CH4 Losses Research Articles

Unimolecular Reactions of Ionized Alkanes: Theoretical Study of the Potential Energy Surface for CH3.bul. and CH4 Losses from Ionized Butane and Isobutane

Unimolecular Reactions of Ionized Alkanes: Theoretical Study of the Potential Energy Surface for CH3.bul. and CH4 Losses from Ionized Butane and Isobutane

Methane Production in Goats Given Diets Based on Lucerne hay and Barley

An analysis of data from 102 energy balance trials carried out with Granadina goats, 32 with castrated males and 70 with lactating females, was made with the aim of establishing relationships between methane production and some nutritive attributes of the diet. The diets were based on pelleted lucerne (Medicago sativa) hay and barley and differed widely in the amounts and proportions of their ingredients. Methane production was measured by open-circuit respirometry. The between-animal variation in CH4 production was found to be +/- 8%. In absolute terms, CH4 production increased on increasing the intake of energy. The CH4 loss was 6.56 or 9.75 kJ/100 kJ of gross energy or digestible energy intake, respectively. The prediction of the CH4 production was best described from knowledge of the amounts of the "in vitro" digestible fractions (g/d) of both the neutral-detergent solubles (DNDS) and the neutral-detergent fibre (DNDF), according to the equation CH4 = 2.24 + 0.0299 DNDS + 0.0889 DNDF. The regression was highly significant and the residual standard deviation +/- 6.63 or +/- 20% of the mean. It was also found that on increasing the feeding level by one multiple of maintenance there was a reduction in CH4 losses of 1.51 kJ or 2.19 kJ/100 kJ of gross energy or digestible energy intake, respectively. The CH4 production (kJ/100 kJ of gross energy intake) was also related to the apparent digestibility of energy (D, %) determined at the level of nutrition close to maintenance. The equation was CH4 = -2.58 + 0.151 D. The regression was highly significant statistically.

Heat Increment of Acetate and Corn and Effects of Casein Infusions with Growing Lambs

The heat increment of a corn basal diet and ruminally infused acetate both with and without abomasally supplied casein was measured in two consecutive 4 × 4 Latin square total energy balance experiments with young lambs. Heat production was measured by open circuit indirect calorimetry. The increment of metabolizable energy (ME) resulting from the infusion of 400 to 500 kcal of acetate (0.25 Na acetate, 0.75 acetic acid) was utilized with an efficiency of 67.3 ± 5.1%, when infused with a corn basal diet fed at either 1.1 or 2.1 times the maintenance intake level. This was higher than the ME utilization of the basal diet for tissue deposition above maintenance which averaged 57.8 ± 3.2%. Acetate infusions significantly depressed CH4 losses (P < 0.01) but had no effect on other parameters of energy digestibility or metabolizability. Although infusion of 15 or 45 g of casein plus 2% methionine into the abomasum doubled nitrogen retention, it had no effect on the heat increment of either acetate or the basal diet.

New pendulum experiments

Effective and economical carbon dioxide-methane separation (CO2/CH4) is highly desirable in several industries such as sweetening natural gases and renewable natural gas (RNG) from biogas and landfills. Among the different separation technologies, membrane separation has been shown to have lower cost of production and lower CH4 losses. In this study, Zeolitic Imidazole Frameworks (ZIF-8) crystals with sizes varying from 45 nm to 450 nm were synthesized and incorporated in the polymer of intrinsic microporosity, PIM-1, to form mixed matrix membranes (MMMs). The structure, morphology, and physicochemical properties of the MMMs were characterized by 1H NMR, FTIR, XRD, TGA, and SEM. ZIF-8 crystal size was controlled using the concentration of sodium formate. The influence of the ZIF-8 crystal size on MMMs was studied by sorption, gas permeability, and aging of the membranes. The MMMs with ZIF-8 crystals of 120 nm particle diameter yielded the greatest improvement in gas transport properties; the CO2/CH4 selectivity-CO2 permeability was 11.4 and 9700 Barrer compared to PIM-1 with 6.4 and 9300 Barrer respectively. The former is near the Robeson 2008 upper bound, while PIM-1 is on the 1991 upper bound. After 40 days of aging, selectivity increased and permeability decreased; the changes were parallel to the Robeson upper bounds indicating increased polymer packing and diffusivity selectivity.