Among all the different types of anaerobic digesters applied at full scale, UASB (Upflow Anaerobic Sludge Blanket) reactors present the best commercial acceptance. The success of these reactors is related to their capacity for biomass accumulation by settling without the need of a carrier. Good settling properties are obtained through the flocculation of the biomass in the form of dense granules with diameters up to several millimetres. Actually, as individual cells and granules have similar densities, the greater settling velocity of the latter is only related to its larger particle size. The study of this phenomenon has lead to the development of several techniques for characterizing the resistance of the granules, their porosity, settling properties, bacterial composition and organization, activity, nature and composition of exopolymers, as well as their size distribution. This last parameter is particularly useful for studying the physico-chemical factors promoting sludge granulation [38].

1. Search about 6 stainless steel screens with an aperture of about 2 to 0.149 mm for the test.

2. In a vertical stack such that always at the top this larger diameter with respect to the bottom.

3. Take and pass a sample of 25 mL of sludge by the sieves.

4. Washing the sludge with a buffer and phosphate to make them pass through the screens; separated by size.

5. Retrieve the granules, separately, to be retained in the meshes with a backwash of phosphate buffer solution (Table 1) and then determine VSS, FS and TSS [38].

Table 1. Phosphate buffer solution

Morphologically, artemia has fragmented body with leave and wide shaped appearance. It’s body consists of three compartments; head, thorax and abdomen, with total length of 8-10 mm and 10-12 mm in male and female respectively (Figure 1). Width of body is 4mm in both sexes. The exoskeleton of artemia is extremely thin (0.3-1 |j) and flexible that called" chitin" and it is connected to muscle from inner surface.

This animal is euryhalin and can tolerate high concentration of salty habitat. There is a glandular organ in back of artemia neck that named; "salt gland" or "neck organ" .This organ exudates extra salt from the body to environment. Salty organ extinct at maturity and then this function is performed by exopodits of legs.

Although there are some limitations in the living environment of artemia, like high temperature and high salinity and drought, this animal can tolerate these conditions by producing cysts and going to diapose until the condition become suitable, and then it will continue its living.

Salinity and temperature are two important factors for growth and survival of artemia.

Artemia can tolerate salinity even more than 250 g/l and suitable range of temperature is 6- 35°C. This crustacean has adapted itself with hard environmental conditions. In hypoxia, artemia increases the oxygen carrying capacity through the increase of the amount of hemoglobin. In this situation, body color turns red from original pale brown.

Physiological adaptation of artemia in high salinity is an effective defense method against predators using following mechanisms:

1. A powerful and effective osmoregulation system

2. Overcome high hypoxia in high salinity condition by higher pigmentation (inhalation pigments)

3. Production of embryos in diapose stage in cysts that can tolerate environmentally unfavorable condition.

• There is a lack of awareness of modern options for biomass energy. Knowledge on, for example, the competitiveness of life cycle costs of the biomass energy technologies (which can be the lowest cost option) is mostly absent.

• There is a perception that the traditional use of wood and charcoal must be reduced, so biomass energy is seen as something to be discouraged;

• There is little knowledge and no experience of the costs and benefits of the range of technologies available for modern biomass energy;

• Limited in-country capacity for renewable energy data collection and analysis is an important barrier for renewable energy project development;

1.2. The seaweed samples

1.2.1. Metal sorption capacity at different species of seaweed

The equilibrium sorption isotherms of La, Eu and Yb by three kinds of Ca-loaded seaweed biomass are shown in Fig. 1. Sorption experiment of Eu using U. p. could not be conducted in this work due to the lack of sample. The adsorption data obtained in this work were analyzed using Langmuir and Freundlich equations. The correlation coefficients (R2) of Langmuir and Freundlich isotherms for La, Eu and Yb using three kinds of seaweed biomass are shown in Table 1 along with other parameters.

From this table, it is found that R2 value for each datum is comparatively large for both isotherms. The value of 1/n less than unity indicates better adsorption and formation of relatively stronger bonds between adsorbent and adsorbate [10]. That is to say, favorable adsorption for La, Eu and Yb by these seaweed biomass used in this work is presented. Furthermore, it is noted that R2 values for these data are particularly large for Langmuir isotherm than for Freundlich isotherm. This result suggests that the adsorption on these samples mainly occurred by monolayer reaction. Therefore, the curves obtained from non­linear regression of the data by Langmuir isotherm are also shown in Fig. 1.

From Table 1, it is found that the data of qe for Eu and Yb by Sargassum hemiphyllu (brown algae) obtained in this study are similar to the result of species of Sargassum conducted by Diniz and Volesky [31], although qe for La is slightly small. Moreover, it is noteworthy that both Langmuir parameters: qe and A for La by Ulva pertusa (green algae) is large. Then, the comparison of sorption isotherms of La among three kinds of seaweed biomasses is shown in Fig. 2. From this figure, the sorption capacity of La by U. p. (green algae) is considerably large compared to that by other algae: S. h. (brown algae) and S. d. (red algae). It is generally known that brown seaweed is superior to red and green seaweed in metal sorption capacity for heavy metals such as Cd, Pb, Cu [34-35]; and such a high value

of qe (as observed in this work) using green algae have not been reported so far. In other words, it is significant outcome to find that Ulva pertusa (green algae) can be a promising biosorbent for removing La.

According to our previous work [32], in case of U, the mean concentration is the highest in brown algae and is the lowest in green algae among phyla (i. e., green, red and brown algae). However, as for the mean concentration of light REE (LREE) such as La, a slightly higher concentration is found in green algae; whereas the concentration of heavy REE (HREE) such as Yb or Lu in green algae is smaller than that in brown algae (as shown in the figure in our previous paper [32]).

Then, large sorption capacity of La by Ulva pertusa may be related to the character (or the constituent) of green algae; and it is possible that "La adsorption on Ulva pertusa" is due to "metal-specific", although further studies is needed to confirm the peculiarity by investigating the other combinations of metals and seaweed species.

♦ : Sargassum hemiphyllum, ■ : Schizymenia duby, ▲ Ulva pertusa. The curves obtained from non-linear regression of the data by Langmuir isotherm are also shown (S. h.; solid curve, S. d.; broken curve and U. p.; dotted curve). Data are mean±standard deviation (n=3).

Figure 2. Comparison of sorption isotherms for La among three kinds of Ca-loaded seaweed biomass at pH 4.0

SEM pictures of three kinds of Ca-loaded seaweed biomass before and after adsorption of lanthanum are shown in Fig. 3 and Fig. 4, respectively.

According to SEM observation, the surface of S. d. (red algae) seems to be relatively flat, whereas S. h. (brown algae) and U. p. (green algae) have more extensive surface area, although the specific surface area of the seaweed biomass could not be measured due to their small specific surface area. Furthermore, by comparing SEM pictures in Fig. 3 with that in Fig. 4, it is found that the morphology of S. h. and U. p. surface has hardly changed even

From the above observation, two kinds of biomass: Sargassum hemiphyllum and Ulva pertusa should be predicted to withstand the repeated use; and hence it can be a good adsorbent for lanthanides.

Preface

The increase in biomass related research and applications is driven by overall higher interest in sustainable energy and food sources, by increased awareness of potentials and pitfalls of using biomass for energy, by the concerns for food supply and by multitude of potential biomass uses as a source material in organic chemistry, bringing in the concept of bio-refinery. The present, two volume, Biomass book reflects that trend in broadening of biomass related research. Its total of 40 chapters spans over diverse areas of biomass research, grouped into 9 themes.

The first volume starts with the Biomass Sustainability and Biomass Systems sections, dealing with broader issues of biomass availability, methods for biomass assessment and potentials for its sustainable use. The increased tendency to take a second look at how much biomass is really and sustainably available is reflected in these sections, mainly applied to biomass for energy use. Similarly, Biomass for Energy section specifically groups chapters that deal with the application of biomass in the energy field. Notably, the chapters in this section are focused to those applications that deal with waste and second generation biofuels, minimizing the conflict between biomass as feedstock and biomass for energy. Next is the Biomass Processing section which covers various aspects of the second-generation bio-fuel generation, focusing on more sustainable processing practices. The section on Biomass Production covers short — rotation (terrestrial) energy crops and aquatic feedstock crops.

The second volume continues the theme of production with the Biomass Cultivation section, further expanding on cultivation methods for energy, the feedstock crops and microbial biomass production. It is followed by the Bio-reactors section dealing with various aspects of bio-digestion and overall bio-reactor processes. Two more chapters dealing with aquatic microbial and phytoplankton growth technologies are grouped into the Aquatic Biomass section, followed by the Novel Biomass Utilization section which concludes the second volume.

I sincerely hope that the wide variety of topics covered in this two-volume edition will readily find the audience among researchers, students, policy makers and all others with interest in biomass as a renewable and (if we are careful) sustainable source of organic material for ever wider spectrum of its potential uses. I also hope that further exploration of second-generation energy sources from biomass will help in resolving the conflict of biomass for food and biomass for energy.

Miodrag Darko Matovic,

Department of Mechanical and Materials Engineering, Queen’s University, Kingston, Canada

The reproductive period includes pollination, grain filling and ripening (BBCH 61-91). Significant changes in the number of productive shoots occur only under very adverse conditions. However, their uniformity and variability can still be changed by a number of factors.

Individual plants cannot be identified in a stand therefore, the analyses carried out are limited to shoot variability and indirect assessment of intra-plant relationships. Weight distribution is at the beginning of this period bimodal with a pronounced right side representing the productive shoots, and increasing left side representing the rest of non­reduced unfertile tillers which usually die during grain filling (Graph 3). Weight distribution of the ears is in this period usually unimodal and nearly normal shape.

Shoot weight can be considered as basic information used for indirect estimation of the reproductive value and productivity of its ear. Rawson and Evans [31] reported narrow linear relationship (r = 0.94) between shoot weight at heading and a final number of grains in an ear. Our investigations also revealed highly significant linear correlation between shoot weight and number of embryos after flowering (r = 0.91-0.94). Therefore, proportion of shoot weight per one embryo can be considered as a basic factor determining the number of grain embryos in ear [32]. Narrow correlations between the amount of the aboveground biomass formed until flowering (BBCH 60) and number of grains per area unit of a stand and also yield are reported by a number of authors [33-36].

The amount of the biomass of productive tillers at the flowering (anthesis) can thus be used for prediction of the final stand yield. Duration of leaf area and redistribution of assimilates from stem to kernels is very important with respect to yield formation. Longer duration of the active green area supports higher yields. Many papers have been devoted to physiological processes of grain formation, most of which being based of the source x sink approach. Great attention has been paid to supplying of embryos and filling grain with carbohydrates and nitrogen substances, and to the possibilities of better availability of these sources for grain filling by breeding and growing management [37-40].

If grains are comprehended as modules, similar rules of the population biology of plants can be applied to their formation as to tiller formation [41]. Weight distribution of grains can have different shapes (both bimodal and asymmetric unimodal) in dependence on stand structure and growth conditions. One of the most important quality parameters is grain uniformity. It has an effect on grain yield (proportion of grain above 2.5 mm mesh) and bulk density. Both parameters are important at processing of food wheat and malting barley. Variability in weight of grains is influenced by relationships on individual levels of the hierarchic structure of a cereal plant — tillering node and ear structure [42].

Only a limited number of cultivation measures have been performed during grain filling. Qualitative N rate is usually applied to winter wheat at heading. Later application of N fertilizers is exceptional. Sometimes, N is applied in a tank-mix of urea together with fungicides against ear diseases. Cultivation measures are, therefore, predominantly oriented to maintenance and performance of production potential of stand which has been formed at previous stages of growth and development. Following factors are important for yield formation and grain quality during the reproductive period:

— amount of the aboveground biomass formed and its structure,

— active green area and duration of its functionality,

— course of translocation and assimilate redistribution processes.

When assessing the nutritional status of plants, looking up the nutritional balance of the plant, however, this goal can not be reached when using the traditional methods of nutritional diagnosis, such as the sufficiency range and critical level, because, both of them lead into account only the individual concentrations of nutrients in the plant, with no relationship among these nutrients.

The Diagnosis and Recommendation Integrated System (DRIS) provides the relationship between nutrients through dual ratio (A/B and/or B/A). Thus it is feasible by calculating DRIS index to obtain the nutritional balance (Baldock & Schulte, 1996). In addition to the DRIS index, which may take positive and negative values, there is the nutritional balance index (NBI), which is the sum in modulus of the DRIS indices from a sample and thus the lower the value of the NBI would be more nutritionally balanced in the crop.

Despite of the diagnosis of nutritional status, the DRIS can be a useful tool to indicate situations where yield is limited by other factors than nutritional, however, it does not discriminate the factors that would be limiting the yield. In crops that have low yield and low NBI it is expected that other factors were limiting productivity, not being a limitation by the nutritional status of the plant (Beaufils, 1973).

The Nutritional Balance Index (NBI) was calculated by summing the value in module of the index generated in the sample. This NBI may be useful to indicate the nutritional status of the plant. The higher the NBI, the greater the nutritional imbalance (Beaufils, 1973; Mourao Filho, 2003). The average NBI generates NBIa (Nutritional Balance Index average), according to the formula below:

NBI = l DRIS A + I DRIS B + I DRIS C + -+|7 DRIS N

NBl

NBIa = ■

n

Where: n is the number of DRIS index involved in the analysis.

The NBI has been used to prove the effectiveness of the DRIS system in diagnosing the nutritional status of the plant, because the greater the relationship between NBI and yield better the diagnostic system response, to point out the nutritional status of plants (Silveira et al. 2005b) (Figure 1). Guindani et al. (2009) used the NBI to select the reference population to compose DRIS norms relating to the NBI tracks yield and the yield range that had the highest coefficient of determination (R2) was selected as the reference population.

As already mentioned above bioenergy interest has been greatly increased in last period. Thus, at present factors may influence the prospects for bioenergy:

• increases in crude oil prices,

• concerns for enhancing energy security matters, by creating de-centralized solutions for energy generation,

• concerns for climate change and global warming, but also to

• preserve non-renewable resources,

• promotion of regional development and rural diversification by creating jobs and income in usually underdeveloped rural areas,

For the developing and transition countries as Bosnia and Herzegovina, the increased deployment of modern biomass based systems, as a reliable and affordable source of energy could be part of the solution to overcoming their current constraints concerning GDP growth. In any case, production and use of biomass should be sustainable in terms of the social, environmental and economic perspectives.

Success of biomass based projects depends on the understanding of the stakeholders on the all levels which have to understand biomass resource base, its purposes and potential use in some other competitive branches, benefits and disadvantages of use of such material for energy purposes on sustainable manner. All these aspects point strongly to the importance of coordination and coherence of policies directing the supply and use of biomass for different purposes [11]. Only with policy support, established promotional mechanisms and adequate investments environment it is possible to achieve certain level of the bioenergy involvement in energy balance of certain region or country.

An appropriate political and economic strategy of the biomass utilisation for bioenergy (including biomass price policy, subsidies) within the country would evidently encourage the creation of new jobs not only in forestry, agriculture, and wood processing industry but also in other industry branches. Today, it is obviously that issue of biomass utilisation for bioenergy has political, economic and environmental dimension. Thus, governmental regulations are indispensable to provide and secure stable economic and ecologic framework conditions [3].

According to findings from the book "European Energy Payhways" (2011), there are two pathways to sustainable Energy systems in Europe [12]:

• Policy pathway,

• Market pathway.

Policy pathway takes its departure from the EU Energy and Climate Package and has a strong focus on the targeted policies that promote energy efficiency and energy from renewable energy sources (RES). The Market Pathway leaves more of the responsibility for transforming the energy systems to the market, where is cost to emit GHG is dominating policy measure.

Both pathways require significant changes in the infrastructure of the energy system and related power plants, transmission networks, fuel infrastructures, buildings and transportation systems, which is not simple, particularly for transition countries like Bosnia and Herzegovina.

Chosen policies and their applications have direct and indirect impacts on the competitiveness of bioenergy compared with other sources. It is important to increase the knowledge about the design of different tax and support regimes to get the desired effect. The implementation of bioenergy is not solely influenced by financial instruments that support the construction and operation of bioenergy plant, but also depends on policies for agriculture, forestry and the environment as well as public support.

Taking into consideration variety of biomass types coming from different sectors, as agriculture, forestry, wood processing industry, food industry, municipal waste, crucial aspect is an adequate assessment of the resources. Obtaining as much as possible accurate data about available biomass resources is demanding job because potential variations in quantities from year to year. Only theoretical estimated biomass potential for biomass resources in certain area is still not indicative data for the project development, because technical availability depends on a lot of other factors as terrain configuration, equipment selection and type. From the other side economic and market potential depends on a lot of various factors which can be transportation fuel prices, or some other market related issues.

Due to that a lot of tools have been developed in order to give accurate and clear picture about available biomass resources. Tools as GIS (Geographical Information System) are in use today in order to identify biomass resources and their availability for technical exploitation taking into consideration roads infrastructure in certain area, as well as identification of the location for biomass energy plant or some other production plants, taking into consideration access to heat or power supply networks, etc.

Achieving a secure fuel stream that satisfies the business drivers of economy, efficiency and effectiveness whilst remaining within acceptable parameters for environmental impact, quality and future sustainability will be essential to future project development.[13]

Mentzer et al. coined commonly used and well-adopted definitions of supply chains. They define the supply chain as "a set of three or more entities (organizations or individuals) directly involved in the upstream and downstream flows of products, services, finances, and/or information from a source to a customer" [13].

Sustainability of the biomass based energy projects, strongly depends on the establishment of the whole energy supply chain, from the row material at the beginning until final product in a form of energy, synthetic fuel. Biomass is also utilized for food, feed, materials and chemicals, and bioenergy interacts with these areas; in many instances such interactions are synergistic, but they may also be in conflict.

Biomass use for bioenergy can take place immediately in the place of production or in the user’s or intermediate producer’s /processing firm’s site. It must be economically acceptable, and it depends on the available quantities, the transport volume before and after processing, and the required technical equipment, including operation expenses. In all discussions about that, the following should be essential:

— the purpose for which the generated energy is used;

— the availability of biofuels in the close vicinity, including quantity, calorific value, processing and supply costs;

— the efficient use of that energy from biofuels, and the chances for its continuous sale to others.

On this basis, an economic model, including the selection of the equipment, has to be drawn up, and its feasibility should be verified in consideration of potential subsidies and earnings arising from selling energy to others.

The overall purpose of biomass supply chains for energy use is basically twofold: (1) Feedstock costs are to be kept competitive and (2) Continuous feedstock supply has to be ensured [14].

Future renewable energy projects will have to meet much more stringent regulations and guidelines on all areas of operations, from environmental emissions, feed stock materials, process residue disposal or recycling through to employment conditions.[13]

A significant barrier to the use of biomass in some regions is the public concern that its production is non-sustainable. In some instances, such as if harvesting native forests at a rate greater than their rate of natural regeneration, this view is clearly correct. There are simply some sources of biomass that for a variety of reasons (such as their aesthetic, recreational, biodiversity, water cycle management and carbon stock qualities) should never be used for energy purposes [14]

A key constraint to the expansion of biofuel production is the limited amount of land available to meet the needs for fuel, feed, and food in the coming decades. Large-scale biofuel production raises concerns about food versus fuel trade-offs, demands for natural resources such as water, and its potential impacts on environmental quality, biodiversity and soil erosion,.

There are also a number of economic and ecologic problems that could be solved before the economic and environmental effects will be visible in a community. The problems include:

• insufficient sensitisation of companies;

• insufficient sensitisation of the communities and their limited influence;

• insufficient knowledge of the decision-makers in the economy about the assets and opportunities that arise from biomass use for bioenergy;

• insufficient financial resources for changing the way of handling biomass resources;

• insufficient macro-economic incentives.

Biomass energy in Bosnia and Herzegovina has an important role mostly in terms of fuel wood for production of heat energy. This holds particularly true in the areas where the rural sector has a prominent role in the population structure, since historically the rural population in all areas was using the biomass for heating and/or cooking. Biomass in the form of fuel wood and charcoal is currently an ever increasing source of energy in BiH, whose average consumption is estimated at 1,323,286 m3 per annum. However, the degree of efficiency of the energy conversion devices is very low. Unlike in households, biomass consumption is low in other sectors such as, for example, agriculture, trade and industry. Fuel wood is important mostly in the rural areas and small towns where no public heating network is available. In some areas of Bosnia and Herzegovina, the share of biomass in household heating reaches the level of up to 60% (parts of East Bosnia). As in many cases for development countries, the fuel security and rural development potential of bio fuels that tends to be of most interest. At this micro scale sustainable development drivers are more social-economic. Strategic approach for the rural areas has to offer new opportunities, in a sense that modern village is not only as food producer, with all difficulties related to competitiveness of its products, but also competitive energy producer, or supplier, which gives new dimension of its sustainability.

Most of the cities and rural households have its own heat supply systems, mainly low efficient boilers, which gives a chance to local producers of the biomass boilers and HVAC equipment as well as pellet and wood chips producers. This aspects will be analyzed, particularly in the context of the situation when the most large municipalities in Bosnia and Herzegovina has been signed "Covenant of Mayors" taking the real obligation for local GHG emission reduction.

There are some of district heating systems which have problem with sustainability because of low efficiency and use of expensive liquid fossil fuels. The analysis were shown that is possible to reconstruct some of them and switch the fuel to biomass, issuing lower prices of the heat produced as well as CER (Certified Emission Reduction) because such projects can be attractive as CDM.

There are a lot of small municipalities in Bosnia and Herzegovina with large physical potential of biomass and developed forestry and wood processing industry. It is easy to show that small municipalities in Bosnia and Herzegovina (with 10.000 to 20.000 inhabitants) with centralized wood processing industry can satisfy their all energy needs from its own wood waste, but also start some new business activities based on the available biomass..

Some estimations has shown that 50% of forest biomass this resource could supply medium scale CHP installations (5 MWe +) delivering power to grid and heat to residential/ commercial/ industrial users. The installed capacity would be around 21 MWe and annual output would be 149 GWh and 213 GWh of electricity and heat respectively. If half of the scenario where potential of 7,66 PJ would be available for bio-energy industry, or medium — scale CHP installations, delivering power to grid and heat to residential / commercial / industrial users, 106 MWe installed capacity that would generate 745 GWh electricity and 1.065 GWh heat annually would be supported. Technical and economy aspects of the potential use of some technologies as steam turbines, steam engines, Stirling Engines, Organic Rankine Cycle and gasification technologies in the circumstances of Bosnia and Herzegovina will be analyzed.

Modern market opportunities offers many promotional mechanisms for bioenergy based projects. Some of them which are of the high importance has been analyzed: ESCO (Energy Service COmpanies) and Feed-in tariffs, because they already exists in Bosnia and Herzegovina. Due to that some of the aspects related to promotional mechanisms will be analyzed.

There are no any co-firing biomass based technologies in Bosnia and Herzegovina (except of a small demonstration unit at the Mechanical Engineering Faculty of Sarajevo), but it can became interesting because some analysis shows that use of 50% of estimated forest residues would result in the production of 149 ‘green’ GWh within existing solid fuel power facilities, which are mainly from the seventies and use low rank lignite coal.

Biomass from the wood processing industry and forestry, together with agricultural and other forms of biomass is a significant energy source and due to that deserves careful planning and estimation because it can became one of the important economy drivers.

The palm oil mill is self-sufficient in energy, using waste fibre and shell as fuel to generate steam in waste-fuel boilers for processing, and power-generation with steam turbines. As an example, The Federal Land Development Authority (FELDA) palm oil mill in Sungai Tengi, Selangor, Malaysia, employs the standard oil extracting process [28]. In the standard milling process, used in the factories with a milling capacity of over 10 tonnes of raw material per hour, water is added into a digester [29]. More than 19.7 million tonnes FFB were processed in 2000 [28]. The standard sized mills processing 60 tonnes/hour of fruit bunches normally produce 40 tonnes/hour of steam. Part of the steam is used to generate 800 kW of electricity and the rest is used as process steam. It is estimated that the total generating capacity of the mills is about 200 MW [28]. Typically palm oil mills use fibre and shell as a boiler fuel to produce process steam for sterilisation, etc and also possibly for electricity generation to supply electricity for other parts of the mill complex. These oil palm wastes make oil palm mills self sustainable in energy. The shell and fibre alone can supply more than enough energy to meet the mill’s requirements using low pressure relatively inefficient boilers. The EFB have traditionally been burnt in simple incinerators, as a means of disposal and the ash recycled onto the plantation as fertiliser. However, this process causes air pollution and has now been banned in Malaysia, furthermore, under this route of disposal, no energy is recovered. Alternatively EFB can be composted and returned to the plantation, or returned directly as mulch. Figure 2.1 shows a proposed plan for the operational process and product of the palm oil industry if EFB is used as fuel beside palm shell and fibre.

Referring to Figure 2.1, as the fresh fruit bunches reach the processing plant, the sterilisation process begins with the steam temperature at 140oC, pressure at 2.5 to 3.2 kg/cm2 for 50 minutes [28]. After this process, the stripping process will take over. In the stripping process, a rotating divesting machine is used to separate the sterilized oil palm fruit from the sterilized bunch stalks. The empty fruit bunches (EFB) will fall in the collector and are brought to the burning place as a fuel. After the bunches have been stripped, the sterilised fruits are fed into a digester where water at 80°C is added. This is performed in steam- heated vessels with stirring arms, known as digesters or kettles. The most usual method of extracting oil from the digested palm fruit is by pressing. The type of press used in this palm oil is the screw type press.

The crude oil extracted from the digested palm fruit by pressing contains varying amounts of water, together with impurities consisting of vegetable matter, some of which is dissolved in the water. Centrifugal and vacuum driers are used to further purify the oil before pumping it into a storage tank. When the digested fruit is pressed to extract the oil, a cake made up of nuts and fibre is produced. The composition of this cake varies considerably, being dependent on the type of fruit. The cake is given a preliminary breaking treatment before being fed into the nut/fibre separator called depericarper. When the fibre has been separated from the nuts, the latter can then be prepared for cracking. Any uncracked nuts must be removed and recycled and the shell separated from the kernels. The waste fibre and shell are also transported to the burning place as a fuel. The kernels are packed and sold to kernel oil mills.

Palm oil mills in Malaysia typically meet most of their electricity and process steam requirements by burning some of the wastes, with energy for start-up generally being provided by back-up diesel [13,28,30]. Not all of the wastes are burnt. For each kg of palm oil, electricity consumption is around 0.075-0.1 kWh and steam demand around 2.5 kg. This represents a steam to electricity ratio of around 20 to 1 and could be met by burning 0.3-0.4 kg of waste. As the boiler efficiency is only around 70%, actual consumption is correspondingly higher [31]. Little effort was made in the past to optimise process steam consumption or boiler or turbine efficiency, as the fuel was substantially treated as a waste that was incinerated to be disposed of. The electricity co-generated in Malaysian palm oil mills therefore only amounts to roughly 1-1.5 billion kWh or less than 2% of 2003 generation of over 82 billion kWh. To illustrate the kinds of waste available, the process flow of a palm oil mill is summarised in Figure 2.2 (simplified from [28]) and a typical product stream distribution is shown in Table 2.1 (adapted from [30]). The total product stream distribution in oil palm mills is greater than 100% in wet basis as extra water is added during the process, for example during sterilization with steam. Most of this water ends up in POME.

As can be seen in Table 2.1, the moisture content of fresh EFB is very high. Typically it is over 60% on a wet EFB basis. Consequently, it is a poor fuel without drying and presents considerable emissions problem that its burning is discouraged by the Malaysian government. Palm oil mills therefore typically use shell and the drier part of the fibre product stream, rather than EFB, to fuel their boilers [31]. Palm Oil Mill Effluent (POME) is so wet that it is usually treated by anaerobic digestion before the discharge of the effluents [32].

For each kg of palm oil, roughly a kg of wet EFB is produced. As over 60% of the wet EFB consists of water, and the heating value of the dry EFB is roughly half that of palm oil, the energy obtainable from the EFB product stream amounts to roughly 0.2 kg of oil equivalent per kg of palm oil. Based on Malaysia’s 2005 palm oil production of 15 million tonnes, the energy value of the EFB waste is therefore around 3 million tonnes of oil equivalent, which would amount to $1.2 billion for an assumed $400 per tonne ($55 per barrel).

As mentioned before, most crude palm oil mills harness the energy from the fibre and shell in steam boilers. However, the introduction of advanced cogeneration (combined heat and power) also can play a role in combatting climate change, as well as introducing significant economic benefits. Through cogeneration, the costs of energy will be cut because it uses fuels at high conversion efficiencies can reduce the emissions of carbon dioxide and other pollutants. However, it is only worth doing if one can sell the additional surplus energy (electricity) to customers at an economical rate. Today, the ability to sell electricity into the local grid provides an opportunity to turn waste into a valuable commodity.

• Modern biomass energy services are dealt with by various ministries, agencies and institutions, on different levels, making good coordination between them a necessity if efficient use of limited human and financial resources in an area is to be achieved;

• Generally speaking, government decision-makers (who have access to and control the budget) have little interaction with those at operational level. Operational lines of communication between operation and decision-making levels need to improve within government agencies;

• Limited geographic distribution of suppliers limits access to renewable energy technologies (hardware);