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When a new crop is being promoted as a pro-poor, like in the case of Jatropha curcas (J. curcas) in Zambian rural communities, it is pertinent to explore factors that might affect its adoption, on not only homogenous groups but also heterogeneous wealth categories. This is because poorer farmers may be reluctant to invest in any untried innovations mainly due to their limited factors of production. Evidence from a household survey of 249 randomly selected farmers in eastern Zambia indicates that some factors that affect the farmers in embracing J. curcas seed production and exchange activities differ according to wealth. While factors related to household labour availability were crucial to involvement in J. curcas collection and exchange activities among poorest farmers, it was gender of the household heads and access to off-farm income that significantly influenced these activities among the well endowed farmers. Results further indicate that the farmers who are relatively well endowed are the ones most likely to benefit more from J. curcas collection and selling activities. Well endowed households harvested more seed from hedges because they have more labour and currently harvesting of seed is not restricted to private hedges. Further evidence show that even with fewer household members, the poorly endowed could be involved in planting of hedges. This is an avenue that can help the poorest farmers especially when property rights over J. curcas hedges are secured.

Torrefaction is a promising biomass upgrading technology as it makes biomass more coal alike and offers benefits in logistics and handling operations. Gasification is an attractive thermochemical conversion technology due to its flexibility in the product gas end-uses. Therefore, it is valuable to investigate whether additional benefits are foreseen when torrefaction is coupled with gasification. Therefore, two commercial torrefied wood fuels and their parent materials are gasified at 800–850 °C under atmospheric steam-oxygen circulating fluidized bed gasification conditions and magnesite as bed material. The torrefied feedstocks consisted of wood residues torrefied by Topell at 250 °C (Topell black), and mixed wood and wood residues torrefied by Torrcoal at 300 °C (Torrcoal black). The gasification results show that torrefaction resulted in an increased gas quality, as it yielded higher H2 and CO contents, a decrease of the CO2 content, increased gas yield and a significant decrease of the total tar content for both feedstocks. For the Torrcoal samples, torrefaction resulted in a decrease in the carbon conversion efficiency (CCE). In addition, the cold gas efficiency (CGE) remained approximately the same due to the increase in the H2 and CO contents. The Topell samples showed an increase in the CCE and CGE upon torrefaction, but this could be attributed to a significant grinding in the screw feeder. It is generally concluded that both torrefied fuels may offer benefits as a feedstock for steam-oxygen blown circulating fluidized bed gasification, in particular in terms of gas quality and yield.

Fuel pretreatment methods have attracted attention due global warming concerns. However, these methods impact the combustion and emission behaviors of pretreated fuels, and variations in fuel characteristics influence the formation of NO x during combustion. We investigated the impact of different pretreatment methods (torrefaction and ashless process) on combustion and NOx emission characteristics. Two biomass fuels, i.e., woody ( pitch pine sawdust ( PSD)) and herbaceous (Kenaf), and their pretreated fuels were subject to combustion analysis. The fundamental properties and structural pore characteristics as well as unburned carbon (UBC) and NO x emissions following combustion tests, with both raw and pretreated biomasses, were investigated. The results show torrefaction of both fuels improves the fuel ratio (FR), whereas the ashless process reduces the FR. For both fuels, torrefaction increased the fuel-N by approximately 30%–50%, whereas the ashless process decreased fuel-N. In fixed conditions, the combustion index (S) indicates the ashless process provides greater reactivity for both fuels. Upon torrefaction, S is higher for the PSD samples but lower for the Kenaf samples. In entrained conditions, the UBC for both samples decreased after the ashless process, but increased following torrefaction of Kenaf, which corresponds to the fuel ratios. The ashless process resulted in lower NOx emissions, whereas torrefaction resulted in a different tendency due to variations in N-compounds and fuel volatility for each fuel. These results indicate that the combustion and NOx emissions from different pretreatments are closely linked to characteristics of devolatilization and pore distribution in a fuel.

Abstract This work provides details of an activity undertaken to determine the relevant properties of Croton megalocarpus seeds as a source of vegetable oil and its prospects as a non-food crop source of biodiesel. C. megalocarpus is a tree indigenous to East Africa which grows up to a height of 35–40 m and produces seeds which contain 40–45% oil on a mass basis. The seeds were examined and properties determined that relate to their transport and storage/handling characteristics. Oil was extracted mechanically from the seeds using a hydraulic press and chemically from the pressing residue using petroleum ether. The combustion quality of the extracted crude vegetable oil such as the gross calorific value, carbon, hydrogen and oxygen content and ash content were then determined. This study indicates that the oil from the C. megalocarpus tree has a strong potential as a source of biodiesel.

The thermo-chemical conversion of green microalgae Chlamydomonas reinhardtii wild type (CCAP 11/32C), its cell wall deficient mutant C. reinhardtii CW15 (CCAP 11/32CW15) and Chlorella vulgaris (CCAP 211/11B) as well as their proteins and lipids was studied under conditions of intermediate pyrolysis. The microalgae were characterised for ultimate and gross chemical composition, lipid composition and extracted products were analysed by Thermogravimetric analysis (TG/DTG) and Pyrolysis-gaschromatography/mass-spectrometry (Py-GC/MS). Proteins accounted for almost 50% and lipids 16-22 % of dry weight of cells with little difference in the lipid compositions between the C. reinhardtii wild type and the cell wall mutant. During TGA analysis, each biomass exhibited three stages of decomposition, namely dehydration, devolatilization and decomposition of carbonaceous solids. Py-GC/MS analysis revealed significant protein derived compounds from all algae including toluene, phenol, 4-methylphenol, 1H-indole, 1H-indole-3methyl. Lipid pyrolysis products derived from C. reinhardtii wild type and C. reinhardtii CW15 were almost identical and reflected the close similarity of the fatty acid profiles of both strains. Major products identified were phytol and phytol derivatives formed from the terpenoid chain of chlorophyll, benzoic acid alkyl ester derivative, benzenedicarboxylic acid alkyl ester derivative and squalene. In addition, octadecanoic acid octyl ester, hexadecanoic acid methyl ester and hydrocarbons including heptadecane, 1-nonadecene and heneicosane were detected from C. vulgaris pyrolysed lipids. These results contrast sharply with the types of pyrolytic products obtained from terrestrial lignocellulosic feedstocks and reveal that intermediate pyrolysis of algal biomass generates a range of useful products with wide ranging applications including bio fuels.

Abstract Twelve species of the subgenus Symphyomyrtus and seven of the subgenus Monocalyptus were evaluated for biomass production in small plots under a short rotation forestry regime. The trees were planted at a stocking density equivalent to 2200 stems/ha, and harvested after 3 years. The growth and yield were monitored by measuring the percentage tree survival, stump diameter (mm), tree height (m), and dry weight which was used to determine the comparable biomass yields of the different species. Coppice regrowth was subsequently monitored and is reported elsewhere. The means of tree stump diameter, height and dry weight varied with species. Tree dry weights from the plots with zero mortality ranged from 18.9 kg for E. rodwayii to 21.1 kg for E. brookerana of the Symphyomyrtus subgenus, and from 13.1 kg for E. elata to 15.5 kg for E. nitida for the Monocalyptus subgenus. Biomass yields from the plots with 100% survival varied between 9.6 and 15.5 oven dry tonnes per hectare per year. Overall, species belonging to the Symphyomyrtus subgenus had relatively higher stump diameters, heights, dry weights, and consequently higher yields, than those belonging to the Monocalyptus subgenus. Although the survival rates, growth and yields of the different species showed variations after 3 years, the results were considered to be indicative only for the local region. They were inadequate for making commercial decisions on the choice of species for SRF schemes for biomass production over a wide range of soils and climates. Nevertheless the most outstanding species identified would be worthy of further consideration for any specific site with a temperate climate.

Abstract Mechanisation of sugarcane harvesting is growing rapidly in Southern Brazil where nearly 80% of Brazil’s crop is cultivated. Currently a maximum of 20% of the cane is mechanically harvested and the proportion is expected to rise to about 50% by 2005. However, most of the cane is burned prior to harvesting and less than 2% is harvested green. Issues such as topography, crop cultivation and management methods, labour costs, machine performance, environmental legislation and markets for sugarcane residues will influence the increase in mechanical harvesting of burned or green cane. This paper discusses the prospects for green cane harvesting technology, with emphasis on Southern Brazil, and compares harvesting technologies which are being commercialised today. The paper also addresses the recovery of cane residues (dry and green tops and leaves) and comments on their possible use and commercialisation, particularly for electricity generation.