Showing papers on "Biogas published in 2013"

Metal-organic frameworks for upgrading biogas via CO2 adsorption to biogas green energy.

Abstract: In the midst of the global climate change phenomenon, mainly caused by fossil fuel burning to provide energy for our daily life and discharge of CO2 into the atmosphere, biogas is one of the important renewable energy sources that can be upgraded and applied as a fuel source for energy in daily life. The advantages of the production of hybrid materials, metal–organic framework (MOF) adsorbents, expected for the biogas upgrading, rely on the bulk separation of CO2 under near-ambient conditions. This review highlights the challenges for MOF adsorbents, which have the greatest upgrading abilities for biogas via selective passage of methane. The key factors improving the ideal MOF materials for these high CO2 capture and selectivity uses for biogas upgrading to produce bio-methane and reduce fossil-fuel CO2 emission will be discussed.

Biogas upgrading – technology overview, comparison and perspectives for the future

Abstract: The utilization of biogas produced from organic materials such as agricultural wastes or manure is increasing. However, the raw biogas contains a large share of carbon dioxide which must be removed before utilization in many applications, for example, using the gas as vehicle fuel. The process – biogas upgrading – can be performed with several technologies: water scrubbing, organic solvent scrubbing, amine scrubbing, pressure swing adsorption (PSA), and gas separation membranes. This perspective presents the technologies that are used commercially for biogas upgradin g today, recent developments in the fi eld and compares the technologies with egard to aspects such as technology maturity, investment cost, energy demand and consumables. Emerging technologies for small-scale upgrading and future applications of upgraded biogas such as liquefied biogas are also discussed. It shows that the market situation has changed rapidly in recent years, from being totally dominated by pressure swing adsorption (PSA) and water scrubbing to being more balanced with new technologies (amine scrubbing) reaching significant market shares. There are significant economies of scale for all the technologies investigated, the specific investment costs are similar for plants with a throughput capacity of 1500 Nm3 raw biogas per hour or larger. Biogas production is increasing in Europe and around the globe, and so is the interest in the effi cient use of upgraded biogas as vehicle fuel or in other applications. The market for biogas upgrading will most likely be characterized by harder competition with the establishment of new upgrading technologies and further optimization of the mature ones to decrease operation costs. (Less)

Biogas from palm oil mill effluent (POME): Opportunities and challenges from Malaysia's perspective

Abstract: The generation of palm oil mill effluent (POME) alongside with the production of crude palm oil has created environmental issue for the palm oil mill industry in Malaysia due to its polluting characteristics. POME with its high organic content is a source with great potential for biogas production. However, POME is commonly treated using open ponding system just to comply with government regulation without capturing biogas released from the process. Biogas generated from anaerobic digestion of POME can replace palm kernel shell and mesocarp fiber which has higher economic value as boiler fuel; upgraded to be used in gas engine for power generation. It is estimated that net profit of RM 3.8 million per year can be obtained in a palm oil mill with processing capacity of 60 tonnes/hr from electricity generation using biogas produced from POME treatment. This review paper will elaborate on the potential of POME as a source of renewable energy and the challenges faced by the palm oil mills in Malaysia which deters the development of biogas plants in the mill.

Microbial community structure and dynamics during anaerobic digestion of various agricultural waste materials.

Abstract: The influence of the feedstock type on the microbial communities involved in anaerobic digestion was investigated in laboratory-scale biogas reactors fed with different agricultural waste materials. Community composition and dynamics over 2 months of reactors’ operation were investigated by amplicon sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Major bacterial taxa belonged to the Clostridia and Bacteroidetes, whereas the archaeal community was dominated by methanogenic archaea of the orders Methanomicrobiales and Methanosarcinales. Correlation analysis revealed that the community composition was mainly influenced by the feedstock type with the exception of a temperature shift from 38 to 55 °C which caused the most pronounced community shifts. Bacterial communities involved in the anaerobic digestion of conventional substrates such as maize silage combined with cattle manure were relatively stable and similar to each other. In contrast, special waste materials such as chicken manure or Jatropha press cake were digested by very distinct and less diverse communities, indicating partial ammonia inhibition or the influence of other inhibiting factors. Anaerobic digestion of chicken manure relied on syntrophic acetate oxidation as the dominant acetate-consuming process due to the inhibition of aceticlastic methanogenesis. Jatropha as substrate led to the enrichment of fiber-degrading specialists belonging to the genera Actinomyces and Fibrobacter.

A pyrosequencing-based metagenomic study of methane-producing microbial community in solid-state biogas reactor

Abstract: Background A solid-state anaerobic digestion method is used to produce biogas from various solid wastes in China but the efficiency of methane production requires constant improvement. The diversity and abundance of relevant microorganisms play important roles in methanogenesis of biomass. The next-generation high-throughput pyrosequencing platform (Roche/454 GS FLX Titanium) provides a powerful tool for the discovery of novel microbes within the biogas-generating microbial communities.

Transforming biogas into biomethane using membrane technology

Abstract: Upgrading biogas, i.e., the removal of CO2 from CH4 is an attractive regenerative energy as it is supplied continuously. Conventional upgrading techniques such as absorption or adsorption require significant amounts of energy and require equipment of large size. Hence, we give an overview on gas permeation membrane processes which are applied in biogas upgrading. Here, we consider the upgrading process as a whole. The multiscale design of membrane-based gas separation is analyzed in detail. Membrane materials, gas permeation modules and their respective operation as well as gas permeation processes for biogas upgrading are investigated. Applying gas permeation modules, compression of the feed gas should be used since it is energy efficient for gases with high amounts of CO2. Single stage gas permeation processes are not able to produce a high CH4 purity and simultaneously obtain a high CH4 recovery. Hence, multistage concepts are mandatory. Membrane-based upgrading systems are an interesting alternative to conventional biogas upgrading equipment and we expect that they will significantly contribute to the energy supply of the future.

Biogas upgrading - Review of commercial technologies

Abstract: Biogas production is growing and there is an increasing demand for upgraded bio- gas, to be used as vehicle fuel or injected to the natural gas grid. To enable the efficient use of biogas in these applications the gas must be upgraded, i.e. the carbon dioxide, which constitutes a large part of the raw biogas from the digester, must be separated from the methane. This report aims to evaluate the biogas up- grading technologies that are commercially available and in operation today: amine scrubbers, water scrubbers, PSA units, organic scrubbers and membrane units. The technologies are described in detail by presenting the theory behind the separation mechanism, the upgrading process as a complete system, operational issues and how these are solved, and finally the most important financial data. Furthermore, the best developed cryogenic technologies, which today are being used to purify landfill gas and biogas from some specific components and to lique- fy biogas, are presented. Cryogenic upgrading is an interesting possibility, but as this report shows, the technology still has some important operational issues to resolve. Technologies which are especially focused on small-scale applications are finally presented, however not in as much detail as the other, more common technologies. The report shows that for mid-scale applications, the most common options are all viable. The scrubbing technologies all perform well and have similar costs of investment and operation. The simplicity and reliability of the water scrubber has made this the preferred choice in many applications, but the high purity and very low methane slip from amine scrubbers are important characteristics. Regarding PSA and membrane units, the investment cost for these are about the same as for scrubbers. Furthermore, recent developments of the membrane units have also made it possible to reach low methane slips with this technology. Biogas production is increasing, in Sweden and globally, and the interest for bio- gas upgrading to utilize the gas as vehicle fuel or in other traditional natural gas applications increases as well. The mature technologies will see a market with more and harder competition as new upgrading technologies such as cryogenic upgrading are established, and other technologies optimize the processes to de- crease operation costs. Important issues for the future development of the biogas market relate to the implementation of new policy instruments. The work with the new European standard requirements for gas distributed through the existing gas grids is one issue that possibly can have a large effect on possibilities for distribu- tion of upgraded biogas. However, the future will most probably be fuelled by an increasing amount of upgraded biogas. (Less)

Co-digestion of manure and whey for in situ biogas upgrading by the addition of H 2 : process performance and microbial insights

Abstract: In situ biogas upgrading was conducted by introducing H2 directly to the anaerobic reactor. As H2 addition is associated with consumption of the CO2 in the biogas reactor, pH increased to higher than 8.0 when manure alone was used as substrate. By co-digestion of manure with acidic whey, the pH in the anaerobic reactor with the addition of hydrogen could be maintained below 8.0, which did not have inhibition to the anaerobic process. The H2 distribution systems (diffusers with different pore sizes) and liquid mixing intensities were demonstrated to affect the gas-liquid mass transfer of H2 and the biogas composition. The best biogas composition (75:6.6:18.4) was obtained at stirring speed 150 rpm and using ceramic diffuser, while the biogas in the control reactor consisted of CH4 and CO2 at a ratio of 55:45. The consumed hydrogen was almost completely converted to CH4, and there was no significant accumulation of VFA in the effluent. The study showed that addition of hydrogen had positive effect on the methanogenesis, but had no obvious effect on the acetogenesis. Both hydrogenotrophic methanogenic activity and the concentration of coenzyme F420 involved in methanogenesis were increased. The archaeal community was also altered with the addition of hydrogen, and a Methanothermobacter thermautotrophicus related band appeared in a denaturing gradient gel electrophoresis gel from the sample of the reactor with hydrogen addition. Though the addition of hydrogen increased the dissolved hydrogen concentration, the degradation of propionate was still thermodynamically feasible at the reactor conditions.