Renewable resources agricultural

The agricultural and forest products industries are dependent on renewable resources for their existence. They are also acutely aware that air pollution can damage vegetation and, therefore, threaten their existence. Both industries have been exempt from many air pollution regulations in the past, but now they are finding these exemptions questioned and in some cases withdrawn (15). 

Xylan-type polysaccharides are the main hemicellulose components of secondary cell walls constituting about 20-30% of the biomass of dicotyl plants (hardwoods and herbaceous plants). In some tissues of monocotyl plants (grasses and cereals) xylans occur up to 50% [6j. Xylans are thus available in huge and replenishable amoimts as by-products from forestry, the agriculture, wood, and pulp and paper industries. Nowadays, xylans of some seaweed represent a novel biopolymer resource [4j. The diversity and complexity of xylans suggest that many useful by-products can be potentially produced and, therefore, these polysaccharides are considered as possible biopolymer raw materials for various exploitations. As a renewable resource, xylans are... 

Pretty J N, Ball A S, Xiaoyun Li and Ravindranath, N H (2002). The role of sustainable agriculture and renewable-resource management in reducing greenhouse-gas emissions and increasing sinks in China and India . Philosophical Transactions of the Royal Society A, 360, 1741-1761. 

The area interconnects several scientific disciplines (agriculture, biochemistry, chemistry, technology, environmental sciences, forestry, etc.), which makes it very difficult to have an expert view on the complicated interaction. Therefore, the idea of creating a series of scientific books, focusing on specific topics concerning renewable resources, has been very opportune and can help to clarify some of the underlying connections in this area. 

The total amount of renewable resources available around the world amounts to 170 GT/y (see Figure 10.6). Among them, 4.6 GT/y equivalent carbon are left in the fields as agricultural residues, while the world chemical industry currently consumes around 0.6 GT/y equivalent carbon (10% of the total current world... 

These systems offer the opportunity to produce hydrogen from renewable resources in the mid-term (five to ten years). Using agricultural residues and wastes, or biomass specifically grown for energy uses, hydrogen can be produced using a variety of processes. 

The worldwide increase in the price of petroleum and coal has created an interest in alternative sources of raw materials. Biomass is an attractive renewable raw material comprising all types of agricultural and silvicultural vegetation. These renewable resources have recently been considered major alternative raw materials for the chemical industry. 

Next, when considering the use of renewable resources, one must make note of the competing uses for land and the consequent impact on the environment, such as the competition between food production and industrial use for agricultural land, as exemplified by the growing biofuels industry or the deforestation of land for plantations of palm oil trees. This is a complex area where there is on-going national and international debate and where there are no easy answers. 

Michael R. Ladisch Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering... 

Michael R. Ladisch, Laboratory of Renewable Resources Engineering and Department of Agricultural and Biological Engineering, Purdue University. West htfiiyetie. IN. http //www.purduc.edu/. Biotechnology (Bioprocess Engineering)... 

An overview of cellulose-based chemicals and fuels systems is presented in Figure 1. In this cyclic system, demand for fuels and chemicals leads to the organization of factors of production (land, labor, capital, etc.) for the generation of biomass for use as a renewable resource. The plant culture activity is called silviculture if trees are the desired biomass or agriculture if herbaceous plants are grown... 

Cellulose is the most abundant renewable resource available for con- version to fuel, food, and chemical feedstocks. It has been estimated by Ghose (11) that the annual worldwide production of cellulose through photosynthesis may approach 100 X 109 metric tons. As much as 25% of this could be made readily available for the conversion processes. A significant fraction of the available cellulose, i.e., 4-5 X 109 t/year, occurs as waste, principally as agricultural and municipal wastes. Cellulose must be viewed, therefore, as an important future source of fuel, food and chemicals (see Table I). 

Cellulosic wastes have great potential as a feedstock for producing fuels and chemicals. Cellulose is a renewable resource that is inexpensive, widely available and present in ample quantities. Large amounts of waste cellulose products are generated by commercial and agricultural processes. In addition, municipal facilities must treat or dispose of tremendous quantities of cellulosic solid waste. 

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