The ignis fatuus of biogas. Small-scale anaerobic digesters (biogas plants): A critical review of the pre-1970 literature

1982 ◽  
Vol 4 (1) ◽  
pp. 80-81
Author(s):  
P.H.
Keyword(s):  
Critical Review ◽  
Small Scale ◽  
Anaerobic Digesters ◽  
Biogas Plants

scholarly journals Small-scale anaerobic digesters in Vietnam – development and challenges

2011 ◽  
Vol 1 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Vo Chau Ngan Nguyen
Keyword(s):  
Waste Treatment ◽  
Small Scale ◽  
Viet Nam ◽  
Livestock Waste ◽  
Current Development ◽  
Comprehensive Overview ◽  
Anaerobic Digesters ◽  
Biogas Plants ◽  
Small Scale Farmers ◽  
Biogas Technology

Small-scale anaerobic digesters, known as biogas plants, were applied as an optimal livestock waste treatment as well as biogas supply for cooking and lighting demand for small-scale farmers in Vietnam. Although the biogas technology was introduced for nearly 30 years, the number of the constructed biogas plants is still limited. The current development of biogas plants is far below the real demand on livestock waste treatment that has increased significantly. This paper gives a comprehensive overview on the biogas plant development in Vietnam and attempts to address the challenges and discuss appropriate solutions for the further biogas development. Mô hìnhlên men yếm khíquy mô nhỏ (được biếtvới tên hầm ủ khí sinh học) đã được ứng dụng hiệu quả trongxử lý chất thải chăn nuôicũng nhưcung cấpnguồn nhiên liệu phục vụ nhu cầu nấu ănvàthắp sáng cho các hộ chăn nuôi nhỏ ở Việt Nam. Mặc dù đã hiện diện gần 30 năm, nhưng số lượng hầm ủ khí sinhhọc vẫn còn hạn chế. Sự gia tăng số lượnghầm ủ khí sinh học chưa theo kịp với nhu cầu về xử lý chất thải chăn nuôi đang ngày càng gia tăng. Bài báo trình bày các chặng đường phát triển của hầm ủ khí sinh học tại Việt Nam, ghi nhận các thách thức trong việcnhân rộng hầm ủ khí sinh họctrong thực tế và thảo luận một sốgiải pháp để phát triển công nghệ khí sinh học.

scholarly journals Improvement of Biogas Quality and Quantity for Small-Scale Biogas-Electricity Generation Application in off-Grid Settings: A Field-Based Study

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3088
Author(s):  
Henry Wasajja ◽  
Saqr A. A. Al-Muraisy ◽  
Antonella L. Piaggio ◽  
Pamela Ceron-Chafla ◽  
Purushothaman Vellayani Aravind ◽  
...  
Keyword(s):  
Electricity Generation ◽  
Relevant Literature ◽  
Electrical Power ◽  
Process Efficiency ◽  
Electricity Production ◽  
Small Scale ◽  
Buffer System ◽  
Biogas Plants ◽  
Operational Practices ◽  
Pre Treatment

Small-scale electrical power generation (<100 kW) from biogas plants to provide off-grid electricity is of growing interest. Currently, gas engines are used to meet this demand. Alternatively, more efficient small-scale solid oxide fuel cells (SOFCs) can be used to enhance electricity generation from small-scale biogas plants. Most electricity generators require a constant gas supply and high gas quality in terms of absence of impurities like H2S. Therefore, to efficiently use the biogas from existing decentralized anaerobic digesters for electricity production, higher quality and stable biogas flow must be guaranteed. The installation of a biogas upgrading and buffer system could be considered; however, the cost implication could be high at a small scale as compared to locally available alternatives such as co-digestion and improved digester operation. Therefore, this study initially describes relevant literature related to feedstock pre-treatment, co-digestion and user operational practices of small-scale digesters, which theoretically could lead to major improvements of anaerobic digestion process efficiency. The theoretical preamble is then coupled to the results of a field study, which demonstrated that many locally available resources and user practices constitute frugal innovations with potential to improve biogas quality and digester performance in off-grid settings.

Rural Energy in Kenya: Is There a Future for Biogas? A Survey

1989 ◽  
Vol 7 (2) ◽  
pp. 116-127 ◽  
Author(s):  
Justas K. Laichena
Keyword(s):  
Crop Residues ◽  
Muscle Power ◽  
Gas Production ◽  
Energy Crisis ◽  
Small Scale ◽  
Ic Engine ◽  
Rural Energy ◽  
Animal Dung ◽  
Biogas Plants ◽  
Biogas Technology

Most rural people in Kenya rely principally on human and animal muscle power in their work as subsistence farmers, herdsmen, fisherman, or small-scale crop farmers. All the agricultural processes (ranging from ploughing to harvesting) are done largely by hand, with some help from draft animals and simple tools. Firewood is their principal cooking and heating fuel while kerosene in used for lighting. Their economic growth is hence blocked by the energy crisis. Due to their heavy dependence on biomass – mainly firewood, crop residues, and animal dung – they deprive the soil of essential nutrients and pose a threat to the agricultural lands due to deforestation and the resulting soil erosion. The problem of rural energy, therefore places the provision of food and other basic needs at risk. A technology which extracts a more useful and convenient form of fuel from biomass without destroying its fertilizer value than the traditional conversion method of direct combustion is highly desirable. Anaerobic digestion of agricultural residues generates biogas which can be used directly for lighting, cooking, electricity generation, or to power an IC engine for water pumping or milling. The remaining sludge forms a good fertilizer. This paper reviews the role of biomass in meeting Kenya's energy needs and how biogas can contribute in alleviating the rural energy crisis. Biogas production and utilization technology was introduced in Kenya in 1954 but by 1986 there were less than 200 installed biogas plants and less than 25% of these were operational. A survey of installed biogas plants (across the country) was carried out (using questionnaires and interviews) to identify the factors that have inhibited the adoption of biogas technology in Kenya; and the problems which have caused the failure of many of the installed plants. The paper gives a detailed discussion of the findings. The survey showed that amoung the reasons for nonadoption are: lack of capital and sufficient input materials (animal dung and water); limited dissemination of technical knowledge and experience to operate biogas plants; and the lack of credit and extension facilities. It was also found that problems such as scum build-up and corrosion, and the lack of sufficient knowledge on the operation and maintenance of the digesters especially on feeding and feedstock dilution (leading to low gas production) has resulted to many failures. The paper attempts to answer some of the problems which have resulted to the many failures and hindered widespread acceptance of biogas technology in Kenya. Finally the issue of dissemination is discussed.

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 Use of a Formative Pedagogy Lens to Enhance and Maintain Virtual Supervisory Relationships: Appreciative Inquiry and Critical Review (Preprint)

2020 ◽  
Author(s):  
Chloe Louanne Jordan ◽  
Thillainathan Sathaananthan ◽  
Leo Anthony Celi ◽  
Linda Jones ◽  
M Abdulhadi Alagha
Keyword(s):  
Appreciative Inquiry ◽  
Critical Review ◽  
Sense Of Self ◽  
Virtual Learning ◽  
Careful Consideration ◽  
Small Scale ◽  
Successful Implementation ◽  
Web Based ◽  
Supervisory Relationships ◽  
Student Relationship

BACKGROUND Virtual supervisory relationships provide an infrastructure for flexible learning, global accessibility, and outreach, connecting individuals worldwide. The surge in web-based educational activities in recent years provides an opportunity to understand the attributes of an effective supervisor-student or mentor-student relationship. OBJECTIVE The aim of this study is to compare the published literature (through a critical review) with our collective experiences (using small-scale appreciative inquiry [AI]) in an effort to structure and identify the dilemmas and opportunities for virtual supervisory and mentoring relationships, both in terms of stakeholder attributes and skills as well as providing instructional recommendations to enhance virtual learning. METHODS A critical review of the literature was conducted followed by an AI of reflections by the authors. The AI questions were derived from the 4D AI framework. RESULTS Despite the multitude of differences between face-to-face and web-based supervision and mentoring, four key dilemmas seem to influence the experiences of stakeholders involved in virtual learning: informal discourses and approachability of mentors; effective virtual communication strategies; authenticity, trust, and work ethics; and sense of self and cultural considerations. CONCLUSIONS Virtual mentorship or supervision can be as equally rewarding as an in-person relationship. However, its successful implementation requires active acknowledgment of learners’ needs and careful consideration to develop effective and mutually beneficial student-educator relationships.

scholarly journals Absorption Chillers to Improve the Performance of Small-Scale Biomethane Liquefaction Plants

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 92
Author(s):  
Alessio Ciambellotti ◽  
Gianluca Pasini ◽  
Andrea Baccioli ◽  
Lorenzo Ferrari ◽  
Stefano Barsali
Keyword(s):  
Natural Gas ◽  
Waste Heat ◽  
Economic Assessment ◽  
Specific Consumption ◽  
Small Scale ◽  
Agricultural Activities ◽  
Electricity Cost ◽  
Absorption Chillers ◽  
Levelized Cost ◽  
Biogas Plants

Biomethane liquefaction may help decarbonization in heavy transportation and other hard-to-abate sectors. Small-scale liquefaction plants (<10 ton/day) are suitable for small biogas plants located near farms and other agricultural activities. “Internal refrigerant” refrigeration cycles (e.g., Kapitza cycle) are often proposed for small-scale natural gas liquefaction due to their simplicity. An optimized Kapitza-based cycle is modeled and simulated, and then several modifications were studied to evaluate their influence on the energetic and economic performances. Results showed a specific consumption ranging between 0.65 kWh/kg and 0.54 kWh/kg of bio-LNG with no significant improvements by increasing cycle complexity. Instead, a reduction of 17% was achieved with the implementation of absorption chillers, that effectively turn waste heat into useful cooling energy. An economic assessment was finally carried showing that the Levelized Cost of Liquefation is more affected by electricity cost than additional CapEx.

scholarly journals Effects of the German Renewable Energy Sources Act and environmental, social and economic factors on biogas plant adoption and agricultural land use change

2020 ◽  
Author(s):  
Xueqing Yang ◽  
Yang Liu ◽  
Daniela Thrän ◽  
Alberto Bezama ◽  
Mei Wang
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Biogas Production ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Small Scale ◽  
Agricultural Land Use ◽  
Economic Factors ◽  
Silage Maize ◽  
Biogas Plants

Abstract Background: The German energy transition strategy calls for a reform of the German energy sector. As a result, the Germany Renewable Energy Sources Act (EEG) was passed in 2000 and is widely regarded as successful legislation for promoting bioenergy development. More than 1,000 biogas plants were constructed in Central Germany (CG) between 2000 and 2014. Despite this, few studies have been conducted for this period that systematically investigate how environmental, social and economic factors, as well as various EEG amendments have impacted biogas production and what the environmental consequence of biogas production development in CG have been. Methods: The impacts of environmental, social and economic factors and different EEG amendments on biogas production decisions in CG were quantified using multivariate linear regression model and the event study econometric technique. A GIS-based spatial analysis was also conducted to provide insight into the changes to agricultural land use that resulted from the development of biogas plants during the EEG period. Results: The main finding was that the income diversification effect resulting from biogas production was the most important factor in a farmer’s decision to adopt biogas production. In addition, all of the EEG amendments had a significant influence on the adoption of biogas production, however EEG III and IV, which tried to promote small-scale plants, were unable to reduce the average size of the plants constructed in these two amendment periods. From a landscape perspective, there was a striking increase in the cultivation of silage maize in CG from 2000 to 2014. Silage maize was intensively cultivated in regions with a high installed biogas plant capacity. Since the first EEG amendment, permanent grassland area slightly increased while arable land area declined in CG. Conclusions: The adoption of biogas production in CG was strongly driven by economic incentives for the farmers, more precisely, by the incentive to diversify their income sources. In addition to increase the subsidy, future EEG amendments should find new measures to encourage the adoption of small-scale biogas plants, which had been unsuccessful in EEG amendments III and IV.

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