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Two studies conducted in Guadeloupe (West Indies) and Réunion (Indian Ocean) islands were designed to investigate the benefits of producing sugarcane as an energy crop and to assess the influence of agroclimatic factors on energy efficiency, respectively. In this context, it is essential to know the low heating value of the dry above-ground biomass (LHVd, MJ/kg) and its energy yield (EY, MJ/m2) in order to select the best varieties and set up a payment method for growers. Eighteen Poaceae (sugarcane and Erianthus) cultivars were compared under wet tropical environmental conditions in Guadeloupe. Three sugarcane cultivars were studied in four contrasting environments in Réunion. The partition sampling and biomass measurement procedures were identical at both locations. Low heating value (LHV) predictions were achieved using near-infrared reflectance spectroscopy (NIRS) after specific calibration (Guadeloupe), or arithmetically after lignocellulosic compound prediction (Réunion). In both studies, LHV variability was very low and slightly dependent on the site, cultivar and above-ground biomass components (millable stalks and tops, and green and dead leaves). Considering the overall dry above-ground biomass (DAB, kg/m2), the LHVd was calculated by averaging 159 samples (mean 16.65 MJ/kg) in Guadeloupe and 315 samples (mean 16.45 MJ/kg) for Réunion. An excellent linear relationship between the DAB and its EY, regardless of cultivar, age and environment, was found (n = 474 and R² = 0.99). Sugarcane energy content assessment could thus be simplified by measuring the DAB, while enabling development of a faster method of payment for growers based on the DAB measurement and the correlation between DAB and EY. Finally, the findings of this study should allow growers to rapidly determine the commercial value of their sugarcane crops, and also enable purchasers to assess the amount of recoverable energy. (Résumé d'auteur)

Abstract In the past 10 years, 90% of cassava starch factories in Thailand have switched from fuel oil to renewable biogas, to cover part of their energy needs. The environmental benefits of switching to biogas have not been assessed quantitatively. To alleviate this, this study assessed 100-year greenhouse gas (GHG) emissions, or carbon footprint (CF), of cassava starch production for four factories in Thailand. Key results demonstrate that biogas reduces the carbon footprint of the Thai cassava starch industry as a whole by 0.9–1.0 million tons CO2eq/year, and highlight methodological precautions to collect LCI data and allocate GHG emissions between co-products with high moisture contents. The system boundaries included farm stage (production of cassava roots), transportation to factory and processing into native starch. The functional unit (FU) was one ton of native cassava starch at 13% water content. Biogas produced from the factory wastewater (95–200 m3/FU) was the main source of thermal energy for starch drying, and for on-site electricity production when excess biogas was available. The total CF of cassava starch was in the range 609–966 kg CO2eq/FU. Agricultural production contributed 60% of the carbon footprint, mainly from the use of nitrogen fertilizers. GHG emissions of root production varied widely due to (1) the diversity of farming practices even within a small radius (50 km), and (2) different agricultural yields in different regions. The contribution of the factory stage to the carbon footprint depended on the use of electricity, biogas and other fuels, ranging from 217 to 342 kg CO2eq/FU. Allocation rules such as wet weight or dry weight basis allocations affected the results markedly.

Abstract In many African countries, the upswing in oil prices is one factor that favours the adoption and implementation of a national biofuel policy. This trend has a major impact on state budgets and domestic trade balances, while also limiting the access of rural inhabitants to modern energy services. Contribution of biofuels in stabilizing the energy sector, influences ongoing negotiations on the global dynamics of climate change, the reduction in greenhouse gas (GHG) emissions and sustainable development. The question of biofuels as an alternative energy thus depends on international, national and local considerations. Biofuels represent opportunities, e.g., energy independence and security, new national income and employment sources, as well as potential food security problems. African policy makers therefore need to make the right choices to guide the development of biofuel production and use. This article aims to support the development of a biofuel policy by reviewing the latest technical, economic, environmental and social knowledge so as to be able to evaluate the potential and limits of biofuels in Burkina Faso.

Palm heart is an important non-timber forest product obtained from various palm species in tropical forests. We studied the effect of four decades of palm heart extraction from the clonal palm Euterpe oleracea at the southern Pacific coast of Colombia. We monitored populations that had been subject to a range of harvest intensities and used measured vital rates (survival, growth, sexual and clonal reproduction) to construct population matrix models. We then used these models to simulate several harvest scenarios and to project the population dynamics for the next 50 years. Our projections suggest that the currently implemented intensive harvest regimes - which involve up to four harvests per year - result in dramatic demographic changes, primarily affecting seedlings and adults. In addition, current harvest regimes affect the future supply of palm heart, which is projected to drop sharply during the first years following harvest and fails to recover unless a number of stems are spared. Our simulations indicate that the most sustainable scenarios involve annual harvest between 50% and 75% of all harvestable stems, without any removal of small shoots from the clumps. Implementation of this regime must be accompanied by other management practices, including planning harvestable areas, marking the stems to be cut during subsequent harvests, assigning harvesters to specific areas, and leaving harvest residues as mulch around clumps. The degradation of populations of E. oleracea directly affects livelihoods of local people, by reducing cash income from palm heart sales and by reducing availability of palm fruits, a locally important food resource. (C) 2014 Elsevier B.V. All rights reserved.

In Guadeloupe (French West Indies), studies (REBECCA project) were conducted to investigate the benefit of producing sugarcane as a dedicated energy feedstock using the entire dry shoot biomass (DSB).After a first selection from among 36 Poaceae, 10 sugarcane varieties were tested and compared to R579, the best local commercial sugarcane (CSC), (three replications, 40-m2 plots, volcanic soil) over 3 years in wet tropical conditions. Wet and dry biomasses as well as energy yield (EY, MJ/m2) were measured on stalks, tops, green and dead leaves. Two varieties (W181456, W179460) from WICSBS (Barbados) were very efficient and well-adapted. The DSB was 81 t/ ha/year and the low heating value of this DSB was 133 MJ/m2 after a 12-month cropping cycle. Dry/wet DSB was 0.36 (0.43 without tops). These varieties were cropped using the same practices as local CSC, but yields were higher: +33% for stalks and +71% for DSB). These two varieties could be considered as good feedstock for a biomass power plant but they need to be dried before being used. Growers, purchasers and agronomists are now informed of local potential yield and quality of the tested varieties.(Résumé d'auteur)

Food supply chains (FSCs) not only need to be competitive, but increasingly face scarce resources and societal pressure for sustainable development. This paper assesses the economic, social, and environmental sustainability of five different FSCs that are all competing for the same primary product. We used the value chain methodology for the economic sustainability, life cycle assessment for the analysis of environmental sustainability, and a scoring approach for social sustainability. We applied these methodologies to five FSCs competing for mangoes in Burkina Faso: 1) the FSC of fresh mangoes exported (by boat or by plane) to the European Union, 2) the FSC of fresh mangoes exported to continental Africa, 3) the FSC of dried mangoes exported to Europe, 4) the FSC of mango juice and puree, and 5), the FSC of fresh mangoes consumed in Burkina Faso. For each FSC, we considered: 1) the added value per kilogramme; 2) male and female employment; 3) the contribution to the national economy; 4) working conditions; 5) the contribution to household food and nutritional security; 6) damage to human health per added value, 7) damage to ecosystems per added value, and 8) increased resource scarcity per added value. None of the FSCs obtained a perfect score. The domestic FSC had the best sustainability indicators and the African FSC distributed the highest share of added value to farmers. The number of middlemen, the operating costs, the trade value of the mangoes, and bargaining power, are the main factors affecting the distribution of the added value. The informal sector is a major factor that affects the social assessment through access to land and to most social rights. Distance and transport technology are the main factors that affect the environmental sustainability. Our results will help improve benchmarking of FSCs in a sustainability framework, targeting of private funding investment, and policy support for sustainable development.

Toilet compost (TC) and human urine are among natural fertilizers, which raise interest due to their double advantages to combine sanitation and nutrient recovery. However, combination of urine and TC is not so spread probably because the best ratio (urine/TC) is still an issue and urine effect on soil chemical properties remains poorly documented. This study aims to determine the best ratio of urine and TC in okra cultivation, by targeting higher fertilization effect combined with lower impact on soil chemical properties. Based on Nitrogen requirement of okra, seven treatments were compared: (T0) no fertilizer, (T1) chemical fertilizer (NPK: 14-23-14), (T2) 100% urine, (T3) 100% TC, (T4) ratio of 75% urine+25% TC, (T5) 50% urine+50% TC and (T6) 25% urine+75% TC. Results indicated that T4 (75% urine+25% TC) gave the highest plant height and yield. In contrast, T2 (100% urine) gave the lowest results among all treatments, indicating toxicity effects on plant growth and associated final yield. Such toxicity is confirmed by soil chemical properties at T2 with soil acidification and significant increase in soil salinity. In contrast, application of urine together with TC mitigates soil acidification and salinity, highlighting the efficiency of urine and TC combination on soil chemical properties. However, further investigation is necessary to refine better urine/TC ratio for okra production.

Abstract Argentina's nuclear reactor fleet provides about 10% of the country's electricity, and it is foreseen to increase nuclear power production in the future. Although most Argentinians accept nuclear power generation, public opinion is not in favor of uranium mining and all uranium needs are presently met by uranium imports at costs above international market prices (both spot and long-term contracts). Argentina also imports considerable amounts of phosphate rock and phosphate fertilizer to supply its agricultural industry. It is well-known that phosphate rocks and phosphate fertilizers can contain elevated amounts of associated uranium that is dissipated on agricultural soils if it is not recovered during fertilizer production. In this work, we estimate the amount of uranium that can be recovered from imported phosphate rock, determine the amount of uranium that could theoretically be recovered from all phosphate fertilizers used in Argentina and discuss potential uranium recovery from identified domestic phosphate rock resources.