Self-heating of anaerobic digesters using energy crops

2006 ◽  
Vol 53 (8) ◽  
pp. 159-166 ◽  
Author(s):  
H. Lindorfer ◽  
R. Braun ◽  
R. Kirchmayr
Keyword(s):  
Energy Crops ◽  
Full Scale ◽  
Heat Fluxes ◽  
The Self ◽  
External Energy ◽  
Anaerobic Digesters ◽  
Self Heating ◽  
Biogas Plants ◽  
High Starch ◽  
The Impact

With the increasing application of energy crops in agricultural biogas plants and increasing digester volumes, the phenomenon of self-heating in anaerobic digesters appeared in some cases. Until now this development was just known from aerobic systems. To obtain an idea of the thermodynamics inside an anaerobic digester, a detailed analysis of all heat fluxes in a full-scale agricultural biogas plant was carried out. Several experiments were realised to quantify the influences of different internal and external energy sources. To estimate the impact of self-heating in anaerobic systems, data of other full-scale agricultural biogas plants in Austria were collected. Alternatives to the cooling of the digesters are discussed based on individual experiences of several plants. A connection between carbohydrate-rich substrates, especially with high starch contents, and the self-heating could be shown. From the results it can be assumed that the anaerobic digestion of most energy crops is exothermic, which is in contrast to the current thermodynamic belief.

scholarly journals The impact of immigration on microbial community composition in full-scale anaerobic digesters

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Rasmus H. Kirkegaard ◽  
Simon J. McIlroy ◽  
Jannie M. Kristensen ◽  
Marta Nierychlo ◽  
Søren M. Karst ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Microbial Community Composition ◽  
Full Scale ◽  
Anaerobic Digesters ◽  
The Impact

Operational results of an agricultural biogas plant equipped with modern instrumentation and automation

2008 ◽  
Vol 57 (6) ◽  
pp. 803-808 ◽  
Author(s):  
J. Wiese ◽  
O. Kujawski
Keyword(s):  
Energy Crops ◽  
Full Scale ◽  
Biogas Plant ◽  
Biogas Plants ◽  
Technical Details ◽  
Modern Instrumentation

Agricultural biogas plants based on energy crops gain more and more importance because of numerous energetic, environmental and agricultural benefits. In contrast to older biogas plants, the newest generation of biogas plants is equipped with modern ICA equipment and reliable machines/engines. In this paper, the authors present technical details and operational results of a modern full-scale agricultural biogas plant using energy crops.

scholarly journals The Use of Biodrying to Prevent Self-Heating of Alternative Fuel

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3039 ◽  
Author(s):  
Teresa Gajewska ◽  
Mateusz Malinowski ◽  
Maciej Szkoda
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Calorific Value ◽  
Alternative Fuel ◽  
The Self ◽  
Process Efficiency ◽  
Self Heating ◽  
Maximum Temperatures ◽  
Refuse Derived Fuels ◽  
The Impact

Alternative fuels (refuse-derived fuels—RDF) have been a substitute for fossil fuels in cement production for many years. RDF are produced from various materials characterized by high calorific value. Due to the possibility of self-ignition in the pile of stored alternative fuel, treatments are carried out to help protect entrepreneurs against material losses and employees against loss of health or life. The objective of the research was to assess the impact of alternative fuel biodrying on the ability to self-heat this material. Three variants of materials (alternative fuel produced on the basis of mixed municipal solid waste (MSW) and on the basis of bulky waste (mainly varnished wood and textiles) and residues from selective collection waste (mainly plastics and tires) were adopted for the analysis. The novelty of the proposed solution consists in processing the analyzed materials inside the innovative ecological waste apparatus bioreactor (EWA), which results in increased process efficiency and shortening its duration. The passive thermography technique was used to assess the impact of alternative fuel biodrying on the decrease in the self-heating ability of RDF. As a result of the conducted analyses, it was clear that the biodrying process inhibited the self-heating of alternative fuel. The temperature of the stored fuel reached over 60 °C before the biodrying process. However, after the biodrying process, the maximum temperatures in each of the variants were about 30 °C, which indicates a decrease in the activity of microorganisms and the lack of self-ignition risk. The maximum temperatures obtained (>71 °C), the time to reach them (≈4 h), and the duration of the thermophilic phase (≈65 h) are much shorter than in the studies of other authors, where the duration of the thermophilic phase was over 80 h.

scholarly journals Determination of mixing quality in biogas plant digesters using tracer tests and computational fluid dynamics

2013 ◽  
Vol 61 (5) ◽  
pp. 1269-1278 ◽  
Author(s):  
Luděk Kamarád ◽  
Stefan Pohn ◽  
Günther Bochmann ◽  
Michael Harasek
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Demand ◽  
Biogas Production ◽  
Tracer Tests ◽  
Full Scale ◽  
Biogas Plant ◽  
Tracer Concentration ◽  
Anaerobic Digesters ◽  
Biogas Plants

The total electricity demand of investigated biogas plants (BGP) makes up 7–8 % of the total electricity produced. Nearly 40 % of this energy is consumed just for mixing in digesters and the energy demand for mixing in some biogas plants can be even higher. Therefore, optimal mixing in anaerobic digesters is a basic condition for efficient plant operation and biogas production. The use of problematic substrates (e.g. grass silage or other fibrous substrates), installation of unsuitable mixing systems or inconvenient mixing intervals may lead to mixing problems. Knowledge about mixing in biogas digesters is still insufficient, so the objective of this study was to fill the information gaps in the literature by determining the minimal retention time of substrates fed into anaerobic digesters and to describe substrate distribution and washing out rates from investigated digesters. Two full-scale biogas plant digesters (2000 m3 and 1500 m3) using different mixing systems and substrates were investigated. To characterize the substrate distribution, lithium hydroxide monohydrate solutions were used for tracer tests at concentrations of 47.1 mg Li+ / kg TS and 46.6 mg Li+ / kg TS in digester. The tracer concentration in the digester effluents was measured during two hydraulic retention times and compared. Although the tracer was detected in the digester effluent at nearly the same time in both cases, the tracer tests showed very different distribution curves. The tracer concentration in effluent B grew much slower than in effluent A and no significant short circuiting streams were detected. Although the data calculated by computational fluid dynamics methods (CFD) showed a very good agreement with the full scale results, full comparison was not possible.

scholarly journals Self-heating effect on logic performance of 6T-SRAM based on CFET device

2021 ◽  
Author(s):  
Songhan Zhao ◽  
Yandong He ◽  
Xiaoyan Liu ◽  
Gang Du
Keyword(s):  
Vertical Structure ◽  
The Self ◽  
Heating Effect ◽  
Circuit Performance ◽  
Self Heating ◽  
Gate Capacitance ◽  
Noise Margin ◽  
And Performance ◽  
The Impact ◽  
Static Noise

Abstract CFET devices have become emerging and promising candidates for continuing Moore's law at sub-3 nm nodes owing to the area advantage of the N-P stacked structure, which markedly improves the integration of circuits. However, the introduction of vertical structure leads to severe thermal issues due to the self-heating effect, resulting in the degradation of the device and circuit performance. This paper mainly evaluates and analyzes the performance of the SRAM unit built using the CFET structure. The CFET-SRAM exhibits better performance than the conventional CMOS-SRAM in terms of access delay, even with the impact of self-heating. For the multi-fin-based CFET, although the total gate capacitance increases, the enhanced current improves the static noise margin significantly. However, as the number of channels expands, sheet-based CFET devices show more comprehensive superiority of area and performance.

scholarly journals Occurrence of Thermophilic Microorganisms in Different Full Scale Biogas Plants

2019 ◽  
Vol 21 (1) ◽  
pp. 283 ◽  
Author(s):  
Ivan Kushkevych ◽  
Jiří Cejnar ◽  
Monika Vítězová ◽  
Tomáš Vítěz ◽  
Dani Dordević ◽  
...  
Keyword(s):  
Large Scale ◽  
16S Rrna Gene Sequencing ◽  
Biogas Plant ◽  
Pig Manure ◽  
Rrna Gene ◽  
Anaerobic Digesters ◽  
Thermophilic Microorganisms ◽  
Plant Operator ◽  
Biogas Plants ◽  
The Impact

Background: In recent years, various substrates have been tested to increase the sustainable production of biomethane. The effect of these substrates on methanogenesis has been investigated mainly in small volume fermenters and were, for the most part, focused on studying the diversity of mesophilic microorganisms. However, studies of thermophilic communities in large scale operating mesophilic biogas plants do not yet exist. Methods: Microbiological, biochemical, biophysical methods, and statistical analysis were used to track thermophilic communities in mesophilic anaerobic digesters. Results: The diversity of the main thermophile genera in eight biogas plants located in the Czech Republic using different input substrates was investigated. In total, 19 thermophilic genera were detected after 16S rRNA gene sequencing. The highest percentage (40.8%) of thermophiles was found in the Modřice biogas plant where the input substrate was primary sludge and biological sludge (50/50, w/w %). The smallest percentage (1.87%) of thermophiles was found in the Čejč biogas plant with the input substrate being maize silage and liquid pig manure (80/20, w/w %). Conclusions: The composition of the anaerobic consortia in anaerobic digesters is an important factor for the biogas plant operator. The present study can help characterizing the impact of input feeds on the composition of microbial communities in these plants.

scholarly journals Szarvasi-1 and its Potential to Become a Substitute for Maize Which is Grown for the Purposes of Biogas Plants in the Czech Republic

Agronomy ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 98 ◽  
Author(s):  
Jaroslav Bernas ◽  
Jan Moudrý ◽  
Marek Kopecký ◽  
Petr Konvalina ◽  
Zdeněk Štěrba
Keyword(s):  
Renewable Energy ◽  
Czech Republic ◽  
Phalaris Arundinacea ◽  
Energy Crops ◽  
Energy Unit ◽  
The Czech Republic ◽  
Environmental Burden ◽  
Yield Rate ◽  
Biogas Plants ◽  
The Impact

The domestic biogas market has been developing rapidly, and legislation (The Act) supporting the use of renewable energy sources has come into force. In light of this act and investment support from national programs co-financed by the European Union (EU), the total number of biogas plants has recently increased from a few to 670. The total capacity of electricity generation of those 670 installed plants exceeds 360 Megawatts (MW) (as of mid-2018). Such dynamic growth is expected to continue, and the targets of the National Renewable Energy Action Plan are projected to be met. The use of waste material, which was urgently needed, was the original aim of biogas plants. However, in certain cases, the original purpose has transformed, and phytomass is very often derived from purpose-grown energy crops. Maize is the most common and widely grown energy crop in the Czech Republic. Nevertheless, maize production raises several environmental issues. One way to potentially reduce maize’s harmful effects is to replace it with other suitable crops. Perennial energy crops, for example, are possible alternatives to maize. A newly introduced species for the conditions of the Czech Republic, Elymus elongatus subsp. ponticus cv. Szarvasi-1, and some other well-known species—Phalaris arundinacea L. and Miscanthus × giganteus—are suitable for Czech Republic climate conditions. This paper presents the findings of the research and evaluation of environmental, energy-related, and economic aspects of growing these crops for use in biogas plants. These findings are based on 5-year small-plot field trials. The energy-related aspects of producing Elymus elongatus subsp. ponticus cv. Szarvasi-1, Phalaris arundinacea L., and Miscanthus x giganteus are reported on the basis of experiments that included measuring the real methane yield from a production unit. The economic analysis is based on a model of every single growing and technological operation and costs. The environmental burden of the individual growing methods was assessed with a simplified life cycle assessment (LCA) using the impact category of Climate Change and the SimaPro 8.5.2.0 software tool, including an integrated method called ReCiPe. The research findings show that Szarvasi-1 produces 5.7–6.7 Euros (EUR) per Gigajoule (GJ) of energy, depending on the growing technology used. Szarvasi-1 generates an average energy profit of 101.4 GJ ha−1, which is half of that produced by maize (214.1 GJ ha−1). The environmental burden per energy unit of maize amounts to 16 kg of carbon dioxide eq GJ−1 compared with the environmental burden per energy unit of Szarvasi-1, which amounts to 7.2–15.6 kg of CO2 eq GJ−1, depending on the yield rate. On the basis of the above-mentioned yield rate of Szarvasi-1, it cannot be definitively recommended for the purpose of biogas plants in the Czech Republic.

The impact of the thermal conductivity of a dielectric layer on the self-heating effect of a graphene transistor

Nanoscale ◽  
2015 ◽  
Vol 7 (32) ◽  
pp. 13561-13567 ◽  
Author(s):  
T. S. Pan ◽  
M. Gao ◽  
Z. L. Huang ◽  
Y. Zhang ◽  
Xue Feng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Layer ◽  
The Self ◽  
Heating Effect ◽  
Self Heating ◽  
The Impact

scholarly journals Monitoring of seven industrial anaerobic digesters supplied with biochar

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Kerstin Heitkamp ◽  
Adriel Latorre-Pérez ◽  
Sven Nefigmann ◽  
Helena Gimeno-Valero ◽  
Cristina Vilanova ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Methanogenic Archaea ◽  
Amplicon Sequencing ◽  
Joint Analysis ◽  
Rrna Gene ◽  
Anaerobic Digesters ◽  
Metabolic Route ◽  
Biogas Plants ◽  
One Year ◽  
The Impact

Abstract Background Recent research articles indicate that direct interspecies electron transfer (DIET) is an alternative metabolic route for methanogenic archaea that improves microbial methane productivity. It has been shown that multiple conductive materials such as biochar can be supplemented to anaerobic digesters to increase the rate of DIET. However, the industrial applicability, as well as the impact of such supplements on taxonomic profiles, has not been sufficiently assessed to date. Results Seven industrial biogas plants were upgraded with a shock charge of 1.8 kg biochar per ton of reactor content and then 1.8 kg per ton were added to the substrate for one year. A joint analysis for all seven systems showed a decreasing trend for the concentration of acetic acid (p < 0.0001), propionic acid (p < 0.0001) and butyric acid (p = 0.0022), which was significant in all cases. Quantification of the cofactor F420 using fluorescence microscopy showed a reduction in methanogenic archaea by up to a power of ten. Methanogenic archaea could grow within the biochar, even if the number of cells was 4 times less than in the surrounding sludge. 16S-rRNA gene amplicon sequencing showed a higher microbial diversity in the biochar particles than in the sludge, as well as an accumulation of secondary fermenters and halotolerant bacteria. Taxonomic profiles indicate microbial electroactivity, and show the frequent occurrence of Methanoculleus, which has not been described in this context before. Conclusions Our results shed light on the interplay between biochar particles and microbial communities in anaerobic digesters. Both the microbial diversity and the absolute frequency of the microorganisms involved were significantly changed between sludge samples and biochar particles. This is particularly important against the background of microbial process monitoring. In addition, it could be shown that biochar is suitable for reducing the content of inhibitory, volatile acids on an industrial scale.

Sign in / Sign up

Export Citation Format

Share Document