Based Biorefinery New Initiatives With the BioHulf Programme, Renewable Resources and Biorefineries conference, York (2006). 

RFA, US Fuel Ethanol Industry Biorefineries and Production Capacity, Renewable Fuels Association, 2006, http //www.ethanolrfa.org/industry/locations/. 

Recent attempts aim at the controlled transformation of cellulose, hemicellulose, and lignin to platform molecules for a potential future biorefinery scenario. In this regard, the U.S. Department of Energy has published studies on potential future platform molecules that could be derived from renewable resources [35, 36]. Tailored transformation of biomass to these platform chemicals could serve as a starting point for biofuel production. This would allow the development of comprehensive biorefinery approaches that incorporate both the production of biofuels and chemicals. The... 

Continued development of the biorefinery concept should eventually lead to sources of renewable materials at costs competitive with those from petrochemical sources through... 

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