John Morken

Effects of steam explosion and co-digestion in the methane production from Salix by mesophilic batch assays

Salix that was steam exploded at different conditions of temperature and time was anaerobically digested in a series of batch tests. Steam explosion proved to be favorable to increase the methane yields up to 50%, with best results obtained for temperatures starting at 210 °C. Batch studies for mixtures of cow manure and steam exploded Salix were performed, with C/N ratios varying from 31 to 56, related to volatile solids (VS) contents from 20 up to 80% of each of the substrates. Methane yields reached 230 mL CH(4)/g VS for the mixtures containing 30% and 40% VS of Salix over the total mixtures VS content (35 and 39 C/N ratio, respectively). A fraction up to 40% in VS from pre-treated Salix provided good methane yields with a faster digestion process.

Direct Ground Injection of livestock waste slurry to avoid ammonia emission

The aim of the project was to improve the slurry injection techniques for injecting animal waste slurries into the soil under Norwegian conditions. A new slurry application technique for grassland was therefore developed, by adapting well known methods of injecting a fluid into a solid or porous material. The injection nozzles had a diameter of 13 mm, and the liquid pressure in the nozzles was between five and eight bar, which was sufficient for the slurry to be injected 5 to 10 cm into the ground. The depth of the injection depended on the soil type and on the slurry pressure. Ammonia emission was reduced as compared with application through ordinary broadcasting, and with band spreading. The emission was also reduced if water was added to the slurry, or if the slurry solids were separated from the liquid before application.

Ammonia emissions from agriculture

Holger Kirchmann1, Martti Esala2, John Morken3, Martin Ferm4, Wim Bussink5, Jan Gustavsson6 & Christine Jakobsson7 1Department of Soil Sciences, Swedish University of Agricultural Sciences, Box 7104, S-750 07 Uppsala, Sweden; 2Institute of Crop and Soil Science, Agricultural Research Centre of Finland, Fin-31600 Jokioinen, Finland; 3Department of Agricultural Engineering, The Agricultural University of Oslo, Box 5065, N-1432 EAs Norway; 4Swedish Environmental Research Institute, Box 47086, S402 58 Gothenburg, Sweden; 5Nutrient Management Institute, Runderweg 6, 8219 PK Lelystad, The Netherlands; 6Swedish Board of Agriculture, S-551 82 Jonkoping, Sweden; 7Swedish Board of Agriculture, S-751 86 Uppsala, Sweden

The BioValueChain model: a Norwegian model for calculating environmental impacts of biogas value chains

PurposeThe BioValueChain model facilitates the calculation of environmental impacts throughout the value chain for production of biogas from organic waste and manure in Norway. This paper describes the methodology of the model, presents the results based on general data and performs a sensitivity analysis for the input data.MethodsThe model is based on life cycle assessment methodology and defines the boundaries of the system and a set of default parameter values which can easily be changed to obtain relevant results for a specific region or a specific biogas plant.Results and discussionThe general results from application of the model show that the application of biogas and digestate, including the assumption regarding which products are substituted, has significance for the results. The sensitivity analysis reveals that results for global warming potential (GWP) appear to be less sensitive for the different parameter values than the other environmental indicators. Increased biogas production from source separated organic household waste and manure from cattle and pigs appears to be an appropriate greenhouse gases (GHG) mitigation measure for Norwegian conditions if the biogas substitutes fossil fuels and if the digestate substitutes mineral fertiliser.ConclusionsThe results underline the need for the use of specific data, especially for transport distances, biogas potential and efficiency of biogas plant. Furthermore, in order to decrease the uncertainty of the results, more research is required into ways of modelling and quantifying direct emissions from the storage and application of manure and digestate on land.

Methane production and energy evaluation of a farm scaled biogas plant in cold climate area.

The aim of this study was to investigate the specific methane production and the energy balance at a small farm scaled mesophilic biogas plant in a cold climate area. The main substrate was dairy cow slurry. Fish silage was used as co-substrate for two of the three test periods. Energy production, substrate volumes and thermal and electric energy consumption was monitored. Methane production depended mainly on type and amount of substrates, while energy consumption depended mainly on the ambient temperature. During summer the main thermal energy consumption was caused by heating of new substrates, while covering for thermal energy losses from digester and pipes required most thermal energy during winter. Fish silage gave a total energy production of 1623 k Wh/m(3), while the dairy cow slurry produced 79 k Wh/m(3) slurry. Total energy demand at the plant varied between 26.9% and 88.2% of the energy produced.