云南省沼气及其综合利用发展预测与分析

云南省气候适宜,农村有机废弃物丰富,是以展沼气的理想区域．沼气综合利用前景广阔,沼气发酵系统与农业相结合,能使农业的发展容能源、经济、社会和生态效益为一体,有力地促进农村经济的发展,是我国农业奔小康的理想途径之一．针对云南省沼气发展现状,在对沼气及其综合利用发展预测与分析的基础上,对云南省发展沼气提出一些看法     

牧原沼气工程沼液余热回收工艺的热力学性能及经济分析

针对我国大中型沼气工程所存在的系统热量利用不合理等问题,以河南省南阳市内乡牧原日产10 000 m³粪污资源化处理沼气示范工程为例,对沼气工程沼液余热回收工艺进行研究,分析其系统热力学性能及经济性能。计算结果表明,秋冬季节该沼气工程热能需求量约为7.77×10⁴～1.09×10⁵MJ,其中,99.5%用于系统增温。同时,对比分析了采用传统的沼气锅炉供热、沼气锅炉与系统余热回收联用供热两种供热方式的系统能耗后发现,沼气锅炉与余热回收联用可以大大降低沼气锅炉用气量,仅为传统工艺耗气量的20%～35%,可使更多的沼气用于发电。此外,还对系统进行了热力学评价,沼气锅炉与系统余热回收联用可使系统总■效率提升8%～13%,秋冬季节利用余热回收可以节省沼气、增加发电量,为11 940～15 525 k W·h,每天可产生经济效益为5 970～7 762元。     

试论户用沼气池建设的节能减排和农民增收效果

近年来我国逐渐加快了农村发展的步伐,沼气工程作为新农村发展中的一项重要举措,不仅能够有效解决农户的能源问题,还能够有效带动农民种植业、养殖业的发展,是我国新农村建设中的重要内容。本文将对当前沼气能源和农业生产效益进行分析。     

2009年我国将在13个省试点秸秆沼气集中供气

2009年,我国将在黑龙江、内蒙古、天津、河北、河南、山东、山西、陕西等13个省（市、自治区）进行秸秆沼气集中供气项目试点。在全国秸秆沼气试点项目座谈会上对《秸秆沼气集中供气试点项目可研评审办法（试行）》（征求意见稿）进行了修改。来自农业部规划设计研究院、北京化工大学等单位的5位专家在座谈会上提交了5份秸秆沼气试点专业项目申请书以供选择,原则上每个试点省仅支持一项。     

沼气发酵菌的富集培养和应用

1972年以来,我省农村大办沼气的群众运动蓬勃发展,许多生产队、生产大队和人民公社已基本实现沼气化。在大办沼气的群众运动中,我们开展了沼气发酵菌的研究工作。活性污泥的选择为了提高沼气产量并加速产气以及增加沼气中的甲烷成分,我们采集了沼气较多的活性污泥,经富集培养,选取产气量和沼气中甲烷含量较高的污泥作为“菌     

中国农业生物质能发展现状与展望

我国农业生物质能资源丰富,分布广泛,近年来,我国的生物质能开发利用取得了一定的成绩,沼气产业发展成熟,已经形成102万吨燃料乙醇的生产能力,开发了甜高粱茎秆等非粮作物生产燃料乙醇的技术储备,生物质发电技术进行了示范,利用技术基本成熟,发展潜力巨大。良好的宏观政策环境逐渐形成,未来我国农业生物质能的发展重点是固体成型燃料、沼气和能源作物。[编者按]     

基于生命周期的户用沼气系统可用能核算——以广西恭城瑶族自治县为例

发展沼气生态农业可以实现资源的综合利用,带来经济效益与生态效益,同时解决我国农村地区能源短缺和环境污染问题。明确沼气系统内部的物质能量转化利用情况,可为沼气农业系统优化和效益提升提供科学依据。提出基于生命周期的户用沼气系统可用能核算方法,并以全国生态农业示范县——广西恭城瑶族自治县为例,核算了该县典型户用沼气系统建设、运行和利用单元投入产出的可用能流,分析了整个系统的可用能转化与利用效率。结果表明:系统的可用能投入为(1.06×108)kJ/a,可用能产出为(5.00×107)kJ/a,主要产出形式为沼渣;可用能转化率为48.82%,利用率为21.60%,其中沼气利用效率最高;系统产生的环境排放为(3.42×105)kJ/a,主要形式为系统利用单元沼气燃烧产生的CO2。由此可见,沼气生态农业可通过增加转化环节实现农业废弃物的再利用,系统可用能效率具备极大的提升空间,系统可持续性有待加强。可以考虑从改进工艺技术和改善发酵环境两方面提高户用沼气系统能量转化的能力,通过沼渣沼液综合利用技术方面的创新提高户用沼气系统的可用能利用效率。生命周期可用能核算方法可以更全面的反映系统的能量利用效率,便于诊断薄弱环节,为系统优化提供依据。     

沼气炉和沼气灯的土法制造

沼气炉沼气炉由进气孔、气体混合室、喷火口等部分组成。用沼气煮饭、炒菜,既要求炉温高,又要求节省沼气。所以在制作和使用沼气炉时,应该摸索沼气炉各个方面的关系,掌握它的规律。一、制作和使用沼气炉的注意事项1.空气混入比例:根据计算,1个体积的沼气(指普通人工制取沼气),要与7个体积的空气相混合,才能充分燃烧。在使用中,燃烧前混合进去的空气要低     

谈谈沼气发酵

在毛主席革命路线指引下,我国大办沼气的群众运动象雨后春笋一样,蓬勃发展起来.仅我省就有40多个公社、200多个生产大队和近2,000个生产队基本实现了沼气化。许多社员家庭做到了“煮饭不用柴和炭,点灯不用油和电”。     

国内简讯

全国最大沼气发电厂并网发电 2009年5月19日,全国最大的沼气发电厂——德青源沼气发电厂建设工程竣工,正式并网发电。德青源北京生态园是目前亚洲单场存栏最大的优质鸡蛋生产基地,存栏蛋鸡210万只、雏鸡90万只,整个生态园每天产生鸡粪210余t,排出生产、生活污水270余t。为了解决这些问题,德青源采用世界一流的生物发酵技术和燃气发电技术,将所有鸡粪和污水收集起来,生产沼气用于发电,从而真正实现了整个生态园区废水废物的零排放,成功解决了这一长期以来制约我国大型养殖基地建设和发展的大难题。     

Effects of mixing system and pilot fuel quality on diesel–biogas dual fuel engine performance

This paper describes results obtained from CI engine performance running on dual fuel mode at fixed engine speed and four loads, varying the mixing system and pilot fuel quality, associated with fuel composition and cetane number. The experiments were carried out on a power generation diesel engine at 1500 m above sea level, with simulated biogas (60% CH₄–40% CO₂) as primary fuel, and diesel and palm oil biodiesel as pilot fuels. Dual fuel engine performance using a naturally aspirated mixing system and diesel as pilot fuel was compared with engine performance attained with a supercharged mixing system and biodiesel as pilot fuel. For all loads evaluated, was possible to achieve full diesel substitution using biogas and biodiesel as power sources. Using the supercharged mixing system combined with biodiesel as pilot fuel, thermal efficiency and substitution of pilot fuel were increased, whereas methane and carbon monoxide emissions were reduced.     

Advanced Multi‐Fuelled Solid Oxide Fuel Cells (ASOFCs) Using Functional Nanocomposites for Polygeneration

An advanced multifuelled solid oxide fuel cell (ASOFC) with a functional nanocomposite was developed and tested for use in a polygeneration system. Several different types of fuel, for example, gaseous (hydrogen and biogas) and liquid fuels (bio‐ethanol and bio‐methanol), were used in the experiments. Maximum power densities of 1000, 300, 600, 550 mW cm^?2 were achieved using hydrogen, bio‐gas, bio‐methanol, and bio‐ethanol, respectively, in the ASOFC. Electrical and total efficiencies of 54% and 80% were achieved using the single cell with hydrogen fuel. These results show that the use of a multi‐fuelled system for polygeneration is a promising means of generating sustainable power.     

On-site removal of H<Subscript>2</Subscript>S from biogas produced by food waste using an aerobic sludge biofilter for steam reforming processing

H₂S in biogas was removed by sludge-loaded biofiltration, rendering the biogas suitable for catalytic reforming into a mixture of CO and H₂ syngas that was then applied for the generation of electricity using a solid oxide fuel cell or for the chemical synthesis of methanol. The biogas was anaerobically produced in a 2 m³ bioreactor at 35°C for 2 years using restaurant food waste from Korea Advanced Institute of Science and Technology (KAIST), and the concentration of H₂S in the biogas ranged from 612 to 1,500 ppmv (Avg. 1,060 ppmv). Two immobilized cell bioreactors 0.2 and 8.5 L in volume were loaded with aerobic sludge and used to study characteristics of H₂S removal from biogas. At a retention time of 400 sec, the removal efficiency of H₂S was over 99% following initial stabilization for 7 days in the 8.5 L bioreactor installed at the on-site biogas facility. The maximum rate of H₂S removal in this study was 359 g-H₂S/m³/h with an average mass loading rate of 14.7 g-H₂S/m³/h (kinetic analysis: V _m = 842.6 g-H₂S/m³/h and K _s = 2.2 mg/L). Therefore, purified biogas with a negligible concentration H₂S was efficiently reformed to syngas. This study demonstrates the feasibility of biogas purification as a part of high-quality syngas production.     

Biogas plants for small farms in Kenya

This paper reports on the authors' efforts to improve the small farm community welfare in Kenya by promoting biogas technology. The survey showed that fuel was used in Kenyan farms mainly for cooking and lighting, and wood, crop residue, and charcoal were the predominant fuel sources. Mostly women collected firewood, fetched water, and cooked. Building a fire with these fuels was time-consuming, and smoke from these fires was damaging to the living environment. Hence, applying biogas technology to Kenyan small farms not only guarantees a reliable, renewable energy source, but also provides other benefits, such as cleaner household environments, better working conditions for housewives,     

Phycoremediation coupled production of algal biomass,harvesting and anaerobic digestion: Possibilities and challenges

Biogas produced from anaerobic digestion is a versatile and environment friendly fuel which traditionally utilizes cattle dung as the substrate. In the recent years, owing to its high content of biodegradable compounds, algal biomass has emerged as a potential feedstock for biogas production. Moreover, the ability of algae to treat wastewater and fix CO₂ from waste gas streams makes it an environmental friendly and economically feasible feedstock. The present review focuses on the possibility of utilizing wastewater as the nutrient and waste gases as the CO₂ source for algal biomass production and subsequent biogas generation. Studies describing the various harvesting methods of algal biomass as well as its anaerobic digestion have been compiled and discussed. Studies targeting the most recent advancements on biogas enrichment by algae have been discussed. Apart from highlighting the various advantages of utilizing algal biomass for biogas production, limitations of the process such as cell wall resistivity towards digestion and inhibitions caused due to ammonia toxicity and the possible strategies for overcoming the same have been reviewed. The studies compiled in the present review indicate that if the challenges posed in translating the lab scale studies on phycoremediation and biogas production to pilot scale are overcome, algal biogas could become the sustainable and economically feasible source of renewable energy.     

Weed Seed Survival during Anaerobic Digestion in Biogas Plants

Anaerobic digestion using animal manure and crop biomass is increasingly being used to produce biogas as a durable alternative to fossil fuel. The sludge, the leftover after processing, is returned to the field as a crop fertilizer. If weed seeds survive anaerobic digestion, the use of contaminated sludge poses a phytosanitary risk. The conditions that seeds are likely to encounter in biogas plants, and the effect of these, in particular temperature, on seed viability were reviewed. Knowledge on seed defence mechanisms and how these might protect seeds from inactivation in biogas reactors was summarized. Mechanisms of seed inactivation can be classified as thermal, biological and chemical. Weed species with hard seeds (physical dormant), high thermoresistance, a thick seed coat or adapted to endozoochory were identified as high-risk species. Specific seed traits could be used in future tests to circumvent extensive testing of seeds in biogas reactors.     

Life cycle assessment of biogas infrastructure options on a regional scale

A life cycle assessment has been completed of potential biogas infrastructures on a regional scale. Centralised and distributed infrastructures were considered along with biogas end uses of Combined Heat and Power (CHP) and injection to the gas grid for either transport fuel or domestic heating end uses. Damage orientated (endpoint) life cycle impact assessment method identified that CHP with 80% heat utilisation had the least environmental impact, followed by transport fuel use. Utilisation for domestic heating purposes via the gas grid was found to perform less well. A 32% difference in transportation requirement between the centralised and distributed infrastructures was found to have a relatively small effect on the overall environmental impact. Global warming impacts were significantly affected by changes in methane emissions at upgrading stage, highlighting the importance of minimising operational losses.     

Biogas technology in sub-Saharan Africa: status, prospects and constraints

Africa is a continent with abundant, diverse and un-exploited renewable energy resources that are yet to be used for improving the livelihood of the vast majority of the population. The production of biogas via anaerobic digestion of large quantities of agricultural residues, municipal wastes and industrial waste(water) would benefit African society by providing a clean fuel in the form of biogas from renewable feedstocks and help end energy poverty. Biogas technology can serve as a means to overcome energy poverty, which poses a constant barrier to economic development in Africa. Anaerobic digestion of the large quantities of municipal, industrial and agricultural solid waste in developing countries present environmental conditions that make use of anaerobic biotechnology extremely favourable under perspective of sustainable development. However, the use of biogas is not widespread in Africa. There are many reasons of economic, technical and non-technical nature for the marginal use of biogas in Africa. The key issue for biogas technology in Africa is to understand why large scale-up has not occurred despite demonstration by several programmes of the viability and effectiveness of biogas plants. This article provides knowledge-based review of biogas technology status, constraints and prospects in Africa. In addition, recommendations to overcome the technological and non-technological challenges to commercialise biogas are discussed. Recommendations for large scale adoption for biogas technology include establishing national institutional framework, increasing research and development, education and training and providing loans and subsidies and major policy shift in the energy sector. The conclusion is that biogas technology must be encouraged, promoted, invested, researched, demonstrated and implemented in Africa.     

Biogas production: current state and perspectives

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield.