Techno-economic assessment of providing control energy reserves with a biogas plant

Grid stability is being challenged by the increasing integration of power plants with volatile power generation into the energy system. Power supply fluctuations must be compensated by energy system flexibility. The storability of the energy carrier enables biogas plants to generate power flexibly. In this study, the technical and economic effects of providing positive secondary control energy reserves with an Austrian biogas plant were assessed. The plant’s main focus lies in biomethane production with the option of heat and power generation through combined heat and power (CHP) units. A detailed simulation model of the investigated biogas plant was developed, which is presented in this work. Ex-post simulations of one year of flexible plant operation were conducted with this model. The findings show that the installed biogas storage capacity is sufficient to provide control energy reserves while simultaneously producing biomethane. Profitability of providing control energy reserves largely depends on the prices at the control energy market and on CHP unit start-up costs. A cost efficiency analysis demonstrated that investing in a hot water tank with a volume of 5 m³ for short-term heat storage turned out to be economically viable.

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Benefits, limitations and uncertainty of in situ spectrometry.

In situ spectrometers are comparable robust instruments and can be operated long term with relatively low maintenance demand. The decisive factor for their applicability is the development of a medium and installation location specific correlation model, which estimates the concentration of the requested target parameter from the measured absorption values. In some cases it might turn out, that the development of a single site specific correlation model is not sufficient, due to frequent and substantial variations of the (waste) water composition.In order to assess the total uncertainty of in situ spectrometry, a comprehensive lab test was carried out. It includes a detailed investigation of the uncertainty of CODreference methods (DIN and small tube tests), a precision analysis of the absorption spectra and the impact of those two factors on the total uncertainty of the COD(EQ) correlation model.     

Comparison of and uncertainties in raw sewage COD measurements by laboratory techniques and field UV-visible spectrometry.

A comprehensive investigation of the uncertainty of different COD analysis methods (DIN, small tube tests (STT) and UV-visible spectrometry methods) has been carried out on potassium hydrogen phthalate standard solutions and raw sewage samples from a large wastewater treatment plant. The UV-visible method allows estimating COD equivalent concentration from the measured absorption spectra by means of site specific regression and correlation functions. CODdin and CODstt methods showed equivalent global results but specific calibration relationships are necessary when high accuracy is required. The CODstt method is suitable for immediate COD analysis in the field. Sub-sampling is the main source of uncertainty. Spectrometry is able to estimate CODeq with an uncertainty of the same order of magnitude as the uncertainty in CODdin.     

Investigative monitoring in the context of detecting anthropogenic impact on an epipotamal river.

In the context of an investigative monitoring programme a monitoring system comprising of a water quality monitoring station and a camera station has been installed and operated for more than one year. The monitoring target was to investigate changes of water quality which can be related to a repeated occurrence of foam, observed at a river stretch downstream the monitoring station. The extent and frequency of foam buildup was recorded by means of the camera station.The analysis of the online data clearly showed that some of the measured parameters can be used as indicators for specific discharges, which from additional targeted investigations could be identified as contributors to the foaming problems. The continuous ammonium measurement could be used to detect nitrification problems of WWTPs discharging upstream of the monitoring station.By combining different data sources (emission data, operative and investigative monitoring data) additional information can be gained, which can be used for a comprehensive data assessment as well as a detailed system analysis.     

Changes in the normal liver fibrinolytic activity after portacaval anastomosis in experimental animals (1st communication)

One hundred twenty-one patients with disseminated malignant melanoma were treated with BCNU, vincristine, DTIC, and chlorpromazine (BVD). A response rate of 22% was observed; 28% of the patients had stable disease and 50% had increasing disease. Similar response rates were obtained with both the high dose and low dose treatment schedules. Patients who exhibited some degree of improvement during their initial course of treatment had the highest overall response rate (72%) to BVD chemotherapy. The median survival from onset of therapy was six months for all patients and 18 months for patients who responded to chemotherapy. The median duration of response was 9.9 months. Thus, the addition of chlorpromazine to BVD chemotherapy did not increase tumor response, and the overall results obtained were comparable to DTIC alone. Patients were found to be lymphopenic prior to the onset of therapy. Their median absolute lymphocyte count was 1800/mm3. Those patients with absolute lymphocyte counts above the 2710/mm3 normal mean had significantly higher response rates (35% vs. 19%, P less than .05) and longer survivals (9.8 months vs. 4.3 months, P less than .05) than patients with lower initial lymphocyte levels. Pretreatment eosinophil and monocyte counts were not closely correlated with patient response or survival.     

A Novel Approach to Data Encryption Based on Matrix Computations

In this paper, we provide a new approach to data encryption using generalized inverses. Encryption is based on the implementation of weighted Moore–Penrose inverse A^†_MN(nxm) over the nx8 constant matrix. The square Hermitian positive definite matrix N_8x8 p is the key. The proposed solution represents a very strong key since the number of different variants of positive definite matrices of order 8 is huge. We have provided NIST (National Institute of Standards and Technology) quality assurance tests for a random generated Hermitian matrix (a total of 10 different tests and additional analysis with approximate entropy and random digression). In the additional testing of the quality of the random matrix generated, we can conclude that the results of our analysis satisfy the defined strict requirements. This proposed MP encryption method can be applied effectively in the encryption and decryption of images in multi-party communications. In the experimental part of this paper, we give a comparison of encryption methods between machine learning methods. Machine learning algorithms could be compared by achieved results of classification concentrating on classes. In a comparative analysis, we give results of classifying of advanced encryption standard (AES) algorithm and proposed encryption method based on Moore–Penrose inverse.     

Enhanced WSN Routing Protocol for Internet of Things to Process Multimedia Big Data

Wireless Personal Communications - At a time when the Delay Tolerant Network (DTN) Research Group is making great strides in establishing the much anticipated Solar System Internet (SSI) in space,...     

Application of ion-sensitive sensors in water quality monitoring.

Within the last years a trend towards in-situ monitoring can be observed, i.e. most new sensors for water quality monitoring are designed for direct installation in the medium, compact in size and use measurement principles which minimise maintenance demand. Ion-sensitive sensors (Ion-Sensitive-Electrode--ISE) are based on a well known measurement principle and recently some manufacturers have released probe types which are specially adapted for application in water quality monitoring. The function principle of ISE-sensors, their advantages, limitations and the different methods for sensor calibration are described. Experiences with ISE-sensors from applications in sewer networks, at different sampling points within wastewater treatment plants and for surface water monitoring are reported. An estimation of investment and operation costs in comparison to other sensor types is given.     

The mesoporosity of microparticles spray dried from trehalose and nanoparticle hydroxyapatite depends on the ratio of nanoparticles to sugar and nanoparticle surface charge

The ratio of hydroxyapatite (HA) nanoparticles (NP) to trehalose in composite microparticle (MP) vaccine vehicles by determining inter-nanoparticle space potentially influences antigen release. Mercury porosimetry and gas adsorption analysis have been used quantify this space. Larger pores are present in MPs spray dried solely from nanoparticle gel compared with MPs spray dried from nanoparticle colloid which have less inter-nanoparticle volume. This is attributed to tighter nanoparticle packing caused by citrate modification of their surface charge. The pore size distributions (PSD) for MP where the trehalose has been eliminated by combustion generally broaden and shifts to higher values with increasing initial trehalose content. Modal pore size, for gel derived MPs is comparable to modal NP width below 30% initial trehalose content and approximates to modal NP length (~50 nm) at 60% initial trehalose content. For colloidally derived MPs this never exceeds the modal NP width. Pore-sizes are comparable, to surface inter-nanoparticle spacings observed by SEM.