University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Life cycle assessment of biogas digestate processing technologies

Abstract: Driven by a high increase of large scale biogas plants based on bio waste, agricultural by-products and waste from food industry, there is a rapid structural development of the agricultural holdings in Germany. Particularly in regions with intensive livestock husbandry, this leads to an overprovision of nutrients. New technologies have been introduced during the last years to treat biogas digestate for optimal transport and application conditions. An environmental Life Cycle Assessment (LCA) was carried out in order to compare the environmental impacts and the energy efficiency of seven treatment options of biogas digestate. The treatment options include one conventional digestate management option (storage and application of untreated manure on agricultural land), one stabilization process (composting), three mechanical drying options (belt dryer, drum dryer and solar dryer), one option using thermal vaporization (concentration) and finally one physical–chemical treatment (combination of separation, ultra-filtration, reverse osmosis and ionic exchanger). Primary energy demand (PED), global warming potential (GWP) and acidification potential (AP) were analysed and presented per kg of digestate on the input side of the system as functional unit (fu). Based on the default parameter setting, four scenarios have been defined to analyse the influence of different feedstock, different kinds of energy supply, different emission reductions techniques and different logistic chains on the LCA results. In the overall comparison, solar drying, composting and physical–chemical treatment were identified to be the most suitable options to reduce the use of resources and environmental impacts compared to the conventional digestate management. Belt drying turned out to be the handling process with the highest PED demand, GWP and AP among the compared options. Total PED varies from −0.09 MJ/fu (i.e. savings) in the composting option up to 1.3 MJ/fu in the belt drying option. The GWP was in a range between 0.06 CO 2 eq./fu for solar drying to 0.1 kg CO 2 eq./fu for belt drying. The amount of AP ranged from 2.7 kg SO 2 g eq./fu in composting to 7.1 g SO 2 eq./fu in belt drying. The results indicate that the environmental impact depends largely on nitrogen related emissions from digestate treatment, storage and field application. Another important aspect is the amount and kind of fuel used for heat supply (biogas, natural gas) and the procedure chosen for the allocation among heat and power.

The global technical and economic potential of bioenergy from salt-affected soils

Abstract: This study assesses the extent and location of salt-affected soils worldwide and their current land use and cover as well as the current technical and economic potential of biomass production from forestry plantations on these soils (biosaline forestry). The global extent of salt-affected land amounts to approximately 1.1 Gha, of which 14% is classified as forest, wetlands or (inter)nationally protected areas and is considered unavailable for biomass production because of sustainability concerns. For the remaining salt-affected area, this study finds an average biomass yield of 3.1 oven dry ton ha−1 y−1 and a global technical potential of 56 EJ y−1 (equivalent to 11% of current global primary energy consumption). If agricultural land is also considered unavailable because of sustainability concerns, the technical potential decreases to 42 EJ y−1. The global economic potential of biosaline forestry at production costs of 2€ GJ−1 or less is calculated to be 21 EJ y−1 when including agricultural land and 12 EJ y−1 when excluding agricultural land. At production costs of up to 5€ GJ−1, the global economic potential increases to 53 EJ y−1 when including agricultural land and to 39 EJ y−1 when excluding agricultural land. Biosaline forestry may contribute significantly to energy supply in certain regions, e.g., Africa. Biosaline forestry has numerous additional benefits such as the potential to improve soil, generate income from previously low-productive or unproductive land, and soil carbon sequestration. These are important additional reasons for investigating and investing in biosaline forestry.

Comparison of selection strategies for marker-assisted backcrossing of a gene

Abstract: Marker-assisted selection can accelerate recovery of the recurrent parent genome (RPG) in backcross breeding. In this study, computer simulations were used to compare selection strategies with regard to (i) the proportion of the RPG recovered and (ii) the number of marker data points (MDP) required in a backcross programme designed for introgression of one target allele from a donor line into a recipient line. Simulations were performed using a published maize (Zea mays) genetic map consisting of 80 markers. Selection for the target allele was based on phenotypic evaluation. In comparison with a constant population size across all generations, increasing population sizes from generation BC1 to BC3 reduced the number of required MDP by as much as 50% without affecting the proportion of the RPG. A four-stage selection approach, emphasizing in the first generations selection for recombinants on the carrier chromosome of the target allele, reduced the required number of MDP by as much as 75% in comparison to a selection index taking into account all markers across the genome. Adopting the above principles for the design of marker-assisted backcross programmes resulted in substantial savings in the number of MDP required.