Techno-economic assessment of providing control energy reserves with a biogas plant

Grid stability is being challenged by the increasing integration of power plants with volatile power generation into the energy system. Power supply fluctuations must be compensated by energy system flexibility. The storability of the energy carrier enables biogas plants to generate power flexibly. In this study, the technical and economic effects of providing positive secondary control energy reserves with an Austrian biogas plant were assessed. The plant’s main focus lies in biomethane production with the option of heat and power generation through combined heat and power (CHP) units. A detailed simulation model of the investigated biogas plant was developed, which is presented in this work. Ex-post simulations of one year of flexible plant operation were conducted with this model. The findings show that the installed biogas storage capacity is sufficient to provide control energy reserves while simultaneously producing biomethane. Profitability of providing control energy reserves largely depends on the prices at the control energy market and on CHP unit start-up costs. A cost efficiency analysis demonstrated that investing in a hot water tank with a volume of 5 m³ for short-term heat storage turned out to be economically viable.

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煤体微生物厌氧发酵对裂隙发育的响应规律

基于二维承载条件的煤岩变形过程中的裂隙空间空气渗流试验、梯度含氧水平的煤体微生物厌氧发酵影响试验、与不同煤体粒径的微生物发酵试验,测试了煤体比表面积、裂隙含氧量对煤体厌氧发酵的影响关系,推演了不同深度煤体裂隙发育对厌氧微生物的生物活性影响规律与关键控制因素。结果表明:空气渗流大于1%的煤体中,空气渗流导致的厌氧环境的破坏作用,是抑制煤体厌氧发酵的主控制因素,而且煤体裂隙发育越迅速,空气渗流作用越强,煤体厌氧发酵抑制受控范围越大;空气渗流小于1%的煤体中,在兼氧菌对少量渗流空气缓冲作用影响下,裂隙发育对煤体比表面积的扩大作用是促进煤体厌氧发酵的主控因素,裂隙发育越充分,煤体比表面积越大,煤体的厌氧发酵速率提升越高。     

巨菌草沼渣制备液化多元醇及合成聚氨酯的研究

以巨菌草经厌氧沼气发酵后产生的沼渣为原料,在聚乙二醇(PEG400)和丙三醇的混合溶剂中进行液化制备液化多元醇。研究了液化条件对液化效果的影响。结果表明:巨菌草沼渣最佳液化条件为液化试剂PEG400/丙三醇(质量比)1.5:1、液化温度160℃、液化时间1.5h、液固比(质量比)2.9:1、催化剂浓硫酸用量为液化试剂质量5%。在此条件下,沼渣液化效果最好,制得的液化多元醇羟值为498mg/g,适用于聚氨酯硬质泡沫的生产。用液化多元醇部分代替聚醚多元醇制备聚氨酯材料,质量比为1:1时,所得材料性能最佳,密度和压缩强度分别为38.7kg/m³和0.21MPa。     

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.     

低碳经济背景下我国城市沼气产业化发展前景探析

随着我国城市快速扩张,能源和环境的双重威胁迫使低碳经济成为我国城市未来发展的大趋势,在城市中发展沼气产业对低碳经济的发展具有现实意义。本文针对当前我国沼气发展现状,从社会、经济和环境等角度分析了城市沼气发展的必要性和急迫性。其次,借鉴国外城市沼气的先进技术和实践经验,从技术、原料、产业化三个方面论证城市推广沼气的可行性。最后,探讨了城市沼气应用的多样化发展,为我国低碳经济和低碳城市建设提供了一条新的思路。     

大中型沼气工程生命周期能效评价

基于生命周期评价理论,对山东某沼气工程进行了能效评价。研究得出,该沼气工程生命周期总能耗(折合标准煤)为561 471.47 kg/a(11.54 kg/GJ),其中,化石能耗占96.62%;节能量为1 100 271.42 kg/a;生命周期综合能源利用率为61.82%;生命周期新水耗量为26 552.56 m3/a。利用Sima Pro 8.0.2软件,采用生态指数法分析得出,该沼气工程生命周期产生的环境影响为364.303 3 k Pt/a(7.480 5 Pt/GJ);通过情景分析得出,沼气工程的环境损害减弱能力为191.805 2 k Pt/a(34.49%)。针对该沼气工程存在的一些问题,提出了开发沼液综合利用技术等建议,为提高沼气工程能效、减少环境损害提供理论参考。     

基于生物质气的固体氧化物燃料电池-燃气轮机混合动力系统的性能分析

以生物质气为燃料,建立了固体氧化物燃料电池-燃气轮机混合动力系统的仿真模型.利用所建立的模型进行仿真,根据燃料电池特性参数和压气机、透平特性曲线,分析了燃料质量流量、空气质量流量等参数对混合动力系统性能的影响.结果表明:基于生物质气的固体氧化物燃料电池-燃气轮机混合动力系统的发电效率最高可达61.55%,但在这种情况下系统的寿命和可靠性急剧下降;在设计点工况下,系统的发电效率可达55.31%.燃料质量流量不变,空气质量流量可以在0.084 0~0.179 9kg/s内调节,系统效率变化范围为61.55%~51.43%;空气质量流量不变,为防止压气机发生喘振,燃料质量流量变化范围为0.062 3~0.084 6kg/s,功率变化范围为124.9~187.3kW.     

沼气发动机油的应用

由于沼气的腐蚀性强,润滑性差,沼气发动机需要专用的发动机油润滑.实际使用结果表明,研制的沼气发动机油能够满足W12V190ZD沼气发动机500h换油周期的要求.     

开发产业沼气实现生物天然气对天然气的替代——有机废弃物厌氧处理从“环保主导”向“能源-环保双赢”的转型

论述了我国沼气技术和工程升级换代的必要性和可行路线,沼气资源在中国的多样性,分析了若干探索性的案例。研究发现全国生物天然气生产潜力超过1 000亿m3/a,将成为我国部分地替代供应日趋紧缺的天然气的重要途径。     

柴达木盆地三湖地区第四系生物气藏地震响应特征及应用

柴达木盆地三湖地区第四系由于沉积时间短、成岩作用弱,形成了特有的"低频、低速、同相轴下拉"的地震异常反射特征。通过"时间域"和"深度域"两方面对柴达木盆地三湖地区第四系的地震资料进行解释,得出其第四系的地层分布和构造形态,并发现解释成果与钻探效果高度吻合,据此推测三湖坳陷北斜坡仍然是今后生物气勘探的重要前景区。