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Tafarte P.,Helmholtz Center for Environmental Research | Das S.,Helmholtz Center for Environmental Research | Eichhorn M.,Helmholtz Center for Environmental Research | Thran D.,Helmholtz Center for Environmental Research | Thran D.,DBFZ German Biomass Research Center

The on-going energy transition in Germany aims at a power system dominated by RES (renewable energy sources) with more than 80% in 2050. The primary contributions are expected to come from inherently vRES (variable renewable energy sources), especially wind and solar power. Under currently insufficient storage capacity and limited flexible RES, alternatives for the integration of increasing shares of vRES are urgently needed.This paper aimed at optimizing feed-in patterns to improve system integration of vRES in central Germany for vRES targets of 50% (2030) and 80% (2050). Numerical optimization for optimal shares of wind and solar was conducted for baseline and advanced technology set-up using minimization of excess energy as an indicator for system integration. Results show that for the 50% vRES target, advanced technology reduced excess energy by up to 53% and optimal shares in capacity include 34% wind and 66% solar. Further, the demand for installed wind capacities could be reduced by as much as 55%. This reduction can translate into lower land demand, thereby supporting sustainability concepts. This article concludes that there is a high potential of system integration of increasing shares of vRES in the near to middle-term, especially by the adoption of advanced technologies. © 2014 Elsevier Ltd. Source

Arthur R.,Koforidua Polytechnic | Glover K.,DBFZ German Biomass Research Center
Bioresource Technology

The palm oil industry experienced significant improvement in its production level from 2002 to 2009 from the established companies, medium scale mills (MSM), small scale and other private holdings (SS and OPH) groups. However, the same cannot be said for treatment of the palm oil mill effluent (POME) produced. The quantity of crude palm oil (CPO) produced in Ghana from 2002 to 2009 and IPCC guidelines for National Greenhouse Gas Inventories, specifically on industrial wastewater were used in this study. During this period about 10 million cubic metres of POME was produced translating into biomethane potential of 38.5 millionm 3 with equivalent of 388.29GWh of energy. A linear growth model developed to predict the equivalent carbon dioxide (CO 2) emissions indicates that if the biomethane is not harnessed then by 2015 the untreated POME could produce 0.58 million tCO 2-eq and is expected to increase to 0.70 million tCO 2-eq by 2020. © 2012 Elsevier Ltd. Source

Ziganshin A.M.,Kazan Federal University | Liebetrau J.,DBFZ German Biomass Research Center | Proter J.,DBFZ German Biomass Research Center | Kleinsteuber S.,Helmholtz Center for Environmental Research
Applied Microbiology and Biotechnology

The influence of the feedstock type on the microbial communities involved in anaerobic digestion was investigated in laboratory-scale biogas reactors fed with different agricultural waste materials. Community composition and dynamics over 2 months of reactors' operation were investigated by amplicon sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Major bacterial taxa belonged to the Clostridia and Bacteroidetes, whereas the archaeal community was dominated by methanogenic archaea of the orders Methanomicrobiales and Methanosarcinales. Correlation analysis revealed that the community composition was mainly influenced by the feedstock type with the exception of a temperature shift from 38 to 55 °C which caused the most pronounced community shifts. Bacterial communities involved in the anaerobic digestion of conventional substrates such as maize silage combined with cattle manure were relatively stable and similar to each other. In contrast, special waste materials such as chicken manure or Jatropha press cake were digested by very distinct and less diverse communities, indicating partial ammonia inhibition or the influence of other inhibiting factors. Anaerobic digestion of chicken manure relied on syntrophic acetate oxidation as the dominant acetate-consuming process due to the inhibition of aceticlastic methanogenesis. Jatropha as substrate led to the enrichment of fiber-degrading specialists belonging to the genera Actinomyces and Fibrobacter. © 2013 Springer-Verlag Berlin Heidelberg. Source

Moller K.,University of Hohenheim | Stinner W.,DBFZ German Biomass Research Center
Nutrient Cycling in Agroecosystems

Organic farming systems are characterized by the strong regulation of the import of nutrients into the farming system to replace nutrient losses via sold products. In the present study mineral nutrient flows and balances of P, K and magnesium (Mg) were analysed for a mixed organic cropping system with dairy husbandry and for a stockless organic farming system. Also the influence of biogas digestion of farmyard residues (stable wastes, crop residues, etc.) as well as the effect of the import of substrates for biogas digestion on plant mineral nutrient uptake and farmgate nutrient balances was analysed. The objectives of the current study were; (1) to study the effects of anaerobic digestion of cattle manure and crop residues on plant mineral nutrient uptake; and (2) to model nutrient flows and balances related to the input of different kind of substrates for biogas digestion at the farmgate. Results indicated that slurry digestion did not influence plant P and K uptake. Import of single allowed substrates for digestion would lead to large imbalances in nutrient inputs compared to withdrawals. Most of the suited substrates for biogas digestion were associated with large K surpluses and insufficient P returns in comparison to mineral nutrient outputs via sold animal and plant products. © 2010 Springer Science+Business Media B.V. Source

Michel J.,DBFZ German Biomass Research Center | Weiske A.,DBFZ German Biomass Research Center | Moller K.,University of Hohenheim
Renewable Agriculture and Food Systems

A life-cycle assessment (LCA) was carried out to compare the environmental performance of different organic cropping systems with and without digestion of slurry and crop residues. The aims of the present study are: (1) to compare the environmental performance of organic farming dairy systems with the currently prevalent animal housing systems [solid farmyard manure (FYM) versus liquid slurry] as the main reference systems; (2) to analyze the effect of the implementation of a biogas digestion system on the consumption of fossil fuels and production of electrical energy; (3) to quantify the effects of the implementation of a biogas digestion system on the environment; and (4) to compare the obtained net energy yields with other means of obtaining energy by using the farmland area. The considered impact categories are greenhouse gas (GHG) balances, acidification, eutrophication and groundwater pollution. LCA results indicated that total emissions in systems based on FYM are much higher than in liquid slurry systems for most of the considered impact categories. The benefits of digestion of stable wastes in comparison with the reference system without digestion are mainly (1) the net reduction of the emissions of GHG and (2) energy recovery from produced biogas, while the disadvantages can be higher emissions of NH3 after spreading. The effects of additional biogas digestion of biomass such as crop residues (e.g., straw of peas and cereals) and cover crops are: (1) an optimization of the N-cycle and therewith higher yields; (2) higher energy production per unit arable land; (3) a further reduction of the GHG balance; but (4) higher N-related environmental burdens like eutrophication and acidification. The offsets of fossil fuel emissions were the largest GHG sink in most of the biogas digestion systems. The inclusion of a biogas plant into organic cropping systems and the use of the available wastes for production of energy largely increased the overall productivity of the farming system and matched very well the basic principles of organic farming such as a high self-sufficiency of the cropping system and reducing as much as possible the environmental impact of farming. Copyright © Cambridge University Press 2010. Source

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