This thesis details the synthesis of over 100 new Type 3 porous liquids based on a broad range of microporous solids dispersed in electrically neutral solvents. These new porous liquids were ...successfully characterised and their physical properties including viscosity, density, disperision stability and their gas uptake capabilities explored. A particular porous liquid was highlighted as a potential drop in replacement for the upgrading of biogas to biomethane and further studies were carried out on this new porous liquid where it was found to perform over three times better than the current industrial scrubber in the upgrading of biogas. This thesis also discusses some interesting MOF based chemistry where the use of mechanochemistry allowed for the formation of defects which led to the MOFs having increased gas capacity and selectivity. The process of drug inclusion in MOFs were also investigated and the effects of using a size excluded solvent in the loading process cf. a standard wetting solvent was found to approximately double the amount of drug being loaded into the MOF. Lastly, new materials in the form of liquids with high compressibility were proposed and studied. These liquids exhibit high compressibility and the reasons for the compressibility along with investigating some surrounding factors were explored.
As one of the important biomass energy sources, biogas construction plays a vital role in rural development. The last three decades have witnessed a strong promotion of household-based decentralized ...biogas system in China. Nevertheless, the government explicitly has a strong preference for large-scaled centralized biogas system, as the focuses of recent related polices have been shifted to it from decentralized system. Under this circumstance, this paper reviewed the development status of both decentralized and centralized biogas systems, described the limitations of decentralized biogas system in recent rural development and overviewed the changes in related policies supporting rural biogas construction. Based on these analyses, the perceptional, institutional, financial, technical and regional constraints are found out to be the five main constraints that hinder the upgrade of the biogas system. This paper suggests that balancing the development between the two biogas systems promoting the industrialization, commercialization and comprehensive utilization of biogas, and increasing household education should be attached more importance in future rural biogas policies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•Applications of diverse membrane systems in biogas production, upgrading and conversion are presented.•Various membrane materials, configurations and processes along with their ...performance and notable features are analyzed.•Extensive experimental attempts at laboratory, pilot, semi-industrial and industrial scales are included in discussions.•Benefits and opportunities for integration of membranes in hybrid configurations for biogas upgrading are outlined.•Trends in biogas conversion are delineated by highlighting the contributions of membranes in methanation and hydrogenation processes.•Guidelines for the design, integration, and optimization of efficient and economic membrane units for biogas processing are provided.
Biogas serves a reliable renewable resource and energy carrier with growing potentials based on the number and size of plants in operation and planned for future. The technical viability of membranes for biogas valorization has attracted attention towards further advancements from the materials and process perspectives. The present review aims to meticulously analyze the extensive works carried out at laboratory, pilot, semi-industrial and industrial scales pertinent to biogas with the aid of membrane separation processes. Discussions are devoted to the performance characteristics and specifications of various membrane materials, processes and configurations employed spanning the entire value chain of biogas production, upgrading and conversion. These include recovery of dissolved methane and liquids (water, ammonia) at the production stage, as well as exploitation of semipermeable and gas–liquid membranes such as membrane contactors, membrane reactors and membrane bioreactors for upgrading of raw biogas to achieve quality biomethane. Besides, valuable experiences in integration of membranes in hybrid configurations for biogas upgrading are evaluated. Also, the emerging trends in biogas conversion are delineated by focusing on methanation and hydrogenation with the aid of membranes. Finally, guidelines for the design, integration and optimization of high-performance membrane systems are set by taking into account the economic considerations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
In the anaerobic digestion (AD) process there are some difficulties in maintaining process stability due to the complexity of the system. The variability of the raw material coming to the facility, ...temperature fluctuations and pH changes as a result of microbial processes cause process instability and require continuous monitoring and control. Increasing continuous monitoring, and internet of things applications within the scope of Industry 4.0 in AD facilities can provide process stability control and early intervention. In this study, five different machine learning (ML) algorithms (RF, ANN, KNN, SVR, and XGBoost) were used to describe and predict the correlation between operational parameters and biogas production quantities collected from a real-scale anaerobic digestion plant. The KNN algorithm had the lowest accuracy in predicting total biogas production over time, while the RF model had the highest prediction accuracy of all prediction models. The RF method produced the best prediction, with an R2 of 0.9242, and it was followed by XGBoost, ANN, SVR, and KNN (with R2 values of 0.8960, 0.8703, 0.8655, 0.8326, respectively). Real-time process control will be provided and process stability will be maintained by preventing low-efficiency biogas production with the integration of ML applications into AD facilities.
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•Industrial Scale anaerobic digestion plant data were collected.•5 different ML algorithms were used to predict biogas production.•The best prediction was achieved with the RF algorithm (R2 = 0.9242).•The model with the lowest R2 value (0.8326) was the SVR algorithm.•Process stability could be maintained with ML applications in AD plants.
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Biogas is a renewable energy resource that can play a leading role in the sustainable energy transition through green electricity generation. Biogas can be converted to electricity and renewable ...fuels through different technologies and prime movers. Prime movers that can be used for biogas power generation include gas and steam turbines, diesel engines, Otto cycle engines, Stirling engines as well as direct conversion in fuel cells. Since biogas has high octane rating, it can be used directly or with minimal modifications in spark ignition or petrol engines, but needs several modifications for use in dedicated diesel biogas engines or dual fuel engines and bi engines. The dual fuel mode which uses biomethane or biogas and diesel requires little or no engine modifications unlike the conversion to a dedicated gas engine. The performance of biogas prime movers is greatly enhanced if enriched biogas or biomethane is used in place of raw biogas. Other than use in various engines, biogas can be cleaned and used in fuel cells and manufacture of renewable hydrogen. As renewable natural gas, biogas in the form of biomethane can be injected to the natural gas grids for domestic and industrial application as natural gas substitute in applications which include power generation.
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Biogas is an important renewable biomass energy source. Currently, China's biogas production is one of the highest globally, with 12.366 G m3 of gas being produced, which can improve the energy ...structure of rural areas in China. China's biogas plants have undergone rapid development in the last 10 years. From 2008 to 2017, the number of biogas plants has increased 2.76 times. In addition, the biogas production contribution of biogas plants to whole national biogas production has increased from 5.88% in 2008 to 21.09% in 2017. The development of large-scale agricultural residues biogas plants has been fast, with good benefits. China's biogas production has huge potential. According to the estimates, the total biomass of crop straws in China in 2017 was 1.158 G t, and the total amount of livestock and poultry manure was 1.788 G t. In addition, invasive plants with large biomass can undergo co-fermentation, converting waste into a valuable resource. However, electricity generation utilizing biogas is still in the initial stages. In 2017, the installed capacity of biogas grid-connected electricity generators in China was 500 M W, and the electricity generation potential is large. The oriented field of China's biogas development includes the development of large-scale biogas plants (biomethane plants), biogas electricity generation grid plants, household biogas digesters, and small-scale biogas digesters in poor mountainous areas; the integrated use of biogas digestate; construction of diverse capital investment mechanisms; and incentives to improve the biogas industry.
•China's biogas production is one of the highest globally.•China's biogas production from crop straws and livestock manure has huge potential.•The installed capacity of biogas grid-connected electricity generators in China was 500 M W.•Policies and challenges of biogas development in China are discussed.
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Anaerobic digestion (AD) is a multipurpose technology. One of the AD outcomes is biogas that can be used to supply a local thermal demand, electricity generation or upgraded to fuel vehicle. Brazil ...has the largest potential for producing biogas, due to its extensive agroindustrial production plus the fact that the country has a population of over 210 million inhabitants. The Brazilian Association of Biogas and Biomethane (ABiogás) reports a potential biogas production of 41.4 billion m3 per year in the sugar-energy sector. However, less than 2% of this is achieved, indicating that the biogas is still chemically, economically, and politically invisible. The current technologies for the production, purification and end-use of biogas/biomethane were reviewed and presented in the context of sugarcane biorefineries. One of the major findings has indicated a thermal efficiency of 85% and a national grid surplus of 74–121 kWh.ton−1 sugarcane when steam boilers connected to electricity generators are used. Alternatively, a quarter of the vinasse generated by a medium-size sugarcane mill (600 m3 d−1) would be enough to supply the diesel consumption of on agricultural operations. The motivation of this review came from the fact that normally renewable energy does not reach its potential due to the lack of references on technological, regulatory and management in their productive arrangements: essential aspects to make them feasible. Therefore, it is expected to strengthen the panorama of research in the biogas system to properly fit with the current expansion and diversification of the Brazilian energy matrix.
•Covered lagoons in sugarcane mills represent a mature technology.•Biogas/Biomethane remains a significantly under-exploited renewable energy resource in Brazil.•Biogas value chains generate economic returns via planning, implementation and O&M services.•Biofertilizer is a co-product of anaerobic digestion and must be considered in the circular economy and nutrients cycles.•Biogas/Biomethane end-use requires a systematic study of spatial and logistical.
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This article reports the results of a discrete choice experiment with 183 German biogas plant operators designed to elicit the respondents' plans for biogas utilization pathways after the end of ...guaranteed feed‐in tariffs. Participants could choose between ‘flexibilization’ for demand‐based electricity generation and conversion to biomethane upgrading for direct feed‐in into the natural gas grid. A binomial logit model revealed a 37% probability of switching to biomethane upgrading. These plants are characterized by higher capacities, several involved shareholders, secured succession, costly digestate disposal and belonging to the upper performance quartile. Mixed logit estimations conducted separately for the two investment concepts revealed a very high overall willingness to invest: 71% for flexibilization and 82% for biomethane upgrading. The respondents demand a return on investment of 19% for flexibilization and 26% for biomethane upgrading. Within the flexibilization, twofold overbuilding (installed capacity equals 2 times the rated power) is clearly preferred to fivefold overbuilding. For the biomethane upgrading, private ownership of the upgrading plant is preferred to a joint investment in a central upgrading facility. Limiting the use of energy crops reduces the propensity to invest in both models, while a longer utilization period enhances it. The respondents consider lack of planning reliability as the biggest obstacle to invest, followed by long approval procedures and high investment costs due to restrictive legal requirements.
The article presents findings from a discrete choice experiment involving 183 German biogas plant operators regarding their preferences for post‐feed‐in tariff operation. The study found a 37% probability of switching to biomethane upgrading, strong investment willingness (71% for flexibilization, 82% for biomethane upgrading), and specific preferences such as twofold overbuilding and private ownership, while major obstacles included planning reliability, lengthy approvals, and high legal costs.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Enriching biogas with hydrogen could enable conventional natural gas systems to be used for clean energy. This technique has generally been evaluated using laboratory devices, so this study addresses ...a conventional combustion system, consisting of a 100 kW burner fed with biogas-hydrogen mixtures instead of natural gas. Flame behavior and ignition behavior were investigated. The flame structure was analyzed by infrared thermography. The tests were performed with three different mixtures of CH4–CO2 recreating an energetically rich biogas, 30% CO2 (BG70), standard biogas 40% CO2 (BG60) and poor biogas 50% CO2 (BG60). Then, each biogas type was enriched with hydrogen up to 20%. Major improvements were obtained between 5% and 10% hydrogen composition since the flame stability increases considerably. Flame structure closest to natural gas flame was achieved for BG60 and BG70 at 10% H2. However, the flame temperature remained lower than that of natural gas in all cases.
•Increased CO2 decreases the reduction zone of flame and increases flame suppression.•Reduction zone has a greater impact on the flame temperature, increasing with H2.•Flame structure of biogas enriched with 10% H2 resembles the flame of natural gas.•The temperature for the same flame structure varies depending on the fuel composition.•Commercially available natural gas burners are capable of burning H2-enriched biogas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
The volume of biogas produced in agricultural areas is expected to increase in coming years. An increasing number of local and regional initiatives show a growing interest in decentralized energy ...production, wherein biogas can play a role. Biogas transport from production sites to user, i.e. a CHP, boiler or an upgrading installation, induces a scale advantage and an efficiency increase. Therefore the exploration of the costs and energy use of biogas transport using a dedicated infrastructure is needed. A model was developed to describe a regional biogas grid that is used to collect biogas from several digesters and deliver it to a central point. The model minimizes transport costs per volumetric unit of biogas in a region. Results are presented for different digester scales, different sizes of the biomass source area and two types of grid lay-out: a star lay-out and a fishbone lay-out. The model shows that transport costs in a fishbone lay-out are less than 10 €ct m−3 for a digester scale of 100 m3 h−1; for the star lay-out costs can go up to 45 €ct m−3. For 1800 m3 h−1 digesters, these values are 4.0 €ct m−3 and 6.1 €ct m−3, respectively. The results indicate that cooperation between biogas producers in collecting biogas by means of a fishbone lay-out reduces the biogas transport costs relative to using a star lay-out. Merging smaller digesters into a smaller number of larger ones reduces the costs of biogas transport for the same biomass source area.
•A model of a biogas grid infrastructure was developed.•The model describes the collection of biogas from a surrounding area to a hub.•The costs of biogas transport are lower for large digesters in a biogas grid.•Cooperation by means of a fishbone lay-out results in lower biogas transport costs.•The use of a fishbone lay-out does not necessarily result in higher direct energy use.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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