Biogas production: litter from broilers receiving direct-fed microbials and an enzyme blend

ABSTRACT The effect of additives used in the feed of broilers on anaerobic bio-digestion of poultry litter was evaluated. Four diets were used: NC: negative control; DFM: NC + 500 ppm direct-fed microbials (DFM) containing Bacillus subtilis and Bacillus licheniformis; ENZ: diet formulated with an enzyme blend (20 ppm phytase, 200 ppm protease and 200 ppm xylanase); DFM+E: ENZ + DFM. Substrates for the anaerobic bio-digestion were prepared with litter from each treatment, containing 4 % total solids (TS). These were used in 16 continuous bio-digesters with a 2 kg d−1 load, to determine the production and potential biogas production and composition during an 85-day period. Influent and effluent samples were collected for the amounts of TS and volatile solids (VS), fiber fraction (neutral detergent fiber [NDF], acid detergent fiber [ADF] and lignin), nutrients (N, P and K), and total and thermotolerant coliforms to be determined. For all treatments a reduction in the following effluents was observed as follows: TS (49, 48, 48 and 50 %) VS (70, 54, 55 and 62 %) NDF (91, 90, 95 and 96 %) ADF (89, 88, 93 and 94 %) and lignin (80, 76, 89 and 88 %). The efficiency of the treatment for coliforms in bio-digesters was higher than 90 % in the 85-day period in all treatment groups. There was a reduction in biogas and methane production when DFM (5500 and 4000 mL) and DFM + E (5800 and 4100 mL) were used, compared to treatments NC (6300 mL and 4400) and ENZ (6400 and 4500 mL). The potential production of reduced TS and VS was higher in ENZ (1:00 and 1.74 106 mL kg−1) when compared to NC (0.88 and 1:02 106 mL kg−1), DFM (0.80 and 1:40 106 mL kg−1) and DFM + E (0.88 1:25 and 106 mL kg−1). The additives did not affect the percentage of methane production, and all treatments showed values higher than 70 %. Adding enzymes to the diet of broilers influences the litter characteristics and, as a consequence, increases biogas production. The addition of DFM and DFM + E to broiler diets reduced biogas and methane production

Characterisation of long-term voltage stability with variable-speed wind power generation

Voltage stability in general is of paramount importance with increasing penetration levels of variable-speed wind power generators (VSWGs) in power systems. Limited knowledge exists considering the impact of VSWGs on long-term voltage stability (LTVS) of power systems, focusing on doubly fed induction generators and full-converter wind generators. This paper presents the results of a comprehensive study on the impact of VSWGs on LTVS. Integration of wind generators while operating the existing synchronous generators improves the LTVS. However, it is unlikely that power systems will retain all existing synchronous generators operating, with high wind penetration levels. Therefore, this study compares the capability of the synchronous generators and VSWGs on LTVS by considering the dynamic reactive power capabilities. The significance of overload capability of synchronous generators on LTVS is highlighted. It is also illustrated that integrating wind farms at remote and local locations from load centres has distinct impacts on LTVS. Replacement of synchronous generators located in close proximity to load centres has a detrimental effect on LTVS. Furthermore, this study demonstrates the impact of different wind generator loading levels on LTVS. The study outcomes highlight several distinct factors which influence the LTVS of power systems with high wind penetration levels

Investigation of load driven long-term voltage instability phenomenon with wind generation

This paper investigates the impact of doubly fed induction generator (DFIG) based wind power generation on the long-Term voltage stability of a power system having dynamic loads such as induction motors. The investigation was carried out using a test system developed in DIgSILENT Power Factory. A detailed aggregated model of a DFIG wind farm is developed as the main source of wind generation. Three different dynamic load models have been used in the study and the results are presented as three different case studies. This research study has shown that the voltage stability is improved for a network comprised of induction motors, when the DFIG wind power generation is added to the system. However, this conclusion is not valid for all types of dynamic loads. Therefore, detailed studies have to be conducted using accurate aggregate dynamic load models to accurately characterise the voltage stability of a network

Reliability and Failures in Solid State Lighting Systems

Reliability is an essential scientific and technological domain intrinsically linked with system integration. Nowadays, semiconductor industries are confronted with ever-increasing design complexity, dramatically decreasing design margins, increasing chances for and consequences of failures, shortening of product development and qualification time, and increasing difficulties to meet quality, robustness, and reliability requirements. The scientific successes of many micro/nano-related technology developments cannot lead to business success without innovation and breakthroughs in the way that we address reliability through the whole value chain. The aim of reliability is to predict, optimize, and design upfront the reliability of micro/nanoelectronics and systems, an area denoted as “Design for Reliability (DfR)”. While virtual schemes based on numerical simulation are widely used for functional design, they lack a systematic approach when used for reliability assessments. Besides this, lifetime predictions are still based on old standards assuming a constant failure rate behavior. In this chapter, we will present the reliability and failures found in solid-state lighting systems. It includes both degradation and catastrophic failure modes from observation toward a full description of its mechanism obtained by extensive use of acceleration tests using knowledge-based qualification methods.Electronic Components, Technology and MaterialsMechanical, Maritime and Materials Engineerin

Reliability and Failures in Solid State Lighting Systems

Reliability is an essential scientific and technological domain intrinsically linked with system integration. Nowadays, semiconductor industries are confronted with ever-increasing design complexity, dramatically decreasing design margins, increasing chances for and consequences of failures, shortening of product development and qualification time, and increasing difficulties to meet quality, robustness, and reliability requirements. The scientific successes of many micro/nano-related technology developments cannot lead to business success without innovation and breakthroughs in the way that we address reliability through the whole value chain. The aim of reliability is to predict, optimize, and design upfront the reliability of micro/nanoelectronics and systems, an area denoted as “Design for Reliability (DfR)”. While virtual schemes based on numerical simulation are widely used for functional design, they lack a systematic approach when used for reliability assessments. Besides this, lifetime predictions are still based on old standards assuming a constant failure rate behavior. In this chapter, we will present the reliability and failures found in solid-state lighting systems. It includes both degradation and catastrophic failure modes from observation toward a full description of its mechanism obtained by extensive use of acceleration tests using knowledge-based qualification methods