Small Biogas Research Articles

Multi-Criteria Analysis of Lignocellulose Substrate Pre-Treatment

Abstract Due to growing topicality of indirect land use change, greater shift towards second generation biofuels should be observed. In order to help smaller biogas and bioethanol producers, multi-criteria analysis of lignocellulose pre-treatment is conducted to elucidate the most preferable approach for lignocellulose pre-treatment. There are four main pre-treatment groups – biological, chemical, physical and physochemical pre-treatment. In this article three pre-treatment types were described by highlighting their specific approaches; using multi-criteria analysis a conclusion was reached that the most preferable pre-treatment option for lignocellulose biomass like corn stover or sugarcane is microbiological pre-treatment, as it showed the closest proximity to ideal solution.

Unsteady ultra-lean combustion of methane and biogas in a porous burner – An experimental study

The response of ultra-lean flames, stabilised in a porous burner, to the fluctuations imposed on the fuel flow rate is investigated experimentally. The study is motivated by the likelihood of small biogas generators to produce fuels with temporal variations in their flow rate and chemical composition. The employed porous burner includes layers of silicon carbide porous foam placed inside a quartz tube. The burner is equipped with a series of axially arranged thermocouples and is imaged by a digital camera. Methane and a blend of methane and carbon dioxide (mimicking biogas) are mixed with air and then fed to the burner at equivalence ratios below 0.3. The fuel flow rate is modulated with a programmable mass flow controller by imposing a sinusoidal wave with variable amplitude and frequency on the steady fuel flow. Through analysis of the flame images and collected temperature traces, it is shown that the imposed disturbances result in motion of the flame inside the burner. Such motion is found to qualitatively follow the temporal variation in the fuel flow for both methane and biogas. Nonetheless, the amplitude of the flame oscillations for methane is found to be higher than that for biogas. Further, it is observed that exposure of the burner to the fuel fluctuations for a long time (180 s) eventually results in flame destabilisation. However, stabilised combustion was achieved for methane mixtures at amplitudes between 0 and 30% of steady values over a period of 60 s. This study reveals the strong effects of unsteady heat transfer in porous media upon the fluctuations in flame position.

Microbiome Diversity and Community-Level Change Points within Manure-based small Biogas Plants.

Efforts to integrate biogas plants into bioeconomy concepts will lead to an expansion of manure-based (small) biogas plants, while their operation is challenging due to critical characteristics of some types of livestock manure. For a better process understanding, in this study, three manure-based small biogas plants were investigated with emphasis on microbiome diversity. Due to varying digester types, feedstocks, and process conditions, 16S rRNA gene amplicon sequencing showed differences in the taxonomic composition. Dynamic variations of each investigated biogas plant microbiome over time were analyzed by terminal restriction fragment length polymorphism (TRFLP), whereby nonmetric multidimensional scaling (NMDS) revealed two well-running systems, one of them with a high share of chicken manure, and one unstable system. By using Threshold Indicator Taxa Analysis (TITAN), community-level change points at ammonium and ammonia concentrations of 2.25 g L−1 and 193 mg L−1 or volatile fatty acid concentrations of 0.75 g L−1were reliably identified which are lower than the commonly reported thresholds for critical process stages based on chemical parameters. Although a change in the microbiome structure does not necessarily indicate an upcoming critical process stage, the recorded community-level change points might be a first indication to carefully observe the process.

The importance of governmental incentives for small biomethane plants in South Spain

Abstract A novel analysis addresses the economic viability of biomethane production from small biogas plants in South Spain, as a claim to promote the use of green energy and reduce the consumption of natural gas. To this end, the importance of governmental incentives to reach profitability in biomethane plants is illustrated through a case study. To date, no study addressing this problem specifically for South Spain can be found. The study considers the whole process from biogas production to biomethane feeding into the grid, for three different biomethane capacities (50, 100 and 150 m3/h) and includes an exhaustive sensitivity analysis. For the three cases, implementing a biomethane plant is not viable and, therefore, not attractive for investors. Results considering biomethane governmental incentives as feed-in premia show significant improvements on the profitability of the largest plants. For example, supporting 150 m3/h biomethane production capacity plants with a premium price of only 6 €/MWh (6.6 cents/m3) results in 270 k€ NPV. Nevertheless, the smallest biomethane plants are hardly feasible. Concerning governmental support through investment subsidies, 150 m3/h plants are profitable if 10% of the investment is subsidized, whereas the smallest plants do not reach profitability even if 50% of the investment is subsidized.

Micro-cogeneration based on solid oxide fuel cells: Market opportunities in the agriculture/livestock sector

Bio-waste embeds an extraordinary renewable potential, and it becomes a source of energy savings when transformed into a valuable resource, like biogas. Cogeneration (CHP) from biogas employing high-temperature Solid Oxide Fuel Cells (SOFCs) scores a high sustainability level, thanks to improved environmental and energy performances. The synergy between the niche market of small/micro biogas producers and SOFCs might act as a springboard to open market opportunities for both SOFC commercialization and business upgrade of small farms. However, local regulations, waste management, renewable energy subsidies and, above all, availability of eligible sites, determine real chances for on-the-ground implementation.Through a detailed analysis of the application scenario, this research aims at investigating opportunities for the experimentation of SOFC–CHP in small biogas plants and identifying the possible bottlenecks for future deployment. When it becomes relevant, energy conversion of livestock (especially cattle and swine) and agriculture waste requires SOFC modules from 10 kWe to 35 kWe. This is in line with the current status of SOFC suppliers. Moreover, considering the fuel cell market roll-out, the average levelized cost of electricity is expected to decrease from 0.387 €/kWh to 0.115 €/kWh, when electricity is produced from livestock waste available on-site.

Suitability of small-scale biogas systems based on livestock manure for the rural areas of Sumatra

The increasing demand for farm animal products leads to higher pressure on the effective treatment of animal waste. Based on practice from other countries, biogas systems offer several significant advantages in terms of energy, environmental and economic development. Therefore, this paper investigates the potential development of small-scale biogas systems and their suitability in rural parts of northern Sumatra. A baseline field survey using semi-structured personal interviews based on questionnaires was carried out among randomly selected rural households (n = 196) in northern Sumatra in July-August 2014. The follow-up field visits to verify the results from the first stage were organised in August–September 2016. The findings show that only small individual farmers, who own 2–5 cattle heads spread on pastures, face difficulties to collect the dung. Other farmers report enough cattle manure to cover feedstock for biogas production. The calculations show sufficient animal waste feedstock supply and consequently estimated potential of energy from biogas (845 TJy−1) in the region. Nevertheless, the respondents manage animal manure only with composting (65% of respondents) and with sun-drying for fuel purposes (6%); often they leave manure fallow. The surveyed households use mostly a combination of subsidized LPG and electricity as a primary energy source for food and feed preparation, supplemented by fuelwood as the secondary source. Only half of the respondents have some knowledge about biogas technology and its benefits. The potential for small biogas systems development in the region is supported with a sufficient amount of animal manure as feedstock and suitable designs of biogas digesters on one hand; and on the other hand, impeded by challenges related to low information accessibility and investment power of rural households.

Removal of hydrogen sulfide using a photocatalytic livestock biogas desulfurizer

The objective of this study was to develop a simple operating photocatalytic biogas desulfurizing reactor (PDR) using sol-gel preparation assay in coordination with biogas absorption chiller. Hydrogen sulfide in biogas can be oxidized to SO2 by photocatalytic oxidation of TiO2-coated carriers with UV irradiation. This PDR method is the lowest maintenance cost and simple operation for small biogas consumption users water than packed scrubber or granular ferric oxide filter. Experimental results showed that H2S removal efficiency by the first PDR was 99.1 ± 1.1, 92.9 ± 2.9, 88.2 ± 3.6, 84.1 ± 2.3, and 82.7 ± 9.4% under biogas flow rate at 1, 2, 3, 4, and 5 L/min, respectively. Removal efficiency of H2S at biogas flow rate at 1 L/min was significantly different from the other biogas flow rate sets (P < 0.05). Experimental results showed that total H2S removal efficiency for all biogas flow sets was more than 99% by the dry PDR. Thus, this implies that the photocatalytic reactor can be applied to remove H2S from biogas. The successful development of the PDR can help to promote utilization efficiency of livestock biogas and reduce livestock’s greenhouse gas emissions.

Preface

It is our great pleasure to welcome you to 2019 International Conference on Environment Sciences and Renewable Energy (ESRE 2019) which will be held in Bali, Indonesia during May 27-29, 2019. ESRE 2019 is dedicated to issues related to Environment Sciences and Renewable Energy.The major goal and feature of the conference is to bring academic scientists, engineers, industry researchers together to exchange and share their experiences and research results, and discuss the practical challenges encountered and the solutions adopted. Prof. Tjokorda Gde Tirta Nindhia from Udayana University, Indonesia delivered keynote speech with the title” Design and manufacturing small biogas fueled engine for electric generation”. And Prof. Hami Alpas from Middle East Technical University, Metu_ Food Eng. Dept, Ankara, Turkey had keynote speech with the title” High Hydrostatic Pressure (Hhp) Engaged With Time Domain Nuclear Magnetic Resonance (Nmr)”. Assoc. Prof. Gun-Hean Chong from Universiti Putra Malaysia, Malaysia delivered keynote speech” A low temperature approach for producing and tailor-made powders: supercritical carbon dioxide”. Besides, Many researchers, engineers, academics as well as industrials from all over the world have presented their research results during the session presentations.This proceeding present a selection from papers submitted to the conference from universities, research institutes and industries. All papers were subjected to peer-review by conference committee members and international reviewers. The papers selected depended on their quality and their relevancy to the conference. The volume tends to present to the readers the recent advances in the field of Environment Sciences and Renewable Energy and various related areas, such as Environmental Chemistry and Biology, Waste Disposal and Recycling, Machines and wind farms, PV manufacture, testing and certification, Environmental Protection, etc.We would like to thank all the authors who have contributed to this volume, and also the organizing committee, reviewers, speakers, chairpersons, sponsors and all the conference participants for their support to ESRE 2019.Prof. Tjokorda Gde Tirta NindhiaUdayana University, IndonesiaJune 12, 2019

Investigation on the influence of membrane selectivity on the performance of mobile biogas upgrading plants by process simulation

Upgrading technologies for producing a high quality biomethane from biogas are of growing interest due to phasing out of European feed-in tariffs for biogas-based electricity. Operators of small biogas plants need alternatives to common stationary upgrading plants due to their high investment cost. Mobile membrane-based upgrading plants can help to reduce those investment costs for single operators and therefore, new valorisation routes become accessible to them. Performance of membrane-based upgrading plants is highly dependent on the chosen plant design. As mobile upgrading plants are limited to a maximum of two stages for the membrane separation due to space and weight restrictions, performance can be influenced mainly by operational conditions and membrane module characteristics. In this study, the influence of the membrane's CO2/CH4 selectivity on the performance of the mobile upgrading plant was investigated. Rising the CO2/CH4 selectivity from 25 to 38.51 and 50 increased the recovery and the biomethane purity to a level comparable to those of stationary membrane-based upgrading plants.

Biogas production as an element of sustainable development of rural areas in EU and Poland

The article is devoted to the issue of sustainable rural development, with particular focus on biogas. It presents legal regulations in this area used in the European Union, including Poland. Additionally, the article provides the results of operational tests (conducted in 2011-2012) of a small biogas plant with total capacity of two reactors 411 m 3 . The cost of electricity production was on the level of 113.76 PLN•MWh -1 and heat production costs - 206.06 PLN•MWh -1 . The construction cost of biogas plant was equal 1100 PLN per cubic meter. The exploitation costs of biogas plant were 42450 PLN•year -1 as the cumulative costs: the annual cost of installation maintaining 27 000 PLN•year -1 and cost of use of the biogas plant was 5450 PLN•year -1 . The calculated profit from the sale of produced electricity was 100622 PLN•year -1 . The calculation has been prepared in accordance with the level of prices in Poland in the years 2011-2012.

The use of agricultural waste for the renewable energy production

In addition to hydroelectric power plants, solar and wind power plants, biogas plants are important in the production of electricity and heat from renewable energy sources. It is known that depending on the type of substrate used for processing and the design features of biogas plants, they have their own advantages and disadvantages. Nevertheless, properly localized biomass installation is able to decrease the use of conventional materials reducing greenhouse gas emissions. Bio-waste, plant residues and other by-products can be used to produce electricity, heat and purified methane as fuel for repaired vehicles. Biogas production is a key technology for the sustainable use of agricultural biomass as a renewable energy source. Both, Poland and Ukraine, have a large agricultural area, and well developed animal cattery, which creates opportunities for alternative energy sources from biomass development.&#x0D; Agricultural biogas plant energy produced from waste such manure, slurry and another agricultural waste, is an excellent source of heat, likewise, electricity. Therefore the importance of using agricultural waste as an energy source in the production of biogas shall be emphasized. A significant drawback of the system is the need to provide low economic and environmental losses. For this purpose, the place of biomass harvesting, transport and its preparation together with storage should be taken into account. To achieve the highest efficiency, small biogas plants should have permanent composition of substrate consisting of various ingredients.&#x0D; Ukraine and Poland has considerable potential of renewable energy sources development of which can provide significant economic, ecological, and social benefits. The production of biogas has become an attractive source of extra income for many farmers. Biogas production has a useful effect not only on economic, but ecological development, particularly in the rural regions. At the same time, environmental protection aspects have gained additional importance, so that anaerobic treatment processes have become a key technology for environmental and climate protection.&#x0D; On the basis of the submitted documentation by the municipal administration and the manufacturer, the operation of biogas plants for the processing of organic agricultural waste in Gorajec and Odrzechowa (Poland) has been presented.

A Blockchain-based Architecture for Stable and Trustworthy Smart Grid

Smart Grid represents an efficient power transmission, distribution and management system. However, solutions for Smart Grid have raised security and privacy problems. Moreover, with the introduction of renewable energy resources, such as rooftop solar panels and small biogas plants, more and more electricity consumers are involved in the energy generation system. This may cause the power system unstable and/or the waste of the energy. Blockchain is a promising technology for solving these problems in the future energy system on account of its distributed trust, anonymity, data integrity and availability. In this paper, we propose a Blockchain-based architecture for Smart Grid. By using the proposed architecture, electricity consumers can be fully involved in the energy system and tracing the details of the energy they have consumed or generated. At the same time, the stability of the energy system can be kept, reducing the waste of the energy and potential hazard to the electrical equipment.

On the feasibility of on-farm biogas-to-electricity conversion: To what extent is solid oxide fuel cells durability a threat to break even the initial investment?

Despite their promising features, adverse economic feasibility still hamper SOFCs wide implementation and this effect is emphasized as long as the system size is reduced. According to previous investigations, the biogas pre-treatment section represents a burden for the economic viability. Aiming at reducing the extent of installation costs in SOFC-based configurations, biogas partial upgrading through CO2 gas-separation membranes is put forth as innovative solution against reforming. This innovative system concept is expected to make SOFCs more cost-effective, yet resulting feeding gas might cause a quicker SOFC performance decay. Besides solving this trade-off, the economic viability results strongly sensitive to subsidiary electricity prices in force according to the regulatory framework.This paper presents a comparative economic assessment regarding biogas-to-electricity conversion via Solid Oxide fuel cells (SOFCs) and mature technologies as internal combustion engines (ICEs). Results highlighted that, the innovative SOFC system is far more viable than reforming-based one, exhibiting a reasonable payback time, with an adequate subsidized electricity sale price (4 and 5 years for small/medium and large-size plants respectively when subsidy is 0.28 €/kWh), up to 1%1000h degradation rate. On the other hand, whilst considering a SOFC degradation rate of 0.03%1000h, the reforming-based system appears feasible only on large-size plants, yet recovering the initial capital expenditure in 9 years. Moreover, once the break-even point is reached, the gain in the net revenue produced by the innovative system is amplified in the event of small-size installation. This allows the possibility to undertake the risk of higher degradation rates (up to 2%1000h) without jeopardizing the economic profitability. Therefore, in the present regulatory framework and under current capital costs projections, the innovative SOFC system appears as much profitable as ICE mature technology. Such effort in the design of the fuel pre-treatment unit can lever SOFC broad spreading into the market of small biogas producers.

Application of small digester biogas for energy supply in rural areas

Village’s self-fulfillment of energy supply is a new concept being developed in Indonesia. Villages are expected to meet their own energy needs without relying on fossil-fuel and other non-renewable energy materials. The concept of village’s self-fulfillment of energy here includes two types of provision: the provision of electrical energy and the provision of bio-fuel by utilizing environmentally friendly renewable energy. Biogas is an alternative energy sources produced by anaerobic activities of organic materials such as human and animal feces, or domestic waste in rural communities. In general, rural farmers have 2-4 cows. It is assumed that cows/cattle produces ± 15 kg feces/head/day. A digester with 4m3 capacity potentially produces bio-gas per day that reaches 1.34 m3 equivalent to 6.30 kWh/day. This volume of bio-gas can be used for lamp lighting of 60-100 watts for 8 hours. Other applications that can be utilized are biogas stove. A family of farmer can use 2 stoves to cook 3 food recipes for 8 people and a generator for 1 hour. There is also potential solid mud of 40 kg that produces 8 kg of compost/day and potential sludge fluid as much as 160 liters including bio-urine of 32 liters/day. This paper discusses about the potency of small biogas digester application for village’s self-fulfillment of energy supply.

Embodied Energy Calculation of Small-Scale Biogas Plants in Rural Areas of Bangladesh

Installation of a biogas plant consumes a considerable amount of energy especially in transportation and manufacturing of various biogas plant construction materials. Energy conservation has become one of the important issues of today’s world for reducing greenhouse gases emission into the atmosphere and for reducing the costs of materials. This paper is focused on some issues relating to embodied energy in a biogas plant, particularly in the Bangladeshi context. Energy consumption in the production and transportation of basic biogas plant materials (such as brick, cement, sand etc.) and other materials used for construction has been discussed. Data has been collected from 20 small-scale biogas plants (2.4 m 3 , 3.2 m 3 , 4.8 m 3 ) located in different rural areas of Rajshahi, Bangladesh. It is found that the embodied energy of 2.4, 3.2 and 4.8 m 3 biogas plants are 9.4 GJ, 11.4 GJ, and 22.7 GJ respectively. Around 59-63% of total energy is costs by bricks, 29-33% by cement, 1.5% by sand, 3-5% by PVC pipe, 1% by HDPE pipe and 0.5% by steel used to install the plants. It is also found that the energy required for the production of the construction materials was 83-85% of total energy required while transportation energy was 16-17%. However, a complete analysis of energy input for the installation of a small scale biogas plant in Bangladesh has been described in this paper which will hopefully be helpful for further research in this sector.

Size, Subsidies and Technical Efficiency in Renewable Energy Production: The Case of Austrian Biogas Plants

This study estimates the efficiency of biogas plants and identifies determinants of inefficiencies. Data Envelopment Analysis is applied on a sample of 86 Austrian biogas plants for the year 2014, covering about one third of the installed electric capacity of Austrian biogas plants. We decompose technical efficiency into scale efficiency and pure technical efficiency (managerial efficiency). In a second-stage regression analysis the effects of subsidies and other variables on managerial efficiency are investigated. The main results are: i) 34% of biogas plants in our sample are technically efficient, 40% are scale efficient and 50% are managerial efficient; ii) small biogas plants (&lt;100 kW) are scale inefficient exhibiting increasing returns to scale; iii) production subsidies show a significant, negative relationship to managerial efficiency. The results are consistent with the hypothesis that production subsidies provide a disincentive to managerial effort of plant operators.

Eco-efficiency and entropy generation evaluation based on emergy analysis: Application to two small biogas plants

The research presented in this paper demonstrates how emergy analysis can be used to measure the eco-efficiency of unit operation processes (UOP). To illustrate this, two small biogas plants in France were analyzed, both with a nominal biogas production of almost 300 Nm3/d. One plant is an Upflow Anaerobic Sludge Blanket (UASB) digester treating dairy effluents while the other is a Continuous Stirred Tank Reactor (CSTR) farm biogas plant with a cogeneration of a nominal power of 45 kWe. The objectives of the study were to show: (a) the long-term sustainability of both UASB and CSTR biogas plants by assessing the respective eco-efficiencies using emergy analysis; (b) whether emergy analysis can holistically account for the true benefits of biogas plants; (c) how energy change or transformation is generated in any UOP systems. Energy analysis revealed some dysfunctions for both systems. The results show that it is possible to improve anaerobic digestion and efficiency of the process working on heat supply and insulation for the UASB-AD (anaerobic digester) plant and on insulation for the CSTR-AD plant. Emergy analysis of the UASB-AD plant through emergy ratios and indices confirm that eco-efficiency was not optimal due to a low biogas production and high sodium hydroxide consumption. For the CSTR, emergy indices show a better eco-efficiency than for the UASB with a biogas transformity close to 4 × 105 sej/Jbiogas in the same range as literature values. However, digester operation and maintenance should be upgraded as well as the use of digestate in order to improve the eco-efficiency of this kind of energy conversion system. The discussion chapter explores the applicability of emergy analysis to improve sustainability of UOP taking into account relationships between emergy, entropy generation and information theory. Entropy generation decreases after improving efficiency and sustainability, in accordance with the maximum empower principle.

Social Impact Assessment of the Biogas Production through Biomass for Bansuanmiang School under the Smart School Project

Small scale biogas plants were established at existing lands of seven small size schools at three provinces in lower northern part of Thailand. The successful experience of a small school at Khaonoi was used to implement this project, where food waste and animal dung have been used to produce biogas which replaced LPG used to cook lunch for students. After the successful implementation of project, these sites were used to train/ demonstrate the concerned from about 1,717 small size schools in target areas. The proposed project is conceived to open new venues in promoting and implementing Renewable Energy Technology. The establishment of university (R&amp;D) to school/ community(end user) relationship is very important aspect of the idea, which not only be perfect to implement the project smoothly but will create new ways to collect feedback and solve the issues immediately. Project sites being distributive in nature and community participated will act as a RE promotion hubs. The technology used is simple and all the materials involved are local. The project though has comparatively lower direct financial benefits, but has tremendous social,environmental and health related benefits. The reduction of CO2 and other GHG will not only be beneficial locally but will contribute in achieving the globally fixed targets. Community participation will be an added benefit to promote and expand the RE technologies among the masses over wide areas. The successful operation will be a strong message for visitors and the local community connected through their children with the school and hence project. The university level R&amp;D will get a way out for direct implementation and technology will be used for the betterment of communities and will participate in global efforts to reduce CO2 emissions as well.

Unlocking the Energy Potential of Manure—An Assessment of the Biogas Production Potential at the Farm Level in Germany

Residues from animal husbandry are one of the major greenhouse gas (GHG) emission sources in agriculture. The production of biogas from agricultural residues can reduce GHG emissions through an improved handling of the material streams such as manure storage. Additionally, biogas can substitute fossil energy carriers in the provision of heat, power, and transport fuels. The aim of this work is to estimate the manure potential for biogas production in Germany under the consideration of the farm size of livestock production. In Germany, cattle and pig farming is of major relevance with more than 130,000 farms throughout the country. To unlock the biogas potential of manure, the low energy density of manure, depending on the dry matter content, needs to be considered, meaning that biogas installations need to be built close to the manure production on the farm site. This not only results in a high number of biogas plants, but also due to the wide range of farm sizes in Germany, a huge number of very small biogas plants. Small biogas installations have higher specific investment costs. Together with the relatively low methane yields from manure, costs for power generation would be very high. Co-substrates with higher methane yield can lower the costs for biogas. Thus, the use of a co-substrate could help to use small manure potentials. Biogas plants with the necessary minimum size of 50 kWel installed power could be established at farms representing 12% of all cattle and 16.5% of all pigs respectively in Germany. Using excrement from pigs, farms representing 16.5% of the total amount of pigs could establish a biogas plant. The use of manure in combination with energy crops can increase the size of biogas plants on a farm site significantly. At cattle farms, the share would increase to 31.1% with 40% co-substrate and to 40.8% with 60% co-substrate. At pig farms, the share would increase to 36% if co-substrates were used.

Selected Problems of Small Biogas Fueled CHP Unit Design

The article presents selected problems related to the design and operation of small chp units used in individual biogas plants. There are presented and commented available design solutions that can match operational and cost-effective requests in relation to the engine, generator type selection, to design solutions of ignition system, fuelling system, waste heat utilization system and control unit. Presented solutions are discussed in terms of the unit reliability, power and heat generation efficiency and overall unit price. In conclusion, there are proposed some optimal design solutions for typical applications of small biogas fuelled chp units