Agricultural waste resources and biogas energy potential in rural areas of Lao PDR

Lao PDR lacks of conventional energy resources, such as oil and natural gas, and 100% of fossil fuels are imported from abroad. Fossil fuel consumption in Lao PDR in 2010 was about 561 million liters and rapidly increased to 716 million liters by 2015. However, Lao PDR has a high potential for renewable energy, especially from hydropower, agricultural wastes, and livestock wastes, in which agricultural and livestock annually produced a large amount of agricultural residues as a favorable renewable energy sources. In 2016, productivity crops were estimated for 24,608,840 ton and these products amount can be generated annual agricultural residues for 12,525,000 ton, which can be estimated to total of energy potential was 197,840 GJ or 55,001 GWh. The majority of livestock in country are buffaloes, cattle, swine, and poultry; large amount of livestock manure produced from each region and can be feedstock as substrate for biogas digester, which these amounts were estimated about 1,583,740 kg TS/day, and equivalent to 439,917 m3/day of biogas production or 658,376 kWh/day of energy generation. Therefore, objective of this paper is unique to promote and research development the agroforestry residues and livestock wastes as renewable energy resources, and its energy potential for biofuel production, including, biodiesel, bioethanol and biogas in each region of Laos.     

Performance analysis of energy recovery in an Italian municipal solid waste landfill

The objective of this paper is to assess the techno-economic viability of the use of fuel cell as an alternative technology for landfill gas energy recovery. The case of an Italian municipal solid waste landfill is analyzed. The landfill was opened in 1998 and in 2001 the energy recovery facility started operation. The current landfill gas conversion system is based on internal combustion engine technology. However, the drawbacks of internal combustion engine in terms of conversion efficiency and air emissions are widely acknowledged. Some authors have proposed molten carbonate fuel cell as one of the most interesting solution for landfill gas energy recovery for the near future. Fuel cells have proven capable of providing superior energy efficiency and environmental performance, but their widespread use is constrained by the capital cost required. Using actual data from the landfill, a comparison between the current energy recovery system and a hypothetical alternative solution based on molten carbonate fuel cell is performed. The analysis assesses the cost-effectiveness of the two solutions, considering also some environmental externalities usually not included in traditional economic assessment. The main strengths and weaknesses of the two landfill gas energy recovery systems are highlighted and some new insights into molten carbonate fuel cell overall sustainability are provided.     

北京市餐厨垃圾产生状况及厌氧发酵产气潜力分析

随着餐饮行业的发展,越来越多的餐厨垃圾造成的污染成为我们亟待解决的问题.文章通过对北京市城区的餐馆进行实地调查,针对不同规模的餐馆,分别对其餐厨垃圾产生的数量、成分、性质及其收集处理方式、处理费用和最终用途进行了深入的调查分析;并对中国目前的管理政策进行了探讨.文章还通过批式厌氧消化实验对学校食堂的餐厨垃圾进行了产气潜力分析,结果显示在20g/L的容积污染负荷下,经过35 d的中温(35℃)消化,总产气量达到7 380 mL,总甲烷量达到4 023 mL,甲烷含量平均为54.51%,VS去除率为50%,产气率和产甲烷率分别达到369ml/g和201 ml/g,实验表明餐厨垃圾具有很好的产气性能,为进一步研究提供了理论基础.     

Specific applications of bio/landfill gas produced from waste organic material

This paper describes three electricity and/or heat generation applications fuelled by biogas or landfill gas produced from organic waste material. It shows that aerobic and/or anaerobic treatment of the waste has many environmental and economical benefits especially now that pollution is a major international problem, and that energy cost is escalating not only because of the increased energy demands but also the realisation that the fossil-fuel-based sources of energy are limited and “unfriendly” to the environment. It is noted that cogeneration is currently the most suitable energy management strategy for applications requiring both heat and power simultaneously.     

木耳种植废料的低焦油气炭联产技术研究

文章利用生物质复合式固定床低焦油热解气化中试装置,对木耳种植废料进行了热解气化、产炭试验研究,探讨了以木耳种植废料为原料的复合式固定床低焦油气化炉的启动特性,二次风量对气体重整区温度和出炉燃气热值的影响,气体重整区温度对燃气成分和焦油裂解的影响,出炭量对生物质炭品质的影响以及稳定工况下的炉内温度分布等。试验结果表明:复合式固定床气化装置启动时间较长;二次风量与气体重整区的温度呈正向变化,与燃气热值呈反向变化;气体重整区的高温对燃气中焦油的裂解效果显著;气炭联产适宜的出炭率为25%~30%。文章研究结果对木耳种植废料的能源化利用具有指导意义。     

Status and potential of biogas energy from animal wastes in Turkey

Biogas is a potentially important energy source that can be used for the production of heat, electricity and fuel. It can be produced at wastewater treatment plants, landfills, food and other industrial operations throughout the world. There is largely untapped potential in agricultural operations where animal waste is often land applied or otherwise disposal of without conversion to energy. According to the last agricultural census (2009) in Turkey; there are a total of 3,076,650 agricultural enterprises and approximately 70% of these enterprises are running livestock farming. 10,811,165 of total animal is cattle, 26,877,793 of total animal is small ruminant and 234,082,206 is poultry. The amount of wet waste of these animals is about 120,887,280 t. These wastes could be a major problem for enterprises and cannot be utilized properly. The best way to utilize waste is to produce biogas. In this study, biogas amount which will be obtained from animal waste was calculated for all provinces by using the number of livestock animals and also considering various criteria such as the rate of dry matter and availability. Animal origin waste map of Turkey was also produced with these calculated values. The biogas energy potential of Turkey was found to be 2,177,553,000 m³ (2.18 Gm³) by using the animal numbers in the last agricultural census (2009). The total biogas potential is originated from 68% cattle, 5% small ruminant and 27% poultry. Biogas energy equivalence of Turkey is approximately 49 PJ (1170.4 ktoe). When the prepared waste map is examined; provinces that have more than 1 GJ of biogas energy potential are found to be; Bolu, Bal?kesir, ?zmir, Sakarya, Konya, Manisa, Erzurum, Afyon, Kars and Ankara respectively.     

Estimate of the electric energy generating potential for different sources of biogas in Brazil

The increasing interest in the recuperation of the biogas coming from organic residues, associated with its energetic use is a subject that has been widely discussed. Biogas was merely seen as a sub-product obtained from anaerobic decomposition (without oxygen) of organic residue. In the paper is carried out an evaluation of the quantities of organic residues coming out from the sugar and alcohol industry (vinasse), urban solid and liquid wastes (garbage and sewage) and livestock residues (bovine and swine manure) in Brazil. Finally the electricity generation potential of biogas out of the evaluated sources of organic residues in Brazil is estimated. The results of this study indicate that the potential regarding the production of biogas out of the aforementioned organic residues of electricity production using could meet an energy demand of about 1.05 to 1.13 %. Constraints for biogas energy utilization are identified and discussed.     

Wave energy potential in Galicia (NW Spain)

Wave power presents significant advantages with regard to other CO₂-free energy sources, among which the predictability, high load factor and low visual and environmental impact stand out. Galicia, facing the Atlantic on the north-western corner of the Iberian Peninsula, is subjected to a very harsh wave climate; in this work its potential for energy production is assessed based on three-hourly data from a third generation ocean wave model (WAM) covering the period 1996–2005. Taking into account the results of this assessment along with other relevant considerations such as the location of ports, navigation routes, and fishing and aquaculture zones, an area is selected for wave energy exploitation. The transformation of the offshore wave field as it propagates into this area is computed by means of a nearshore wave model (SWAN) in order to select the optimum locations for a wave farm. Two zones emerge as those with the highest potential for wave energy exploitation. The large modifications in the available wave power resulting from relatively small changes of position are made apparent in the process.     

Wave energy potential along the Death Coast (Spain)

The newly available SIMAR-44 data set, covering a 44-year period, is used together with wave buoy data to assess the wave energy resource along the Death Coast, the craggy stretch from Cape Finisterre to the Sisarga Isles. Its location at the north-western corner of the Iberian Peninsula and its coastline configuration result in exposure to a wide range of wave directions over the long Atlantic fetch. A total of 18 study sites are analysed—16 SIMAR-44 points and two wave buoys. Annual wave power in the Death Coast area is of the order of 50 kWm⁻¹, and annual wave energy exceeds 400 MWhm⁻¹. This vast resource is characterised thoroughly in terms of wave directions, heights and periods. A coastal wave propagation model (SWAN) is then implemented, validated based on wave buoy measurements, and used to investigate the nearshore energetic patterns. The irregular bathymetry of the Death Coast is shown to lead to local concentrations of wave energy off Capes Veo, Tosto and Finisterre and north of the Sisargas Isles, which are more conspicuous in winter and, especially, in storm situations.     

Development of an investment decision tool for biogas production from agricultural waste

Anaerobic digestion is a very promising solution for the treatment of agricultural waste, preventing pollution and leading to efficient energy production. Since this technology is available to each farmer in a different way depending on the location and the scattering of the primary sources, it is essential to clarify the best conditions adapted to local situations to treat the targeted residues and make this information accessible to farmers. In particular the possibility of codigestion seems to be very attractive for farmers who will be able to treat their own waste together with other organic substrates. Their profit in this case is double since they treat properly their own residues, taking advantage of the selling of heat and electricity as well as the utilisation of a stabilised biofertiliser. The aim of this paper is to present an investment decision kit for economic evaluation of biogas plant projects based on agricultural feedstocks.     

The technical potential of first-generation biofuels obtained from energy crops in Spain

Biofuels have been recently the subject of a sustained interest due to the ambitious goals set out in developed, and some developing, countries as they transition to more sustainable and self-sufficient energy models. Thus, EU Directive 2003/30 established certain minimimun shares of biofuels in the transport sector for the member states, viz 2% by 2005 and 5.75% by 2010. More recently, the EU Directive 2009/28/EC imposes a target share of 10% renewables in the transport sector by 2020. Different roadmaps can be envisaged based on the varying contributions from first and second-generation biofuels; the controversial role of biomass imports for biofuel production adds some additional uncertainties. Against this backdrop, this work presents a comprehensive view of the technical potential for first-generation biofuels (biodiesel and bioethanol) from energy crops in Spain, and their prospects in the short and mid terms. The methodology has been implemented in a Geographical Information System. The calculated technical potentials for biodiesel range between 730 and 1830 ktoe year⁻¹ for land occupations of 10% and 25% of the arable land, respectively. The corresponding bioethanol potentials for the same levels of land occupation are 1228 and 3070 ktoe year⁻¹. The calculated potentials indicate that the Spanish agricultural system would be severely strained if the 2020 target, 4755 ktoe year⁻¹, is to be met with locally-grown biofuel crops. The study further estimates the resulting first-generation biofuel costs, and concludes that incentives are needed for the price to be competitive with that of oil-based fuels, even in a scenario of high oil prices.     

Roof-top solar energy potential under performance-based building energy codes: The case of Spain

The quantification at regional level of the amount of energy (for thermal uses and for electricity) that can be generated by using solar systems in buildings is hindered by the availability of data for roof area estimation. In this note, we build on an existing geo-referenced method for determining available roof area for solar facilities in Spain to produce a quantitative picture of the likely limits of roof-top solar energy. The installation of solar hot water systems (SHWS) and photovoltaic systems (PV) is considered. After satisfying up to 70% (if possible) of the service hot water demand in every municipality, PV systems are installed in the remaining roof area. Results show that, applying this performance-based criterion, SHWS would contribute up to 1662 ktoe/y of primary energy (or 68.5% of the total thermal-energy demand for service hot water), while PV systems would provide 10 T W h/y of electricity (or 4.0% of the total electricity demand).     

High resolution modelling of the on‐shore technical wind energy potential in Spain

The potential of on‐shore wind energy in Spain is assessed using a methodology based on a detailed characterization of the wind resource. To obtain such a characterization, high‐resolution simulations of the weather in Spain during 1 year are performed, and the wind statistics thus gathered are used to estimate the electricity‐generation potential. The study reports also the evolution with the installed power of the capacity factor, a parameter closely related to the cost of the generated energy, as well as the occupied land, which bears environmental and social acceptance implications. A parametric study is performed to assess the uncertainties in the study associated to the choice of the characteristic wind‐turbine farm used; and comparisons are provided with other similar studies. The study indicates that the overall technical potential is approximately 1100 TWh/y; and that about 70 GW of installed wind power could operate with capacity factors in excess of 24%, resulting in an annual electricity generation of approximately 190 TWh/y, or 60% of the electricity consumption in 2008. Copyright © 2010 John Wiley & Sons, Ltd.     

Assessment of energy performance in the life-cycle of biogas production

Energy balances are analysed from a life-cycle perspective for biogas systems based on 8 different raw materials. The analysis is based on published data and relates to Swedish conditions. The results show that the energy input into biogas systems (i.e. large-scale biogas plants) overall corresponds to 20–40% (on average approximately 30%) of the energy content in the biogas produced. The net energy output turns negative when transport distances exceed approximately 200 km (manure), or up to 700 km (slaughterhouse waste). Large variations exist in energy efficiency among the biogas systems studied. These variations depend both on the properties of the raw materials studied and on the system design and allocation methods chosen. The net energy output from biogas systems based on raw materials that have high water content and low biogas yield (e.g. manure) is relatively low. When energy-demanding handling of the raw materials is required, the energy input increases significantly. For instance, in a ley crop-based biogas system, the ley cropping alone corresponds to approximately 40% of the energy input. Overall, operation of the biogas plant is the most energy-demanding process, corresponding to 40–80% of the energy input into the systems. Thus, the results are substantially affected by the assumptions made about the allocation of a plant's entire energy demand among raw materials, e.g. regarding biogas yield or need of additional water for dilution.     

Experimental investigation on the production of biogas from waste food

The production of biogas has been a substantial target to be utilized globally, especially in the agricultural sector. Most organic waste that is being produced from other forms of renewable energy systems is mainly used to reduce greenhouse emission (GHG), which as well reduces the daily consumption of fossil fuels. Anaerobic Digestion (AD) has been studied widely in recent years where its implementation in the industry has seen a mitigating impact on greenhouse gases. Unrestricted discharge of the big amount of waste food (WF) has become the main effect of severe environmental pollution worldwide. Among the various treatment methods, anaerobic digestion (AD) of waste food allows its valorization and the biogas produced can be used as biofuel enhancing the gas supply. In this study, a mechanical pre-treatment with Hollander beater has been applied to break down the particle size of waste food in the way to increase feedstock specific surface areas in other to enhance biogas production. Following, the pre-treatment of waste food during 30 min beating time, the biogas yield achieved a value of about 610.33 ml/gTS. Accordingly, a response surface methodology (RSM) can be used to critically evaluate the effects of process parameter (beating time and temperature) to the output response (biogas production). Pre-treated waste food by Hollander beater at beating time of 30 min enhances biogas production by 80%. An optimum biogas yield was achieved with pre-treatment of waste food at a beating time of 30 min.     

广东省沼气资源潜力与养殖场沼气工程效益分析

文章介绍了广东省养殖场的沼气工艺流程,并利用广东省2017年统计年鉴的数据,评估计算了生猪、奶牛、肉牛、羊和鸡的粪尿量及其潜在的沼气资源量.评估结果表明:2016年广东省沼气资源量为24.37亿m3,若按沼气中含有50％的甲烷气体计,则折合甲烷12.19亿m3,约占广东省同年天然气消费量的7.3％.文章以广州市花都区大...     

Emission reductions potential for energy from municipal solid waste incineration in Chongqing

Municipal solid waste (MSW) is a potential energy resource which can be incineration to energy. Furthermore, it can conserve more valuable fossil fuel and improve the environment by lessening Greenhouse Gas (GHG) emission and the amount of waste that must be landfilled. This paper highlights the MSW generation and characteristics for the city of Chongqing, the nation's fourth largest municipality after Beijing, Shanghai and Tianjin. At present the daily amount of MSW generated per person is about 0.85 kg; food waste accounts for about 53.7% of total MSW. MSW in Chongqing has higher moisture content and lower net caloric value, which is an obstruction for incineration. This paper examines the emission reductions potential for MSW incineration power plant in urban Chongqing. As a case study, emission reductions analysis and economic assessment was implemented for Tongxing MSW incineration power plant. The results show that with the power displacement potential at 235 060 MWh, Chongqing is expected to generate emission reductions as much as 815 862–827 969 tCO₂ and net profit US$7.72 million per annum.     

葡萄籽提油前后发酵产沼气潜力研究

在恒温25℃条件下,采取批量发酵工艺,研究了葡萄籽提油前后产沼气潜力。结果表明:葡萄籽TS,VS发酵产沼气的潜力分别为473.65 mL/g和484.55 mL/g,能源转换效率为37.25%;葡萄籽油枯TS,VS发酵产沼气的潜力分别为450.03 mL/g和460.44 mL/g,能源转换效率为36.43%。     

渗滤液流失造成的MSW填埋气潜能减量

中国城市生活垃圾(MSW)中易生物降解的有机质能产生大量可造成有机污染的渗滤液,这些渗滤液的流失对填埋垃圾的产气能力会产生不利影响,为了确定损失的这部分渗滤液的产气能力,对模拟填埋100 d的处于酸化阶段的渗滤液实施了70d的厌氧消化试验.试验过程中对渗滤液的产气量、甲烷含量、产沼气潜能、pH变化规律及COD去除率做了监测研究.结果表明,渗滤液沼气累积产量为34.55 ml/ml,甲烷浓度为65.0%,渗滤液产甲烷潜能为22.46 ml/g;pH值在开始两天下降至6.7,并在产气阶段逐渐上升到8.3;渗滤液的COD去除率为83.8%.基于对模拟填埋渗滤液的沼气潜能研究,一个开始填埋100d后的中国MSW填埋场流失的填埋气潜能已达到11.5%.