Carbon biorefineries

The biorefinery approach is the most sound in terms of truly exploiting the potential of an aquatic biomass, and this concept is now becoming accepted on a worldwide basis. In the biorefinery approach, the economic and energetic value of the biomass is maximized, although it must be emphasized that fluctuations in the prices of fossil carbon (coal, oil, gas) raises uncertainty regarding the opportunity to produce biodiesel from aquatic biomass. For example, when the oil price is below US 120 per barrel it is uneconomic to produce biodiesel in this way. On the other hand, an aquatic biomass demonstrates an excellent potential for use as a source of specialty chemicals, with some components also having added value as animal feeds or fertilizers. 

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]. 

On the other hand, the six-carbon unit of glucose is one of the most prominent components in biomasses, is easy to produce, and represents one of the most attractive building blocks for the preparation of a variety of chemical intermediates. Thus, glucose will play a central role in feeding the so-called biorefinery, a future plant where chemical and biochemical processes are advantageously employed for the synthesis of intermediates and fine chemicals as an alternative to fossil-derived chemicals (Figure 21.1). 

Cellulose acid hydrolysis is an entry point for a biorefinery [139]. Recently, heterogeneous catalytic depolymerization of cellulose has received much attention [10, 140, 141). Solid materials modified with sulfonic acid groups have been widely attempted for cellulose hydrolysis. SuUbnated mesoporous sihcas [142], suUbnated carbon materials [69, 143-145], suUbnated carbon-siUca nanocomposites [146], and styrene-based sulfonic acid resins [147] have all been reported for sugar hydrolysis. 

Subhadra B. Grinson-George (2011). Algal biorefinery-based industry an approach to address fuel and food insecurity for a carbon-smart world. J Sci Food Agnc, 91, 2-13. 

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