INNO Mil-CH4 GHG Emissions from Milk Production

Conference poster PD

Effect of Steam Explosion Pretreatment on the Specific Methane Yield of Miscanthus x giganteus

A highly promising energy crop for biogas production can be Miscanthus x giganteus. It has multiple advantages, which include low soil requirements and the existence of genotypes adapted to dry conditions in comparison to other energy crops. Miscanthus cannot be used in the biogas plant without a pretreatment due to the recalcitrant nature of lignocelluloses. One of the most efficient pretreatment methods for lignocellulosic biomass is steam explosion. This includes heating the biomass at high temperature values, followed by mechanical disruption of the biomass fibres by a rapid pressure drop. The objective of this study is to analyse the effect of the steam explosion pretreatment on the specific biogas and methane production of miscanthus. In addition methane hectare yields are calculated and compared to those of maize. Steam explosion pretreatment was carried out in a laboratory scale facility in Ĺs, Norway. The miscanthus was mixed with water and heated up to the desired temperature. After a defined pretreatment time the pressure in the reaction vessel was reduced rapidly, which caused the liquid water to vaporize immediately. The material was cooled down in a flushing tank and was then stored at 5°C until further analytical procedures. Pretreatment temperatures were 190°C and 210°C; holding times were 5, 10 and 15 minutes. Determination of the specific methane yield was done in triplicate using batch tests according to VDI 4630. The material was inoculated with the liquid fermentation residue of a biogas plant. The produced gas was collected in eudiometers and then analysed for the CH4 and CO2 content

The Effect of Diet and Farm Management on N2O Emissions from Dairy Farms Estimated from Farm Data

The N2O emissions of 21 dairy farms in Germany were evaluated to determine the feasibility of an estimation of emissions from farm data and the effects of the farm management, along with possible mitigation strategies. Emissions due to the application of different fertilisers, manure storage and grazing were calculated based on equations from the IPCC (Intergovernmental Panel of Climate Change) and German emission inventory. The dependence of the N2O emissions on fertiliser type and quantity, cultivated crops and diet composition was assessed via correlation analysis and linear regression. The N2O emissions ranged between 0.11 and 0.29 kg CO2eq per kilogram energy-corrected milk, with on average 60% resulting from fertilisation and less than 30% from fertiliser storage and field applications. The total emissions had a high dependence on the diet composition; in particular, on the grass/maize ratio and the protein content of the animal diet, as well as from the manure management. A linear model for the prediction of the N2O emissions based on the diet composition and the fertilisation reached a predictive power of R2 = 0.89. As a possible mitigation strategy, the substitution of slurry for solid manure would reduce N2O emissions by 40%. Feeding cows maize-based diets instead of grass-based diets could reduce them by 14%