The leaf area deployed governs the interception of solar radiation, which is pivotal in the production ecology equation presented above. The sooner that the leaf area index (LAI) can reach a peak value, the sooner optimal growth can take place because radiation interception is linearly related to biomass production (Linder 1985; Turnbull et al. 1988; Dovey 2005). In short rotations, such as bio-energy crops, the time period from planting until deployment of peak LAI may make up a substantial portion of the full rotation length, and it is thus of critical importance minimise this period. The rapid deployment of a peak LAI is aided by high planting densities, but as described in Sect. 5.3, expensive harvesting operations also place a limit on the stand density that can be used, because of harvesting piece size constraints.

Rapid deployment of peak LAI can be achieved by intensive silvicultural management which will boost the availability of soil water and nutrients to young transplants. Management of competing vegetation and fertilization at time of establishment are two critically important operations in this regard (Little and Van Staden 2003; Wagner et al. 2006; Little et al. 2007; du Toit et al. 2010). Fertilization should be site — and crop specific to ensure best economic returns.

Hardwood stands usually have a very high demand for nutrients in the period up to and including canopy closure, e. g. Laclau et al. (2003). Research on fertilization of short-rotation Acacia and Eucalyptus tree crops in warm climates initially focussed on relatively small applications (of mainly N and P) that would boost stand productivity (Williams 1928; Beard 1952; Schonau 1983, 1984; Herbert and Schonau 1989). Fertilization at (or soon after) establishment is commonly done by commercial tree growers because of the relatively low input costs and large gains on highly weathered, P deficient sites, or alternatively, gains due to Type B responses eluded to earlier in this chapter (Barros et al. 1992, 2004; Herbert 1996; du Toit 2002; Gonsalves et al. 2008; Bennett et al. 1997; du Toit et al. 2010; Maree et al. 2012). Application rates for this type of fertilizer application usually include P at
10-40 g per tree (Gonsalves et al. 2004; du Toit et al. 2010). In specific cases, responses to additional N (0-30 g N per tree) K (0-15 g per tree) and small quantities of B has been observed (Gonqalves et al. 2004; du Toit et al. 2010). This need for N applications depends on the soil conditions (Noble and Herbert 1991) and site preparation/slash management options (du Toit and Dovey 2005; Smith and du Toit 2005; du Toit et al. 2008). Gonqalves et al. (2004, 2008), as well as Gava (1997) make the point that N and K applications are becoming more common in eucalypt plantations that have undergone several crop cycles, apparently due to increase nutrient losses in harvesting the possible depletion of readily mineralisable N.

In pine plantations, P fertilization during the establishment phase (commonly at levels between 20 and 60 kg/ha) may lead to large growth responses, but this is mainly limited to highly weathered, P deficient soils (Donald 1987; Xu et al. 1995a, b; Fox et al. 2007a; Kotze and du Toit 2012). Furthermore, pines in subtropical and warm temperate climates have generally shown the biggest responses to nutrient additions during mid or late rotation periods (12-20 years of age), when nutrient demand is much larger than supply (Donald 1987; Payn et al. 1988; Turner et al. 1996; Carlson 2000; Fox et al. 2007a; Kotze and du Toit 2012). Levels of 200­400 kg ofN and 50-100 kg of P commonly give good results in mid-rotation pines. Fertilization after 12 years of age may be too late in very short rotations grown for biomass, especially if they are planted at higher stand densities. However, it appears that younger pine stands may have sufficient capacity to take up moderate nutrient applications, judging from the responses to P, K and Mg applications have been documented at time of canopy closure (age of first pruning in most stands under conventional management regimes) where acute deficiencies existed (Kotze and du Toit 2012). This finding may be of importance to short rotation pine stands that are under pressure from nutrient depletion: Economic responses can be obtained by such early fertilization efforts.

The application of hydrogels can also improve water availability during a critical period following planting (Viero and Little 2006). In addition to minimising compe­tition, vegetation management also ensures a more homogenous crop, and this will result in the greater partitioning of NPP to above-ground biomass production, which is an added benefit.

Johann F. Gorgens, Marion Carrier, and Maria P. Garcia-Aparicio

7.1 Introduction

The rendering of bioenergy products such as heat, fuel and electricity requires the conversion of sustainably produced biomass feedstock by means of thermochemical and biological processes. Such processes convert feedstocks into higher energy — value products amenable to industrial and domestic applications. This chapter deals with the nature of the conversion processes, the biomass feedstock requirements for these processes and the resulting quality of bioenergy products. In addition, the present chapter will also consider the application potential of different conversion technologies to both industrial and rural areas in the Southern Hemisphere.

Conversion of biomass feedstocks is a key step in bioenergy production. The value of bioenergy products is related to their suitability for particular energy applications, which is determined by the interaction between characteristics of the feedstock and the conversion process applied. Thermochemical conversion processes are primarily combustion, pyrolysis, gasification and direct liquefaction, while biochemical conversion of biomass involves hydrolysis to monomeric sugars and organic acids, followed by fermentation/digestion to liquid and gaseous bio­fuels.

Technology selection for biomass conversion represents a key decision in the formulation and selection of a bioenergy production process. These decisions are driven to a large extent by the availability of feedstocks and market demands. The present chapter will consider technologies applicable to tree-based biomass produced in tropical regions, as discussed in Chaps. 2, 3, 4, 5 and 6, while serving as an introduction to Chap. 8, where the impact of tree-quality on these

J. F. Gorgens (H) • M. Carrier • M. P. Garcia-Aparicio

Department of Process Engineering, Stellenbosch University, South Africa

T. Seifert (ed.), Bioenergy from Wood: Sustainable Production in the Tropics, Managing Forest Ecosystems 26, DOI 10.1007/978-94-007-7448-3__7,

© Springer Science+Business Media Dordrecht 2014 conversion processes is investigated. Aspects of technology selection and feedstock are included in the global bioenergy analysis in Chaps. 9, 10 and 11 as well as case studies presented in Chap. 12.

Hemicelluloses are short chains of branched hetero-polysaccharides composed of both hexoses and pentoses. D-xylose and L-arabinose are the main constituents of pentosans (xylans), while D-glucose, D-galactose and D-mannose are the main constituents of the hexosans (mannans). The major hemicelluloses component of softwood is mannan-based whilst the hemicelluloses in hardwoods are xylan-based. Hemicelluloses comprise 20-25 % of the material in hardwood and 7-12 % in softwoods. The close association of hemicelluloses with cellulose and lignin in the fibre cell walls contributes both rigidity and flexibility. The type and amount of hemicelluloses vary widely, depending on plant material, tissue type, growth rate, growth conditions, storage and method of extraction. A study of Pinus resinosa Ait has shown that the xylose content in earlywood was about 1-2 % higher than in latewood and the ratios were reversed for mannose (Panshin and De Zeeuw 1980). No difference was found between early wood and late wood for galactose, arabinose, and glucose in young trees. Analysis of successive growth increments within the tree in Pinus radiata D. Don showed a 3 % reduction of hemicelluloses from pith to bark and from the top to the butt of a tree. A maximum hemicelluloses content of about 11 % was found near the pith and toward the top of the tree. Glucose and mannose were shown to increases with age and decrease upwards while arabinose, xylose and galactose were shown to decrease with age and increased with height. Compression wood contains about 8-9 % more hemicelluloses than normal wood (Haygreen and Bowyer 2007).

The design of ENs is a major determinant of their effectiveness. For example, stepping-stone patches within ENs, provided they are large enough, are useful for some of the larger animals using the ENs (particularly large mammals and birds). However, continuous corridors of good quality habitat in ENs are still preferable, as they allow smaller, less mobile, animals, such as frogs, insects and spiders, to use the linkages. In fact, these small animals use these corridors as habitats in their own right, giving the corridors themselves their own inherent biological value (Pryke and Samways 2011).

ENs function at the landscape scale. So, to be effective, they need to incorporate as many landscape features as possible. The inclusion of as many habitat types, as well as landscape features, is fundamental to good EN design. For example, grassland ENs with indigenous forests embedded within them have high biological value, not only because of the additional species in the forests themselves, but also because there are more species in the associated grasslands (Pryke and Samways 2011). This is due to grassland-indigenous forest interface, which is seemingly so essential for some species.

Recently, there has been much interest in the edge effect between the transformed plantation blocks and the corridors of the ENs. One reason for this is that ENs have more edge than occurs naturally because of the linear nature of corridors (Koh et al. 2010). Understanding these EN edge effects is important for conservation planning, in that it determines minimal width of corridors. Edge effects are caused by structural changes along the edge boundary (Cadenasso et al. 2003; Harper et al. 2005), as well as through changes in soil moisture and nutrients (Li et al. 2007). Over time, secondary effects, such as roads and invasion by exotic plants and animals, can further deteriorate the habitat along the edge.

The influence that transformed areas have on the ENs is often a two-zoned effect: the edge zone, which is influenced by the interface between a transformed area and a natural one, and the interior zone, where species richness, abundance and assemblage composition are no longer influenced by the distance to the edge (Cadenasso et al. 2003; Ries et al. 2004). Disturbance on the edge allows generalist species to disrupt natural systems (Pinheiro et al. 2010; Ivanov and Keiper 2010), although given enough space, it gives way to a more valuable interior zone (Slawski and Slawska 2000; Hochkirch et al. 2008).

Edge effects of exotic plantation blocks on indigenous grasslands are larger in size than that between natural forest patches and grasslands (Wilson et al. 2010), while there seems to be no general edge effects between natural Afromontane forest and its associated grassland (Kotze and Samways 2001). The type of transformed landscape also contributes to the extent of the edge, and determines those species found in it, as has been shown with changes in edge zones in rural versus urban contexts (Vallet et al. 2010) and in edges between different age classes of timber plantation blocks (Armstrong and van Hensbergen 1994).

Although some biodiversity responds positively to the edge, and many species have their habitat at the edge (van Halder et al. 2011), it is the interior zone which is of most concern. The reason for this is that the interior is harder to conserve, as it requires enough space for edge zones to completely surround it. When corridors are too small, they consist entirely of edge zone, without the important interior zone. When edge effects for a variety of arthropods are tested between plantation blocks and adjacent grasslands, there are many different responses, but overall edge effects for all arthropod groups are absent beyond 32 m into the grassland corridor (Pryke and Samways 2011).

Although this 32 m edge zone is a conservative estimate of grassland edge effects around timber plantation blocks, this result suggests that corridors of less than 64 m will be mainly edge and have specific conservation value only as disturbed sites. In fact, interiors of the corridors have similar biodiversity to reserves, suggesting that corridors with widths over 64 m have a biodiversity profile similar to that of nearby reserves (Pryke and Samways 2011). Provided corridor width is wide enough, these corridors have considerable biodiversity value. The 250 m suggested by Pryke and Samways (2001) is appropriate, as this incorporates a great deal of interior space for more sensitive species. Furthermore, a network of larger habitat corridors, as suggested by Samways et al. (2010), will reduce the area of edge zones across the entire network. When planning agroforestry landscapes with conservation in mind, we need to consider the edge zone around intensive land-use areas as a transitional area from a transformed to a natural ecosystem.

The concept of corridor and ENs is based on connectivity to enable organisms to move through the fragmented landscape (Hilty et al. 2006). For arthropods, these concepts need to be put into perspective, especially as dispersal in most species is strongly linked to resource-searching behaviours (foraging, mate or lek location etc.) (Baguette and Van Dyck 2007). Corridors need to be habitats that allow less mobile arthropods to use them as pathways for dispersal. This means that these corridors need to be of high enough habitat quality to encourage resource use (e. g. feeding, breeding etc.). The best way to ensure this high quality habitat is to manage the ENs optimally.

Anton Kunneke, Jan van Aardt, Wesley Roberts, and Thomas Seifert

2.1 Introduction

The aim of this chapter is to provide an overview of methods of estimating woody biomass from inventory information.

In understanding any resource, the extent (spatial localisation) as well as the amount of resource should be estimated. Inventory is the term used in forestry practice for assessing the timber resource. The result of an inventory should establish at least three values. The first is the estimated mass or volume of resource per unit area, for a given time period, the second value is the total area of the resource, and the third is an error value (accuracy and precision) associated with the estimate. In a heterogeneous resource a subdivision of the resource in classes is also necessary. Common subclasses could be vegetation types (e. g., 0-30 % tree cover, 30-50 % tree cover, broadleaved forest and savannah, etc.) or qualitative age classes (e. g., young, semi mature, mature). For instance, naturally regenerated forests, as opposed to commercial plantations, contain all age classes in a single stand at the same time. An inventory in those forests will therefore provide a range of diameter classes, and should rather concentrate on size than age.

Conventional forest inventory typically attempts to establish the volume of utilisable wood or bio-energy in the forest stand. The minimum information necessary for bio-energy use is a map with the available biomass and a value in

A. Kunneke (H) • T. Seifert

Department of Forest and Wood Science, Stellenbosch University, Stellenbosch, South Africa e-mail: ak3@sun. ac. za

J. van Aardt

Centre for Imaging Science, Digital Imaging and Remote Sensing Group,

Rochester Institute of Technology, Rochester, NY, USA

W. Roberts

BioCarbon Partners, Cape Town, South Africa

T. Seifert (ed.), Bioenergy from Wood: Sustainable Production in the Tropics, Managing Forest Ecosystems 26, DOI 10.1007/978-94-007-7448-3__2,

© Springer Science+Business Media Dordrecht 2014 kg m“2 for each section (stand or subdivision) on the map, since the localisation of the biomass will guide all further steps of harvesting (Chap. 6). Biofuel can be described by characteristics such as energy content (MJ kg_1) and heating value (MWh kg_1). Furthermore, it might be desirable to know the percentage of components of biomass, e. g., leaves, twigs, branches, bark and stem wood, since the comprehensive biomass composition determines the ash content, a critical factor in bio-energy conversion (Chaps. 7 and 9) and is a major determinant for the export of nutrients and thus stand sustainability (Chap. 10). Models that estimate biomass composition, based on inventory data, are thus relevant additions to the typical inventory information (Chap. 3). Biomass resource assessment or inventory is in essence then no different from conventional inventory in that the quantity and quality of biomass needs to be estimated. It differs in that the mass and not the volume has to be estimated and that the quality parameters differ. This chapter will concentrate on procedures to estimate the mass and quality parameters needed, while briefly hinting at the associated errors associated with these.

Three main approaches could be followed to provide biomass assessments:

• Sample plot-based methods using terrestrial light detection and ranging (LiDAR) scans (TLS) or standard methods, as with conventional timber inventory, related to diameter and height measurements in sample plots. The sample plots are assumed to be representative of the area in the inventory and models are used to predict the component fractions of the stand in the inventory.

• Aerial surveys based on LiDAR and photogrammetry estimates of tree param­eters (number, height, crown size, etc.) at the stand level, applied to models to predict total biomass and biomass components of the stand.

• Space or aerial survey methods of estimating total aboveground biomass directly. This is possible with SAR and LiDAR methods, as well as optical infrared sensing in combination with models. The total aboveground mass is a single value, which requires additional modelling to predict a breakdown of component fractions for the stand.

This chapter will describe the methods used in measuring parameters, while the upscaling and modelling of component fractions will be dealt with in Chap. 3.

Miombo woodland is a significant biome covering about 10 % of the African land masses (ca 2.5-4 million km2 depending on definition, White 1983; Millington et al. 1994). It is the prevalent vegetation throughout the Zambezian region where soil is freely drained but rooting environment is restricted (see Campbell 1996; Fig. 4.1). Floristically and physiognomically it is very different from other woodland types, and is nearly always dominated by Brachystegia species, either alone or with Julbernadia species or Isoberlinia species (Geldenhuys and Golding 2008). Most miombo woodlands are semi-deciduous, but some are completely deciduous while others are almost evergreen (White 1983; Geldenhuys and Golding 2008). Most miombo dominant species are light demanding and showing some degree of fire resistance, but cannot survive repeated fires (Syampungani 2008). A distinction is made between Wetter Miombo (rainfall > 1,000 mm, canopy height > 15 m, floristically rich) and Drier Miombo (rainfall < 1,000 mm, canopy height < 15 m, floristically poor) (Geldenhuys and Golding 2008). Wet miombo woodland occurs over much of eastern Angola, northern Zambia, south-western Tanzania and central Malawi in areas receiving more than 1,000 mm rainfall per year (Frost 1996). The canopy height is usually 15 m, reflecting generally deeper and moister soils which create favorable conditions for growth (White 1983; Frost 1996). Brachystegia floribunda, B. glaberrima, B. taxifolia, B. wangermeeana and Marquesia macroura are widespread in this vegetation type (White 1983). It is also associated with widespread vegetation namely; dry evergreen forest and thicket, swamp forest, evergreen riparian forest and wet dambos (Fanshawe 1971).

Most miombo species are semi-heliophilous, show some degree of fire- resistance, but however, the dominants cannot survive repeated fierce fires (Lawton 1978). The principal canopy associates are Afzelia quanzensis, Anisophyllea pomifera, Erythrophleum africanum, Faurea saligna, Marquesia macroura, Parinari curatellifolia, Pericopsis angolensis and Pterocarpus angolensis (Chidumayo 1997). Several species of Uapaca and Monotes occur scattered in miombo as shrubs less than 10 m tall (White 1983). They are frequently dominant on shallow soils and in secondary miombo, and are abundant in the scrub woodland that represents the ecotone between miombo and the edaphic grassland of waterlogged depressions (White 1983).

The dry miombo woodland occurs in southern Malawi, Mozambique and Zimbabwe (White 1983; Frost 1996). Brachystegia spiciformis, Brachystegia boehmii, and Julbernardia globiflora are often the only dominants present (White 1983). The dry miombo has three subtypes namely: (i) Brachystegia boehmii-

Democratic Republic of Congo

Angola

Zambia

Botswana

South Africa

Fig. 4.1 Miomboecoregion (Source: Timberlake and Chidumayo (2011))

Brachystegia spiciformis-Brachystegia utilis (ii) Brachystegia manga-Julbernadia woodland and (iii) Brachystegia spiciformis-Julbernadia woodland (Chidumayo 1997). B. boehmii-B. spiciformis-B. utilis is associated with Diplorhynchus condylocarpon, Lannea spp. Ochna spp., and Pseudolachnostylis maprouneifolia as understorey species while the B. manga-Julbernardia woodland has Diospyros spp., D. condylocarpon and Ochna spp., as the common understorey species.

When FT are harvested in a structured manner, and terrain is easily accessible, it is possible to use terrain-going chippers. These are commonly built on a standard forwarder chassis or adapted agricultural tractor fitted with a crane to feed the chipper and a large bin or skip to hold the chips. The orientation of the chipper intake (forward or sideways) has important connotations. Row thinnings imply a largely linear method of working, and a forward oriented chipper easily receives the butt-ends of the FT lying in the row, allowing the machine to move forward at approximately the same rate as the tree is being fed into the chipper. A forward oriented chipper is mounted in front of or under the cabin, leaving the entire loadbed available for a bin, which typically accommodates around 15 m3 (~3,500 kg).

Side oriented chippers are placed behind the cabin, and take up storage space, but subject the cabin to less vibration and noise and have better mass distribution. Side oriented chippers require that the young trees have been laid into the stand perpendicularly to the strip road. A further disadvantage is that the machine cannot move forward before the tops of the trees being chipped clear the closest residual trees in the stand. The side oriented chipper is better suited to chipping tops from later thinnings where a harvester has been used and where more space is available. Maximising bin size is crucial to improving machine utilisation. Large, bulky bins can; however, cause damage to the residual stand, especially if the machine needs to reverse out of the striproad (Fig. 6.5).

In-fleld chipping requires some form of chip storage at the roadside landing. Tipping the chips onto the ground for later collection decouples production from transport, but results in some losses into the ground, and potential soil contamina­tion, as well as the need for a wheeled loader or self-loading trucks (cranes with buckets) in order to move the chips to the conversion plant. Tipping the chips into a container requires firstly that the bin can be raised to sufficient height (~2.5 m) and that the logistics around the supply and exchange of containers is well managed.

Steam explosion is one of the most studied pretreatments since its development for commercial scale application (Masonite technology) and has been applied success­fully on a variety of lignocellulosic materials (Ballesteros et al. 2004; Taherzadeh and Karimi 2007). This process combines thermal (high temperature), mechanical (sudden vaporization of the water) and chemical (hydrolysis of hemicelluloses) alteration of biomass. During steam explosion the biomass is exposed to saturated steam at high pressure for a period of time (seconds to several minutes) after which it is suddenly depressurised. The water penetrates into the lignocellulose structure and hydrolyses acetyl residues from the hemicelluloses, which in turn promotes partial hydrolysis of the hemicelluloses. The sudden depressurization induces the mechanical rupturing of fibres and redistribution of lignin. As a result, lignocellulose is more accessible to enzymes and the solubilised hemicelluloses can be easily recovered by filtration. However, solubilised lignin and sugars can be further degraded into compounds that can be inhibitory to further bioprocessing.

The concentration of degradation products, and therefore the extent of toxicity, depends on the source of biomass, the severity of the pretreatment (often measured as the combination of temperature and residence time) and properties of the specific enzymes/microorganisms involved in the subsequent biochemical conversion.

Despite its feedstock versatility, steam explosion is not very effective on soft­wood materials owing to its lower acetyl content. The addition of an acid catalyst (H2SO4, SO2) has been recommended as an option to improve the performance of steam explosion on softwoods and other woody materials, which will result in reduction of pretreatment severity and maximise sugar yields (Ewanick et al. 2007; Garcfa-Aparicio et al. 2011). Similarly, the application of CO2 with organic acids has been suggested to reduce the severity of pretreatment, in turn reducing hemicellulose degradation into inhibitory compounds (Gfrio et al. 2010).

Liquid hot water is a hydrothermal treatment that employs compressed hot water (pressurised and above saturation point) at high temperatures to disrupt the lignocellulose structure. Compared to steam explosion, this treatment is very effective for hemicellulose solubilisation, leading to reduced inhibitor formation when the reaction pH is kept between 4 and 7. However, the concentration of hemicellulose-derived sugars is reduced due to the higher water input.

Ammonia fibre explosion (AFEX) combines the use of liquid anhydrous ammonia at high temperature (60-100 °C) and pressure. After a variable period of heating, sudden decompression provokes the expansion of ammonia gas altering lignocel — lulose structure with limited inhibitor formation. Contrary to other thermochemical pretreatments, AFEX treated material is a solid with a similar carbohydrate compo­sition to the raw material but is more digestible by cellulases and hemicellulases. Moreover, the residual ammonia after recycling can reduce nutritional requirements in the following fermentation step. Although it has been suggested that AFEX alters lignin, reducing its ability to bind enzymes (Kumar and Wyman 2009), this pretreatment is not very effective when applied to woody biomass (Kumar et al. 2009).

In ammonia recycle percolation (ARP) the biomass is subjected to aqueous ammonia (5-15 %, w) in a flow-through system (approximately 5 ml/min) at high temperatures (normally 170 °C). ARP solubilises hemicelluloses and lignin providing cellulose-enriched residues with high digestibility. ARP has shown to be efficient in increasing digestibility of hardwoods, waste paper and softwood pulp mill sludges (Gfrio et al. 2010). Sugar degradation is minimal during ARP, but the solubilised lignin can be toxic for microorganisms.

Wet oxidation involves the exposure of biomass to oxygen or air at high temperatures (170-200 °C) and pressures (10-12 bars) for short periods of time (10-15 min). It solubilizes hemicelluloses (mainly in polymeric form) and lignin (Hendricks and Zeeman 2008). The phenolic compounds are further degraded to carboxylic acids but furans formation is lower in comparison with steam explosion or liquid hot water.

The choice of pretreatment depends on the type of feedstock and the desired biofuel output. The majority of pretreatments generate a material known as slurry which consists of a solid fraction enriched in cellulose (and lignin, depending on the pretreatment) designated as the water insoluble fraction (WIS) and a liquid fraction or prehydrolysate containing the sugars solubilised during the pretreatment (mainly hemicellulose-derived sugars). Depending on the severity of the pretreatment, the sugars can be further degraded into furans that, coupled with the solubilised lignin and acetic acid released from the hemicelluloses, impact negatively on biochemical transformation. For this reason, most studies separate slurry into the separate liquid and solid fractions to optimise the conversion of each fraction into biofuels. Current research focuses not only on the development of detoxification processes but also on the cultivation of robust microorganisms that are able to effectively convert hexoses and pentoses in slurry into biofuels. This aspect seems to have less impact for biogas production given the higher tolerance of methanogenic bacteria to inhibitors (Hendriks and Zeeman 2008).

Cori Ham and Theo E. Kleynhans

9.1 Introduction

Energy from biomass is one of the oldest forms of energy used by mankind due to its general availability and low technology requirements (Buchholz et al. 2007). Wood was used all over the world as the principle source of energy until about the mid nineteenth century after which it had been replaced by more efficient and convenient energy sources such as coal, gas and electricity. The move towards more convenient fuel types was especially prevalent in industrialised countries but wood has remained the dominant source of energy in developing countries where people are less able to afford alternative sources of energy and their associated technology (Arnold et al. 2003).

The move to more convenient types of energy in the industrial world set the scene for two crisis events in the late twentieth century that would refocus the world’s outlook on bioenergy. The first event in the early 1970s was the so called “Energy Crisis” caused by the rise in fossil fuel prices which triggered an increased focus on fuelwood resources. Attention was drawn to the fact that in developing countries, fuelwood was the principle source of energy and that projected use levels could be above sustainable replacement levels, leading to a total depletion in wood supplies. Assumptions were made that fuelwood use was a major contributor to deforestation and forest degradation, and subsequent solutions were based on providing sustainable sources of fuelwood through forestry programmes (Ham and Theron 1999).

C. Ham (H)

Department of Forest and Wood Science, Stellenbosch University, Stellenbosch, South Africa e-mail: cori@sun. ac. za

T. E. Kleynhans

Department of Agricultural Economics, Stellenbosch University, Stellenbosch, South Africa

T. Seifert (ed.), Bioenergy from Wood: Sustainable Production in the Tropics, Managing Forest Ecosystems 26, DOI 10.1007/978-94-007-7448-3__9,

© Springer Science+Business Media Dordrecht 2014

The second crisis event, in the 1990s, was the realisation that the reliance on convenient fossil fuels has an effect on the CO2 levels in the atmosphere and could lead to a change in the world’s climate. The so called “Climate Change Debate” prompted the search for more sustainable energy sources that would reduce CO2 outputs. Energy from biomass is seen as one of the more sustainable sources of energy and it is expected that future development of bioenergy will take place in two directions. The first being an increase in bioenergy production in developed countries to try and reduce CO2 levels, and secondly an increase in total bioenergy production in developing countries to cope with population growth and a move towards modern bioenergy conversion technologies (Buchholz et al. 2007).

The events of the 1970s and 1990s highlighted the potential positive effect on carbon balances of substituting fossil fuels with bioenergy and also emphasised the negative environmental costs associated with unsustainable fuelwood harvesting in terms of forest loss and degradation (FAO 2005). Accelerated tree planting programmes were promoted as a technical supply side solution to the “Fuelwood Gap” of the 1970s and modern bioenergy technology can be seen as a way of moving people, especially in developing countries, away from primary firewood use to more efficient bioenergy conversion technologies. The positive relationship between access to energy and human well-being has led many to conclude that improving access to modern energy, such as electricity, is a key component of poverty reduction and development (Buchholz et al. 2007).

It can be assumed that bioenergy will continue to play an important role in global energy supply as a source of renewable energy. Solid biomass contributes 45 % of the primary renewable energy in member countries of the Organisation for Economic Co-operation and Development (OECD) and provides more than 90 % of the energy needs for many developing countries (Sims 2003, ex Buchholz et al. 2007). One of the important questions related to the future of bioenergy production is how the developed and developing world will balance the positive and negative externalities associated with bioenergy use. Pure technical solutions might not be enough as it is important to consider that human well-being depends on more than just energy need and should consider every aspect of socio-economic development (Ham et al. 2008). This chapter will explore the current role that bioenergy plays in socio-economic development. It will begin with a summary of biomass as a primary source of energy in developing countries and progress to a review of the role of the rural poor in modern day bioenergy enterprises.

The system boundaries of a product, process or service system need to be specified in terms of several dimensions (Tillman et al. 1994), namely:

• Boundaries in relation to the natural system

• Geographical boundaries

• Time boundaries

• Boundaries within the technical system

In general, activities included in the flow model of a technical system (the inven­tory model) are activities under human control. However, when a flow enters

(or leaves) human control, it also enters (or leaves) the technical system. While it is relatively easy for non-renewable resources such as oil and minerals to be defined in the ‘cradle’, i. e., during the extraction thereof, the boundaries for renewable resources, between the technical and the natural system, are less easy to draw. Renewable resources may be divided into fund resources (e. g. forests and agricultural land) and flowing resources (e. g. solar radiation and fresh water streams). In many cases, the boundary between the technical and the environmental system is obvious. However, when the life cycle includes forestry, agriculture, emissions to external wastewater systems and landfills, the system boundary needs to be explicitly defined (Finnveden et al. 2009).

Assessing bioenergy systems, geographical boundaries are an important con­sideration. Certain types of biomass feedstock may be limited to certain areas, and productivities may differ from area to area because they are limited by the availability of water, climate, soil or terrain conditions. Furthermore, infrastructure such as electricity production, waste management and transport systems may vary between regions (Von Doderer 2012).

Time boundaries, when defining the goal and scope of the study, are an important aspect of the LCA. Time defines the type of LCA study to be used. Change-oriented LCAs are future bound. They look forward in time, since they are about alternative choices of action. Accounting LCAs ask what environmental impact a product may be made responsible for; hence, they are retrospective (Baumann and Tillman 2004).

Boundaries within the technical system relate, to production capital and person­nel. Whether the environmental impact from production and maintenance of capital goods should be included in an LCA has been debated (Baumann and Tillman

2004) . For accounting LCAs, the guiding principle is that the study should be as complete as possible, and the production and maintenance of capital goods should thus be included. For change-oriented LCAs, whether or not capital goods will be affected by change has to be considered. A topic that is similar to that of capital goods is that of personnel. Processes require personnel, and personnel need food, transportation and so on. However personnel-related environmental impacts are usually not included in an LCA (Baumann and Tillman 2004).

Boundaries within the technical system include those in relation to other products’ life cycles. Sometimes several products (or functions) share the same pro — cess(es). If the environmental load of these processes is to be expressed in relation to a single function, then there is an allocation problem. A detailed discussion of the types of allocation problems, the principles pertaining to allocation, and specific operational allocation methods can be found in Baumann and Tillman (2004).