1- Sustainability: a Single Concept and Different Approaches.

Let us proceed with the definition of the concept of sustainable development, given by the World Commission on Environment and Development [16]. "Development that meets the needs of the present without compromising the ability of future generations to meet their own needs".

This concept has two dimensions: a geographical / national-cultural dimension referred to in the previous definition by the words: "present generations", and a temporal dimension, as referred to in the same definition by "future generations". The first dimension, which we will call for simplicity the geographical, includes both the North and South. This dimension is usually not given due attention in literature and discussion on sustainable development (and sustainability in general) to the extent that it seems sometimes as if the industrialized countries are searching for the sustainability of their own standards of living. But if we take the geographical dimension into consideration, we will find that there are great differences in the contexts in the North and South. To start with, the issue of sustainability is not really a priority in many countries in the South, simply because the deterioration of the living conditions at present evokes the feelings of apathy to the future and to the future generations. Concepts like sustainable development or sustainability are far from being operationalized. They are mostly confined to come intellectual spheres and discussions in formal institutions and donor organizations active in these South countries. This doesn't mean that the issue of sustainability is irrelevant to these countries; it points to the fact that we need to develop different approaches or paths to sustainability in the North and South.

Proceeding from the vision of sustainable development, it is needed to change the consumption and production patterns currently prevailing in the industrialized countries in the North. What is needed in the South is to stop their replication! If what is needed in the industrialized countries is to search for new innovation fronts or develop innovation in the innovation process itself [15], what may be needed in the South is to restore the capability of innovation itself. Let me mention below several ingredients of what may be called an approach to sustainability in the South.

Confrontation with modem forms of cultural imperialism managing via mass communication media to propagate in the South the unsustainable styles of life currently prevailing in the industrialized countries.
Recognition of the cultural specificity of different regions / societies. This is the first step to tap the great rich heritage of knowledge on local resources and sustainable ways of their use in each local community. Not only that, the recognition of cultural specificity will bring into action those cultural values conducive to sustainability in each culture.
Building of endogenous scientific and technological capabilities that may help each region / society / culture find its own modem version of sustainable development, relying on its own cultural traditions, technical heritage and resource endowment.
Restructuring and strengthening of the social fabric of the local community, perceived as a socio-cultural ecological system in its own right and, rebuilding of the traditions of participative democracy within the local community and changing of the image of the citizen from an isolated atom and a mere consumer and passive recipient of the "fruits" of development to a member of the local community, who takes part in all the decisions that have to do with his personal and communal life.

2- Renewable Material Resources: A New Information System is needed.

2.1- Classification of Renewable Material Resources.

Fig. 1 illustrates a proposed simple classification of renewable material resources. This figure demonstrates the wide variety of the available renewable resources worldwide. It also points to the wide variety of ecological conditions, within which these resources could be available. Such a classification could be of help in constructing a hierarchy for the renewability of these resources and their availability in different regions of the world. Besides, the proposed classification could be of help in the planning of fields of applications of the renewable material resources. The wide variety of secondary products of these resources deserves special attention. Within the framework of the traditional market rationality emphasis was placed on the primary products of renewable material resources. This short-sighted vision has led in general to the neglect of use of most of the secondary products of these resources, which has had deleterious effects on the environment in many cases. In the following sections our talk will be limited to the renewable material resources of plant origin, which are in some references called: lignocellulosic raw materials.

2.2- Agricultural Residues : a High Priority Area of Concern.

The last years have witnessed a worldwide surge of interest in the agricultural residues. Most of these residues were actually burned in the field. For example, the estimated annual bone-dry weight of the residues in North America alone is 350 million tons [6]. This gives an idea of the scale of the problem of burning of such huge quantities of resources every year. Therefore, the pressure exerted by local environmental movements forced the authorities in many countries to issue legislation preventing the burning of such residues. Besides, the increasing pressures against the cutting of rain forests has led to the increase of the prices of wood and decrease of its availability in the world markets [10]. This has led to the renewal of interest in agricultural residues as an alternative source of fibers, and hence in the planting of fiber crops, neglected, for example in Europe, from the sixties of the last century with the appearance of nylon and other synthetic fibers [9]. It is estimated now that a hectare of land planted by fiber plants renders a crop of 4-5 ton of fibers, i.e., 50% more than the corresponding fiber crop, if it were planted by short rotation-trees, such as, poplar or eucalyptus [9]. New expressions like "It is Down Again in the Grain Forest" [2], and "It is Second Spring of Panel Industry" [9], illustrate the new wave of interest in these resources. They are no longer called '"residues", which is incompatible with the marketing approach, but: Agrofibers [2] or AG-Fibers [6], i.e. as an industrial input like well-known industrial fibers. Products, made from these agrofibers are now being marketed as Tree-Free Products [2], emphasizing their environmental friendliness: both in relation to the decrease of pressure on cutting of forests and the quitting of burning of agricultural residues. Seven particleboard factories, operating on agricultural residues, have been opened in North America within the last few years and 12 more are planned to be constructed in the future [I].

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2.3- Information on Renewable Material Resources: For Whom and for What?

There is in general a great shortage in information on renewable material resources. As far as the agricultural residues of annual crops are concerned, there is some information on their availability within the available statistics on the agricultural production on the national level. But this information is not accurate. In most cases no scientific methodology was applied to access their availability, which depends on: the plant species, ecological conditions and conditions of agriculture. As far as the products of pruning of trees are concerned there is almost no available information, except for the date palm [5]. The same is valid for other products of natural flora. Moreover, the information on these resources is usually available on the national and sectoral levels only and in a scattered form.

We need to develop community - or province - centered data bases giving clear picture of the local availability of renewable material resources of plant origin; whether they are elements of natural or man-made flora, primary or secondary products. Such data will help realize the integrated use of locally available renewable resources. It may be uneconomic to establish an industry on a single resource, but the combination of different locally available resources may provide good economics for industrial utilization. This is especially important for many secondary products, which are either perishable or bulky or both and are thus uneconomic to transport to far sites for farther processing.

We need to establish a site on the Internet for the exchange of information on the availability of renewable material resources and the potentialities of their use in different applications. Who may be interested to be a partner in such an initiative?

Ministries of agriculture and investors in growing of forests, annual crops, etc., who could give and/or sponsor the accumulation and building of accurate information on the availability of these resources; from the local to the national and regional levels.
Institutions, involved in the R&D efforts on the use of renewable material resources in different applications.
Local authorities down to the municipal level, environmental movements and NGOs, who are interested in finding solutions to the environmental problems, associated with the neglect and / or burning of agricultural residues.
Entrepreneurs, interested in making investments in projects, directed to the use of renewable material resources in different applications.
Marketing agencies, who show special interest in supporting the marketing of products, made from renewable material resources.

3- Why a Workshop on Renewable Material Resources?

3.1- Renewable Material Resources are Potentially Inexhaustible.

Therefore, the propagation of their use could be consonant with the sustainable development. If the extraction rate of these resources is not too high, and under suitable conditions, such as clear air, enough water and a fertile soil, renewable resources can be in principle extracted eternally [12]. The stocks of non-renewable resources, in contrast, are negatively affected by extraction. Now 40 minerals, including copper, lead, zinc, gold, mercury, tin and silver are classified as pessimistic minerals that will soon be exhausted [12].

3.2- The Renewable Material Resources Perform Ecosystem Functions Before They Are Harvested.

For instance, plants and trees contribute to the regulation of the composition of the atmosphere, have a clear recreational aspect and produce oxygen [16J. The non- renewable resources, on the contrary, do not have clear ecosystem functions before extraction.

3.3- The Renewable Material Resources are Within the Reach of People Everywhere.

The renewable material resources are not concentrated in one region, so that there is always a share of them for each local community. These resources could be, in most cases, endogenously grown, extracted, processed and manufactured. They need relatively simpler techniques. Therefore, the local community has the chance to interact with these resources without necessarily the intervention of the government or transnationals. Therefore, the propagation of sustainable use of renewable material resources could serve as an efficient tool for the endogenous development of local communities and the decrease of the gap between the rich and the poor, especially in the South, where the technical heritage associated with the renewable material resources has not yet been lost, as in the North [12].

3.4- From a Life-Cycle Perspective: The Use of Renewable Material Resources is More Compatible with the Ecosystem Cycles.

This is valid when the renewable resources are compared with the non-renewable along the successive stages of their life cycle.

3.4.1- During Extraction.

The renewable material resources are generally extracted at the earth surface, on land or at sea. This means that they can often be extracted without strong impact on ecosystems. The non-renewable resources, however, are generally extracted by mining or drilling, which often causes pollution and degradation of ecosystems [12].

3.4.2- Energy Requirements During Manufacture.

The production of materials; based on renewable resources, generally requires less energy than the production of materials like plastics and metals. This can be shown by comparing the Net Energy Requirements (NER) values in GJ/ton for material derived from renewable resources with those from non-renewables. Compare for example, NER for dried and sawn wood (3-1), chipboard (11-8) and plywood (16.0) with steel (23.4), aluminum (198.4) and polystyrene (38.2) [12].

3.4.3- The Post-Consumption or Disposal Stage of the Life Cycle.

The biomass is inherently biodegradable; hence, this characteristic is generally transferred to the materials like wood products and natural textiles, based on renewable material resources. In contrast, materials based on non-renewable fossil fuels, like plastics, and metal ores are generally not biodegradable. Therefore, if not recycled, they should be dumped in the disposal stage of their life-cycle or incinerated, which has a negative environmental effects. The characteristic of biodegradability is especially important for products with a short life span (e.g., packaging) and/or materials that are used in a dissipative way (e.g., lubricants), which should be preferably made from renewable material resources [12].

3.5- For the Aforementioned Considerations it is Necessary to Support the Sustainable Use of Renewable Material Resources as Substitute to Non- Renewable Resources.

How could such an objective be attained? Product-oriented environmental policy instruments should be developed on the state, regional and international levels to stimulate the substitution of nonrenewable by the renewable resources. The application of such instruments should be based on scrupulous life cycle analysis of products made from non-renewable and renewable resources. A good example of such policy instrument is the General Preferential System of the EU [4]. By means of this system preference could be given to products from developing countries, which are produced in a more environmentally friendly way. Examples are the use of coconut fibers (in Indonesia) for hydraulic engineering and other building purposes, as well as the use (as in Netherlands) of coconut fiber products like packaging material, floor coverings and filling of mattresses [4].

4- Guidelines for Selection and Use of Renewable Material Resources.

Within the framework of sustainable development, the renewable material resources need rational conscientious management. Such management proceeds from the understanding of the inherent aspects of the resource itself, the socioeconomic and cultural features of the context, where the resource exists or will be used, and the basic ideas underlying the concept of sustainable development. Following are the main guidelines for the selection and use of renewable material resources.

4.1- Classify the renewable material resources hierarchically, according to their inherent structural properties [16], for example as follows: -

• Trees in tropical forests
• Trees in temperate forests.
• Short-rotation trees (e.g., eucalyptus and poplar)
• Cultivated crops.
o Climax species
o Pioneer species

Such a classification could be made in different countries and/or regions reflecting the wide variation in the ecological conditions all over the world.

4.2- Classify the forms of use or applications of resources hierarchically.

Stages higher in the hierarchy represent resource use or application that keep open the possibility of use or application, at lower stages, after disposal (e.g., end of use or application at the given stage) [16]. Thus, the hierarchy of a use or application of a resource could be imagined as stages of a cascade.

4.3- Proceeding from the understanding of the inherent structural aspects of the resource, try to choose the first use or application to be at the highest possible stage of the use/application cascade. This is what is called the matching principle |161. For example, according to Fig. 2., wood should be first used, after the ecosystem phase, in building as beams. After disposal, or end of a certain stage, the relevant form of the resource should be reused again at the highest possible stage, i.e. in furniture in case of wood, and so on. If each resource is successively used at all the possible stages of its cascade the total potential of the resource will be fully used. This is what is called the full utilitzation principle [16].

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4.4- As contrasted with the dominant market rationality, associated with the use of only isolated specific agents or components of a resource, the rest (dominantly the major part) being turned into waste, the whole resource should be used [18]. This means that we will deal with the whole crop/plant trying to make full use of its potentialities through finding out the best areas for use for each of its components. This is what may be called the whole resource use principle. For example, the cotton plant should not be only a source of cotton fibers for textiles. The stalks could be an excellent material for particleboard and MDF [7], and the foliage for fodders industry, beat or composting.

4.5- Try to allocate as many stages of processing and/or manufacture of the renewable material resources as possible near to the sites of growing or extraction of these resources. This has first of all a social dimension; the application of such a principle may contribute to the realization of more just social distribution of the economic benefit from industry between rural (where resources are extracted) and urban (where end products are usually manufactured) areas. Besides, this principle is associated with the economics of application of the resource in several ways- The application of processing or manufacturing stages near to the site of growing or plantation of the resource is a strong evidence of the economic significance of the resource. TTlis may create the motive to improve the techniques of plantation or expand the project of plantation itself. For example, the establishment of a palm-midrib blockboard factory m the New Valley govemerate in Egypt proved in the first years of operation to be a very effective means to motivate the farmers to serve (prune) their palms more regularly, and to care more for planting more palms. The parallel increase in the availability of the resource and the escalation of the field of its application will help to keep its price at the level of extraction competitive for a long time. Beside, this measure gives guarantee for the actual - and not the potential - renewability of the resource. In addition, many renewable material resources are either bulky or perishable or both. Therefore, their processing in site will either increase their bulk density or preserve them against biological degradation or both, making their transportation economically feasible and thus facilitating their processing in further sites. Over and above, processing in site may be a mean for using the economic advantages of cheap collection and storage areas in the rural areas, the cheap and sustainable solar energy in drying of these resources, and the cheap equipment and appropriate technology available in rural areas. These factors add to the economic feasibility of the application of the resource contributing, at the same time, to the sustainability of its application [7].

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5- The Renewable Material Resources: a New Challenge for Engineers.

5.1- Introduction.

Throughout the course of man's history, the renewable material resources played a pivotal role in man's life. Different cultures of the world evolved hand in hand with certain elements of the flora in each region. For example, papyrus was pivotal in ancient Egypt. It was used, not only for food and making writing paper, but also in making of sailing boats. Columns in the ancient temples in Egypt were made in the form of bundles of papyrus stems, symbolizing the significance of papyrus in the life of ancient Egypt. In Asia bamboo, rattan and rice were essential ingredients of the way of life there. In Europe wood played a dominant rule in all the walks of life. Before the Industrial Revolution factories were built beside dams on rivers. Huge wooden wheels were used to transfer the motive power of water collected behind the dams to machines in factories. It wasn't until the First and Second Industrial revolutions that a drastic shift occurred in the dependence of man on renewable material resources. The shift to steam power, then electricity, the invention of the internal combustion engine and the revolution in industrial chemistry and in steel manufacture were the main factors behind the shin to reliance on non-renewable
resources.

At present the curricula in science and engineering classes deal mainly with steel and concrete and to a lesser extent with other metals, ceramics, plastics, and glass. There is a clear negligence of renewable material resources in these curricula, which means that the renewable material resources are not considered materials in the engineering sense. In engineering a material is usually denned as a substance with consistent, uniform, continuous, predictable and reproducible properties to the extent that it can be relied upon in the satisfaction of certain required performance criteria [131. The difference, for example, between a steel I-beam and a wooden log is that you can accurately predict the performance of the former under a certain load, whereas, you couldn't in case of the latter. This example well synthesizes the engineering look to a material but doesn't explain what is engineering? Engineering is the process of transformation - via imaginative thinking and design process and then manufacturing processes - of a material from its state as an isentropic material extracted from nature to a, more or less, isotropic material having reliable and predictable performance. The stainless steel wasn't found in its present form in. nature: it needed a long history of engineering effort to transform iron oxide as extracted from nature to stainless steel.

Let us now come to the main question: why were the renewable material resources less engineered until now as compared, for example with steel? If we categorize materials to two categories: price-driven (i.e., these materials which costs dictate the market), and performance-driven (i.e., those materials, for which properties dictate the market), then the renewable material resources are price-driven materials [13]. The use of wood, for example, in a piece of ftimiture doesn't require certain strict mechanical properties as a beam in a building or a member in a machine. Fig. 3. Illustrates a comparison between price-driven materials, such as wood, with other performance driven materials in military and aerospace industries.

We engineers need to change our perception of materials. Our preconceived idea that the renewable materials resources are the only materials with property shortcoming is not entirely accurate [13]. Table 1 shows the properties of several commonly used engineering materials. Wood and other lignocellulosics swell as a result of moisture, but metals, plastics and glass also swell, as a result of increase in temperature. Lignocellulosics are not the only substances that decay. Metals oxidize and concrete deteriorate as a result of moisture, pH changes and microbial action. Lignocellulosics and plastic bum, but metal and glass melt and flow at high temperatures. Lignocellulosics are excellent isolating substances, whereas the insulating capacity of other materials ranges from poor to good. Furthermore, the strength-to-weight and stiffhess-to-weight ratios are very high for renewable material resources when compared with non-renewable resources. Therefore, within the impending environmental crisis our globe is facing, we need to develop a new more judicious vision of the renewable material resources, so that these resources play the role they should in a contemporary sustainable way of life. This is really a new challenge for engineers!

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5.2- Towards an Engineering Approach to Renewable Material Resources.

5.2.1- Learning from nature: mimicking of structural properties of renewable material resources as a mean for improvement of performance of engineering structures.

One of the advantages of renewable material resources as compared with the non-renewable is that they have structures (macro), which can be a source of information and technical inspiration for engineers. The study of the structures of renewable material resources may show us how to engineer materials with high functionality, in terms of mechanical properties and multi-functionality and yet with high compatibility with natural processes [12]. Let me give an example from our experience with the date palm midrib. Fig. 4-a Illustrates the structure of the midrib with respect to the palm, whereas Fig. 4-b give a general view of its cross-section.. As distinguished from wood (dicotyledon), the palm midrib (monocotyledon) does not have radial rays, i.e., there is no cross linking between the fibrovascular bundles being the structural unit of the midrib. Therefore, the fibro vascular bundles are linked together by the flexible parenchyma tissue, shown in the figure. This structural aspect of the midrib, together with the form of the cross-section gives the midrib its distinguished property of flexibility and toughness. This explains how these midribs tolerate millions of cycles of loading through their life and do not break, even when subjected to the harsh strong storms of the desert. Fig. 4-c gives a detailed view of the anatomical structure of the midrib. It is clear that as we move from the periphery inward, the diameter of the fibrovascular bundles increases and their number decreases [11]. Thus, the percentage of fibers, responsible for the structure strength, increases dramatically as we move from the center of the midrib to the periphery. This structure is astonishingly compatible with the distribution of normal stresses in the cross-section of beams subject to bending loads. Therefore, the structure of the palm midrib inspires us to design beams from composite layers to combine the properties of high strength (outside layers) with toughness, (inside layers), which may be required, for example, in design of bridges.

5.2.2- The discovery of new properties of the same structure of the renewable material resource to satisfy new modern needs.

Referring again to the example of the palm midrib. It has been shown by the analysis of the anatomical structure [II], Fig 4-c, of the palm midrib that the epidermal layer is distinguished with a very high intensity of small diameter fibrovascular bundles, so that there are only a few parenchyma cells in-between. This aspect of structure, as well as the layer of wax covering the midrib epidermis, makes the midrib resistant to dehydration. In addition, the palm midribs enjoy high heat isolation property. Therefore, it is suggested to use the palm midribs with its leaflets in roofing in low-cost housing, sheds and in ecologes.

5.2.3- Reduction of the unpredictability of performance of the resource through the selection of species and ecological conditions when the resource is planted, age and harvest time of the resource, as well as its structural arrangement.

A lot of research has been devoted to the investigation of the properties of different bamboo species [14]. Similar effort has been done on different date palm species in Egypt [15]. It is clear that there are significant variations between different species of the same resource. Ecological conditions, e.g., climate and soil, as well as the practice of silviculture have also their influence on the resource properties. Therefore, if we use, for example, culms of the same bamboo species, cultivated at the same conditions and having the same age, we will probably have less variation in properties.

The palm midrib has a cross-section that decreases from below upward. In making mats from midribs for roofing, villagers used to lay the midribs successively one opposite to each other, so that the cross section of the whole mat is homogenized. This is a simple technique for the homogenization of the structural properties of the midrib. Another technique we used is to divide the midrib into three distinguished equaling parts: top, middle and base: each of them having different cross-section dimensions and mechanical properties. This may lead to the manufacture of mats of more homogeneous structure from the top, middle and basal parts of the midrib.

5.2.4- Transformation into a new intermediate material having a more homogeneous structure. This intermediate material can be used in development of more engineered products from the renewable resources.

Fig. 5 illustrates the aforementioned idea. The transformation of the original resource into a new intermediate material or form firstly decreases the variation of properties of the structure. For example, the inner part of the midrib, whether square, rectangular or circular in form, has much more uniform structure of each fibro vascular bundle and distribution of these bundles within the new form more than in the original material. This leads to the homogenization of properties of the material. Secondly the new form gives new imagination. As soon as we thought, for example, of the square form of the midrib, our imagination went to new fields of products: the blockboard and then the lumber-like product from the palm midrib [1?1, and finally the table top and parquet. The same holds for the circular cross-section, the midrib strand having tensile strength approaching that of steel (^14 N/mm2) [8], particles and fibers. Therefore, it is possible through the appropriate manufacturing process to transform a renewable resource from an isentropic material to an isotropic material and an engineered product.

5.2.5- Change of the composition and structure of the resource to give it new properties to satisfy new modern needs.

There is a wide range of techniques that could be used for the aforementioned purpose. Retting is a well-known popular technique, used for the preservation of bamboo against attack by insects. The soaking in fresh water reduces the starch content in bamboo and thus reduces the food for insect and fungi [3]. The impregnation technique is successfully used with wood and could be used with palm midribs and bamboo for improving the mechanical properties, as well as the fire rctardance property.

5.2.6- Surface treatment of the resources to give them new properties for certain applications.

Lamination is a wide-used technique for imparting certain properties for renewable material resources. For example, the three-layer particleboards are usually laminated with melamine-impregnated paper to increase their resistance to swelling when used in humid conditions (kitchens and bathroom furniture). The plywood, used for shutter concrete, is usually laminated with phenol-impregnated paper to resist the penetration of water into the wood plies, which may influence the quality of the surface of the concrete. The phenol paintings are very essential for parquet, in order to impart the water repellence property to the upper wooden or bamboo layer.

5.2.7- Combination with other resources.

There is a great potentiality for the use of renewable material resources in making composites that have uniform and predictable properties enjoying at the same time the quality of being environment-friendly. Biocomposites could be made from renewable material resources using green chemistry, i.e., using adhesives based on renewable material resource, such as starch and soy proteins. The natural fibers are more and more required to be used for reinforcement of plastics, as a substitute for fiber glass, which is neither combustible, nor biodegradable. There are already many applications of flax and jute fibers in this field. The natural fibers have also a good chance to be used for reinforcement of gypsum in gypsum-fiber boards, a prospective field in future.

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6- References

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4. Consultancy and Research for Environment Management (CREM). Department "Product Trade and Environment", November 1996.

5. Date Palm Midrib Utilization Project Final report. Center for Development of Small-Scale Industries in callobration with IDRC, Faculty of Engineering, Ain-Shams University, Cairo, October 1995.

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11.Megahed, M.M. and H.I. El-Mously. Anatomical structure of date palm leaves' midrib and hs variation across and along the midrib. IUFRO XX World Congress, August 6-12, 1995, Tampere, Finland.

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American Chemical Society, 1992.

14. Shuen. C. W. and others. Relationships between anatomical characteristics and permeability properties in Taiwan grown bamboo species. Bamboo and its uses. International symposium on industrial use of Bamboo., Beijing, China, Dec., 1992.

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17. Taysseer A. M., H. I. El-Mously and M. M. Megahed. A new lumber-like product from date palm leaves' midribs. Proceedings of the 5th European Conference on Advanced Materials and Processes and Applications, Vol. 4Characterization and Production/Design, Maastricht, 21-23 April, 1997-

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