农村户用沼气技术(1)

自从生态家园富民计划实施以来，广大农民朋友参与生态农业建设的热情很高，也有一些农民朋友修建了沼气池以后发现问题却不知道怎么办。本刊以问答形式向广大读者介绍一些农村家用沼气技术的基本常识。[编者按]     

农村户用沼气技术(3)

第三集 沼气池管理技术 本集重点介绍农村家用沼气池管理方面的技术。 35问：建好沼气池以后如何管理好是非常重要的事情，那么，沼气池的管理都包括些什么呢？     

农村户用沼气技术(2)

第二集如何建造家用沼气池 本集重点介绍沼气池的建造技术，以及在修建沼气池过程中所遇到的问题的处理方法。     

专业化配套是农村户用沼气建设的必然要求

随着国债农村户用沼气项目的进行，各地呈现出建设沼气的热潮。2004年，全国新增农村沼气户103万户，如此大规模的建设，配套产品的质量显得尤为重要。根据设计要求，混凝土沼气池使用寿命为20a，配套产品的设计寿命也应为20a，才能实现真正的配套，尤其是与混凝土紧密结合的导气管、地埋的输气管等不易更换的配件的质量，直接影响沼气池的使用寿命。如何保证沼气池的设计使用寿命，笔者认为，专业化配套是农村户用沼气发展的必然要求。     

关于户用沼气系统服务体系物业化管理模式推广和普及的构想

农业部推广的“生态家园富民工程”，探索出了一条农村可持续发展的新思路，同时也给众多专注于农村沼气新技术和新产品的研发、生产的企业提供了发展机遇。作为农村可再生能源领域的专业化公司，如何与各级能源部门通力合作，保证农村户用沼气系统长期有效的运行，使之成为农民致富的新动力，带动户用沼气新技术和新产品的良性发展，是可再生能源企业义不容辞的社会责任。     

渭河上游黄土丘陵地区农村户用沼气建设的环境经济效益分析

渭河上游的黄土丘陵地区经济贫困、环境脆弱、生活能源短缺,生物质的过量消费成为生态环境退化的重要因素。文章通过问卷调查获取相关数据,并建立计量模型,评估户用沼气建设工程对农户生活能源总体结构的影响,进而分析其生态经济效益。结果表明,沼气对农户生活能源结构的转换升级作用明显,生态经济效益显著,每口8 m3沼气池年产气量为300 m3,每年创造生态经济效益591.32元,其中生态环境效益231.88元,经济效益359.44元,减少农户现金支出153.39元。     

应用沼气技术 建设生态家园——西部农村实施富民计划的技术思路及可行性探讨

从理论与实践的角度,探讨了西部农村实施生态家园富民计划的技术思路及其可行性。提出以沼气技术为纽带,充分发挥“一气”(沼气)带“三料”(燃料、肥料、饲料)、“三料”促“五业”(农、林、牧、副、渔)、“五业”出“效益”(经济、生态、社会效益)的发展思路。     

农村户用沼气对环境影响的指标体系与评价

以客观性、系统性、定量性、比较性、效益性为原则,采用属性逐层分解法,建立农村户用沼气的环境评价指标体系,利用层次分析法对户用沼气对环境的影响进行评价,得出结论:农村户用沼气对各项环境指标的影响均为正或为零,各项指标影响程度由弱到强依次为大气环境(0)或水资源(0)、土地质量(0.034)、农村居民的健康状况(0.045)、动植物资源(0.2405)、农村居民的居住环境(0.6975)、农村居民的生活条件(1.1417);农村户用沼气对农村社会环境的影响程度(2.16)远大于对自然环境的影响程度(0.2755);农村户用沼气对环境影响的综合评价值为2.4355,达中度有利影响。     

户用沼气系统运行效果的技术评价指标体系

用层次分析法构建了户用沼气系统的技术评价指标体系,通过德尔菲法构建了评价指标的判定方法学,从而为评价户用沼气系统的运行效果提供理论依据和技术支撑。将户用沼气系统分为5个子系统:构筑物系统、产气系统、沼气输送系统、沼气利用系统、沼液沼渣处理系统。将此评价体系用于评估某国户用沼气系统的运行效果,结果表明,如果仅以正常产气衡量,则正常运行的概率为76%;如果综合考虑沼气系统各个方面,则运行良好的概率仅为1%。     

中国农村户用沼气生产及其影响因素分析

对我国农村沼气生产情况进行了分析,认为我国农村沼气生产在取得较快发展的同时,存在较大的地区差异.文中采用面板数据对农村沼气生产影响因素进行分析,指出我国农村沼气生产明显受到该地区大牲畜存栏数量、平均温度、农户收入水平以及制度和技术进步因素的影响,而农户人均受教育程度和沼气的替代能源价格等因素对沼气生产的影响并不明显.     

A decision support system for technologies of rural electrification

An interactive computer program has been developed to determine and to evaluate the optimal design of electricity distribution systems in rural areas. The program considers the costs and benefits of grid electrification, isolated diesel generators and centralized photovoltaics. It provides support for decisions on choices of technology. The program optimizes within the context of long-term load and system expansion; it runs on a 384K CPU microcomputer.     

A survey of renewable energy technologies for rural applications

The availability of modern energy has long been recognized as one of the requirements for rural economic development. The recent advances that have been made in renewable energy technologies have broadened their applicability despite the recent decline in world oil prices. In this paper, we summarize the technology status of renewable energy technologies (photovoltaics, wind energy, hydro, and biomass technologies) that are considered appropriate for rural areas. In addition, we discuss the economic and institutional constraints that inhibit their widespread dissemination in rural areas.     

Biogas/photovoltaic hybrid power system for decentralized energy supply of rural areas

Biomasses created from natural resources such as firewood, charcoal and forest crops are still the main source of energy in many communities in the developing countries of the world. The absence of modern techniques, in terms of energy conversion and the lack of resource planning, places a great burden on the environment, not only in terms of deforestation but the polluting residual emissions created by the burning of such fuels. Even in some developed countries, it is possible to find rural areas that have no access to the conventional national electrical grid. The lack of this facility is detrimental to the social and economic development of any country or community. Renewable energy systems have been used in many cases to mitigate these problems. The present paper introduces the concept of an alternative Hybrid Power System configuration that combines photovoltaic modules and digesters fuelled by goat manure as the basis for rural sustainable development. Attention is drawn to the Northeast Region of Brazil, one of the largest semi-arid regions in a single country. The regional conditions of Northeast of Brazil are not unique, suggesting that other countries of a similar nature would benefit from the same energy system.     

Biogas production from municipal sewage sludge (MSS)

Biogas is produced by anaerobic (oxygen free) digestion of organic materials such as sewage sludge, animal waste, and municipal solid wastes (MSW). As sustainable clean energy carrier biogas is an important source of energy in heat and electricity generation, it is one of the most promising renewable energy sources in the world. Biogas is produced from the anaerobic digestion (AD) of organic matter, such as manure, MSW, sewage sludge, biodegradable wastes, and agricultural slurry, under anaerobic conditions with the help of microorganism. Biogas is composed of methane (55–75%), carbon dioxide (25–45%), nitrogen (0–5%), hydrogen (0–1%), hydrogen sulfide (0–1%), and oxygen (0–2%). The sewage sludge contains mainly proteins, sugars, detergents, phenols, and lipids. Sewage sludge also includes toxic and hazardous organic and inorganic pollutants sources. The digestion of municipal sewage sludge (MSS) occurs in three basic steps: acidogen, methanogens, and methanogens. During a 30-day digestion period, 80–85% of the biogas is produced in the first 15–18 days. Higher yields were observed within the temperature range of 30–60°C and pH range of 5.5–8.5. The MSS contains low nitrogen and has carbon-to-nitrogen (C/N) ratios of around 40–70. The optimal C/N ratio for the AD should be between 25 and 35. C/N ratio of sludge in small-scale sewage plants is often low, so nitrogen can be added in an inorganic form (ammonia or in organic form) such as livestock manure, urea, or food wastes. Potential production capacity of a biogas plant with a digestion chamber size of 500 m³ was estimated as 20–36 × 10³ Nm³ biogas production per year.     

The potential of renewable energy technologies for rural development in Lesotho

The potential and utilization of renewable energy technologies (RETs), and energy analysis in Lesotho with emphasis on the contribution of solar energy technologies (SETs) is presented. The heavy reliance of the country on imported fossil fuel coupled with the growing demand for electricity and declining wood fuel supplies call for alternative sources of energy. Taking the average global solar radiation that ranges from 15 to 20 MJ/m² and cognizant of the short falls of other renewable energy sources in Lesotho, this paper focuses on the application of solar energy and associated developmental issues. The paper provides a statistical analysis of the energy demand and identifies areas of further growth for SETs. Various application areas of solar energy and their contribution to development in Lesotho together with future prospects for use of solar energy are also discussed. An analysis of the relative merits of using photovoltaic (PV) devices over other renewable energy sources in Lesotho is presented. It is argued that with proper economic support and utilization of efficient RETs, developing countries like Lesotho can meet their basic energy demands and alleviate the problems of energy shortages.     

Optimal mix of technologies for rural India: The lighting sector

Despite the obvious associated social benefits, lighting energy for rural areas of India has been largely ignored. Very little attention has been given either to improving efficiencies of existing lighting technologies or to developing alternatives. Comparing technologies for lighting which are both rational and practical for those living in developing countries is difficult owing to the problems of quantifying the social value and assigning rankings based on the quality of the lighting service provided. In the paper, an attempt is made to develop a framework for evaluating the relative economics of some of the common lighting technologies, and this is then incorporated into a linear programming framework to obtain the least-cost option for satisfying the lighting energy demand of a village subject to various constraints in the context of rural areas.