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Abstract Continuous bio-methanization of an energy crop, namely the beet silage, was investigated in this laboratory-scale work as mono-substrate, using a mesophilic biogas digester controlled by a fuzzy logic control (FLC) technique and without using any supplementing or buffering agent, despite the low pH of the substrate around 3.80. The temperature, pH, redox potential (ORP), daily biogas production and composition of digester biogas were continuously measured online. During the operation, the hydraulic retention time (HRT) varied between 24.8 and 9 days, as the organic loading rate (OLR) ranged from 2.6 to 4.7 g L −1 d −1 . The average pH, specific gas production rate (spec. GPR) and volumetric gas production rate (vol. GPR) were determined to be 7.12, 0.31 L g VS −1 d −1 and 1.084 L L −1 d −1 , respectively. The average methane (CH 4 ) content of digester biogas was about 56%. The FLC technique, which was developed at HAW Hamburg for anaerobic conversion of acidic energy crops to methane, determined the daily feeding volume (∼ OLR/HRT) for the biogas digester, depending on the feedback from online pH and methane measurements, and on the calculation of the spec. GPR. The spec. GPR was calculated by the corrected daily biogas production. Through online monitoring of pH, biogas production rate and composition, and by use of the FLC technique, the acidic beet silage could continuously be converted to biogas, without using manure or any other kind of buffering or supplementing agent(s). The lab-scale anaerobic biogas digester performed stable and safe, without encountering any problems of instability, as indicated by an adequate amount of buffering capacity, a VFA content below 0.5 g L −1 and a neutral pH range throughout the study.

Abstract Life cycle inventory models of greenhouse gas emissions from biofuel production have become tightly integrated into government mandates and other policies to encourage biofuel production. Current models do not include life cycle impacts of biomass storage or reflect current literature on emissions from soil and biomass decomposition. In this study, the GREET model framework was used to determine net greenhouse gas emissions during ethanol production from corn and switchgrass via three biomass storage systems: wet ensiling of whole corn, and indoor and outdoor dry bale storage of corn stover and switchgrass. Dry matter losses during storage were estimated from the literature and used to modify GREET inventory analysis. Results showed that biomass stability is a key parameter affecting fuel production per farmed hectare and life cycle greenhouse gas emissions. Corn silage may generate 5358 L/ha of ethanol at 26.5 g CO2 eq/MJ, relative to 5654 L/ha at 52.3 g CO2 eq/MJ from combined corn stover and conventional grain corn ethanol production, or 3919 L/ha at 21.3 g CO2 eq/MJ from switchgrass. Dry matter losses can increase net emissions by 3–25% (ensiling), 5–53% (bales outdoors), or 1–12% (bales indoors), decreasing the net GHG reduction of ethanol over gasoline by up to 10.9%. Greater understanding of biomass storage losses and greenhouse gas fluxes during storage is necessary to accurately assess biomass storage options to ensure that the design of biomass supply logistics systems meet GHG reduction mandates for biofuel production.

Abstract Limited information is available regarding biomass production potential of long-term (>5- yr-old) switchgrass (Panicum virgatum L.) stands. Variables of interest in biomass production systems include cultivar selection, site/environment effects, and the impacts of fertility and harvest management on productivity and stand life. We studied biomass production of two upland and two lowland cultivars under two different managements at eight sites in the upper southeastern USA during 1999–2001. (Sites had been planted in 1992 and continuously managed for biomass production.) Switchgrass plots under lower-input management received 50 kg N ha−1 yr−1 and were harvested once, at the end of the season. Plots under higher-input management received 100 kg N ha−1 (in two applications) and were harvested twice, in midsummer and at the end of the season. Management effects on yield, N removal, and stand density were evaluated. Annual biomass production across years, sites, cultivars, and managements averaged 14.2 Mg ha−1. Across years and sites, a large (28%) yield response to increased inputs was observed for upland cultivars; but the potential value of higher-input management for lowland cultivars was masked overall by large site×management interactions. Nitrogen removal was greater under the higher-input system largely due to greater N concentrations in the midsummer harvests. Management recommendations (cultivar, fertilization, and harvest frequency), ideally, should be site and cultivar dependent, given the variable responses reported here.

Abstract Bioenergy crops are one of the renewable energy options available to decarbonise the energy sector in Scotland and help to achieve the overall planned target of 80% reduction in greenhouse gas (GHG) emissions by 2050. A process-based model for poplar and willow developed for simulating the effect of different environmental and management options on growth and biomass yield was used to estimate the GHG abatement potential (GHG-AP) under different crop management options in Scotland. The model results of annual wood yield did not show a strong relation with any of the environmental factors except that of initial soil organic carbon (SOC) content. Increasing plant density and decreasing harvest frequency increased GHG-AP. Application of N-fertilizers at a rate of 50–100 kg N ha−1 resulted in the buildup of carbon in soils with less than 180 Mg C ha−1. However, in soils with greater SOC contents, annual emissions resulting from N fertilizer application were greater than the carbon saving through marginal increases in wood yield and SOC changes. The best management scenario in terms of economic and environmental objectives depends on identifying an optimum plant density based on the site specific conditions with a fertilizer application of 20–100 kg ha−1 y−1 and a five year harvest interval. Even under the best economic scenarios, SRC willow and poplar have a GHG-AP ranging from 9.9 to 11.6 and 8.8–10.0 Mg CO2 eq. ha−1 y−1, respectively. Under the best environmental scenarios this range increases to 10.5- 13.2 and 9–11.1 Mg CO2 eq. ha−1 y−1 for willow and poplar, respectively.

Miscanthus biomass yield can be limited by poor rhizome establishment and this is linked to rhizome age and storage conditions prior to planting. To avoid poor establishment, best practice recommends field planting directly after rhizome division. Operations avoiding rhizome storage, and utilising favourable climatic conditions at planting, may be climatologically and logistically challenging when large areas are planted at high rhizome densities. Our aim is to evaluate storage regimes to maintain rhizome viability and maximise establishment when planted under optimal conditions. To achieve this we have compared differences in site pre-planting management (level of soil cultivation) strategies, along with post-planting treatments (irrigation and soil mulching with compost), against differences in storage regime (temperature) and duration. The results from a rhizome establishment bioassay showed viability at lifting in early March was high, while cold storage of rhizomes had no negative influence on viability and growth. There were no negative impacts of storage temperature on rhizome mineral or carbohydrate concentrations. Increases in air temperature enhanced rhizome and culm final biomass and rate of establishment. Application of irrigation, or compost mulch, to field rhizome plantings improved establishment increasing soil moisture levels in early May through August. In conclusion, cold storage of rhizomes is achievable and effective in maintaining rhizome viability and can be used to extend the planting time. Soil moisture and application of supplementary irrigation was important during establishment. Also important was the avoidance of weed competition. Achieving the most appropriate conditions for optimal establishment will be critical in regions where spring/summer rainfall is restrictive.

Abstract With the shift from petroleum-based to biomass-based economies, global biomass demand and trade is growing. This trend could become a threat to food security. Though rising concerns about sustainability aspects have led to the development of voluntary certification standards to ensure that biomass is sustainably produced, food security aspects are hardly addressed as practical criteria and indicators lack. The research objective is to identify how the Human Right to adequate Food (RtaF), which is applicable in over 100 countries, can be ensured in local biomass production and in certification systems in food insecure regions. We aim to first develop a suitable conceptual framework to integrate the RtaF in biomass production, processing and trade and derive guidance for the choice the criteria. Second, we identify appropriate criteria to ensure that the RtaF is not violated by certified biomass operators based on a comprehensive literature review, stakeholder workshops and expert interviews with certification bodies, standard initiatives, NGOs, ministries, scientists and enterprises. The conceptual framework is based on the UN “Voluntary Guidelines to Support the Progressive Realization of the RtaF in the Context of National Food Security” and the four dimensions of food security. Based on this framework, we developed the rights-based food security principle. We selected 45 criteria that ensure that the RtaF is not adversely affected by certified biomass production of companies and farmers. The suggested criteria are applicable to all biomass types and uses and serve as a best-practice set to complement existing sustainability standards for biomass.

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.

Abstract Weyerhaeuser Company is committed to being a responsible steward of the environmental quality and economic value of the forests we manage. Weyerhaeuser's regional Forest Councils have developed specific resource strategies for forest products, water quality, wildlife habitat, soil productivity and aesthetics. The sustainable site productivity or soil productivity strategy is as follows: “We protect soil stability and ensure long-term soil productivity by: (1) using equipment and practices appropriate to the soil, topography and weather to minimize erosion and harmful soil disturbance, and (2) using forestry practices and technology to retain organic matter and soil nutrients.” The elements of the Weyerhaeuser reliable processes used to achieve this strategy in the Northwest, U.S.A. include (1) a research database; (2) common goals and standards leading to management guidelines; (3) education, training and teaming across the organization; (4) implementation of Best Management Practices (BMPs); (5) monitoring of performance and (6) adaptive experimentation. This is not a static process—continuous improvement is a design element in the process. Guidelines and BMPs have been developed to minimize detrimental soil disturbance. This was accomplished by having (1) a strategic database on soil disturbance impacts; (2) a classification system that describes soil disturbance classes; (3) a soil operability risk rating system that rates soils on their susceptibility to compaction and puddling; and (4) a close working relationship between R and D and operations to develop BMPs. Steps are being taken to develop organic matter management guides for various soil groups and a soil nutrient risk-rating system. These combined with fertilizer guides will lead to practices that conserve and strive to maintain organic matter and soil nutrients. Education and training of employees is an important step in implementing the guides and BMPs. Operational practices are monitored to assess performance against specified standards. Identification of knowledge gaps lead to additional research and operational adaptive trials. Based on new research information, operational experiences and monitoring feedback. BMPs will be continuously improved to meet Weyerhaeuser's sustainable site productivity strategy.

Perennial energy crop development is just starting in Poland and there are great expectations on this sector to make a substantial contribution to the achievement of renewable energy targets defined in the European Union (EU) directive 28/2009/EC. Insights into the economics of energy crop production may lead to a better understanding of the dynamics of developments in the field. This work addresses current and future economics of willow, Miscanthus and triticale (a whole crop) production for energy use in Poland. The economics of energy crops is set next to that of common cereal production for grain. Potential cost reductions of energy crops in the future are investigated with regard to the hypothetical impact of scale effect, as well as the combined effect of scale and technology developments. Results indicate that for the assumed biomass prices applied, willow is profitable while Miscanthus and triticale generate loss. The volatility of cereal market prices is found to significantly affect the competitiveness of energy crops compared to grain production. Willow and Miscanthus are produced with lower costs compared to triticale. Furthermore, the economics of perennials are less susceptible to changes in agricultural inputs prices compared to annual crops. For the first farmers to cultivate energy crops, the costs are high, however, there are large opportunities for cost reduction due to the economics of scale and technology developments. With the expected increase in biomass market demand and biomass prices, energy crops should be profitably produced in the future. (C) 2011 Elsevier Ltd. All rights reserved. (Less)