Hydrogen as a transportation fuel produced from thermal gasification of municipal solid waste: an examination of two integrated technologies

Innovative technologies are required to offset increasing consumption and declining stocks of non-renewable resources. This study examines a possible enhancement of waste management and transportation by integrating two emerging technologies: municipal solid waste (MSW) gasification and fuel cell vehicles (FCVs), by fueling FCVs with hydrogen produced from gasified MSW. Material and energy flows were modeled in four MSW management scenarios (incineration, landfill, gasification, gasification with recycling) and four transportation scenarios (hybrid gasoline-electric, methanol FCVs, hydrogen FCVs using hydrogen from natural gas or municipal solid waste). Technological performance deemed feasible within 2010–2020 was assumed. Greenhouse gas emissions and non-renewable energy use were used to assess overall system performance. Gasification with hydrogen production performs as efficiently as incineration, but is advantageous compared to landfilling. Taking into account additional environmental criteria, the model suggests that hydrogen from MSW gasification for FCVs may provide benefits over conventional MSW treatment and transportation systems.     

我国垃圾填埋场填埋气体排放和回收利用现状分析

城市生活垃圾填埋气体的回收和资源化利用是一项经济可行且对环境有益的技术。本文介绍了我国目前垃圾填埋气体产生、排放及利用情况,分析了几种填埋气体利用技术的特点及其在我国的适用性,并提出了未来我国城市生活垃圾处理的主要方向,即建立配备填埋气体回收装置的卫生填埋场。     

上海市生活垃圾处理问题的系统动力学分析

与日俱增的人口产生了越来越多的生活垃圾.面对垃圾围城的严峻形势,城市生活垃圾处理变得越来越迫切.为了预测上海市未来的垃圾产生量,探讨合适的处置方法和调控措施,利用系统动力学的方法建立了上海市城市生活垃圾产生和处理系统的动力学模型.通过查阅大量文献并收集数据,预测未来生活垃圾的产生总量和处理总量,对各种处理方式的收益进行了对比,并利用系统动力学模型模拟软件VENSIM进行了模拟.结果表明:在调控措施下,未来上海市垃圾产生量能得到控制和更加环保的处理;同时,需要控制人口,提高环保投资占GDP比重,实行垃圾收费制度.     

矿化垃圾一种可再生的燃料矿藏

分析了10年陈矿化垃圾组分特性，讨论了矿化垃圾用作可再生燃料的经济性与潜力及可行性。研究发现矿化垃圾中的可燃成分以塑料为主，另有木竹和纤维。与新鲜垃圾相比水份低，制作燃料（垃圾衍生燃料）无需干燥步骤，过程卫生，无臭气，制成工艺可望更简单。矿化垃圾作为再生燃料利用不仅可以回收能源，而且为城市垃圾的处理提供了经济、长效机制。     

杭州市生活垃圾优化处理技术分析

对杭州市生活垃圾的特性和处理现状进行了分析时比。根据该市生活垃圾处理处置存在的问题，提出生活垃圾资源化综合优化处理技术。该技术综合了填埋、堆肥和焚烧三种处理方法优点，可以实现生活垃圾的减量化、资源化和无害化，具有很好的社会、环境和经济效益。     

Municipal solid waste (MSW)-to-energy in China: challenges and cost analysis

Municipal solid waste (MSW) is one of the most abundant resources that can be used in producing electricity. Considering population growth in countries, changing human lifestyles, and growth of urbanization, the quantity of MSW is continuously increasing and has confronted many countries including China with serious problems. The present research intended to investigate and study challenges that MSW confronts as a reliable fuel for providing global energy needs (including those of China). This article deals with the quantity of MSW produced globally and in China and cost analysis first and then studies ways of extracting energy from MSW with an emphasis on gasification.     

1台350t/d垃圾焚烧立式余热锅炉的设计

随着城市化进程的推进,生活垃圾日益增多,垃圾处理迫在眉睫。深入分析了我国生活垃圾的特性,阐述了垃圾焚烧余热锅炉的工作原理,介绍了350 t/d垃圾焚烧立式余热锅炉的设计参数及结构特点。垃圾焚烧锅炉对生活垃圾的回收利用和环境保护有着积极的意义。     

Energy from municipal solid waste: A comparison with coal combustion technology

The conversion of municipal solid waste (MSW) to energy can conserve more valuable fuels and improve the environment by lessening the amount of waste that must be landfilled and by conserving energy and natural resources. The importance of utilizing MSW was recognized in the 1991 U.S. National Energy Strategy, which sought to “support the conversion of municipal solid waste to energy.” One route to utilizing the energy value of MSW is to burn it in a steam power plant to generate electricity. Coal has long been the predominant source of energy for electricity production in the U.S.; therefore, a considerable science and technology base related to coal combustion and emissions control can be, and has been, applied with substantial benefit to MSW combustion. This paper compares the combustion of coal and MSW in terms of fuel characteristics, combustion technology, emissions, and ash utilization/disposal. Co-combustion of coal and MSW is also discussed. MSW issues that can be addressed by research and development are provided.The major environmental issues that designers of MSW combustion systems have had to address are emissions of trace organic compounds, particularly polychlorinated dioxins and furans, and trace elements such as mercury, lead, and cadmium. Emission of trace organics is generally the result of a poorly designed and/or operated combustion system; modern MSW systems use good combustion practices that destroy organic compounds during the combustion process. Proper control of air/fuel mixing and temperature, and avoidance of “quench” zones in the furnace, help to ensure that potentially harmful organics are not emitted. Computer codes and other design and troubleshooting tools that were developed for coal combustion systems have been applied to improve the performance of waste-to-energy systems.Trace element emissions from both coal and MSW combustion result primarily from vaporization of elements during the combustion process. Most of the trace elements that are vaporized condense on fly ash as the combustion products cool downstream of the furnace and can be effectively controlled by using an efficient particulate removal device. However, volatile elements, particularly mercury, are emitted as a vapor. Several mechanisms are available to capture mercury vapor and some are in use. The development of satisfactory control technology for mercury is a topic currently of high interest in coal burning.The potential for leaching of trace elements and organics from MSW residues after disposal raises issues about the classification and management of ash. Results of laboratory leaching tests, especially for lead and cadmium, have not been consistently supported by field experience. Careful interpretation of the available test protocols is needed to make sure that residues are properly managed.Because of the large scale of coal-fired boilers for electricity production, co-firing of MSW with coal in such boilers could consume large quantities of waste. Several short-term demonstrations have shown that co-firing is feasible. The issues involved in co-firing are emissions of trace elements, trace organics, and acid gases; boiler slagging and fouling; and long-term effects, such as corrosion and erosion of boiler tubes.Areas where research and development has contributed to improved MSW combustion include (a) the formation mechanisms of polychlorinated dioxins/furans, especially low-temperature, catalytic mechanisms, (b) methods of combustion air distribution in incinerators that result in better combustion and reduced emission of organic compounds, (c) the use of gas reburning to control NOx and reduce emission of organic compounds, (d) practical methods for removing organic compounds and mercury from MSW flue gas, (e) the performance of electrostatic precipitators in removing MSW fly ash, particularly when co-firing MSW and coal in existing coal-fired boilers, and (f) burning MSW in fluidized beds or of pulverizing refuse-derived fuel and firing it in suspension-fired, pulverized coal boilers.     

金华城市生活垃圾焚烧发电可行性研究

通过对金华市区垃圾产量和处理现状调研表明,金华市城区城市生活垃圾的日产量在450t／d以上．并以15％的年增长速度增长。随着城市化进程的加快,原有的垃圾填埋场即将饱和,而新的垃圾填埋场选址困难,垃圾焚烧处理是一条比较可行的无害化、资源化的减客手段。以煤作为辅助燃料,提高入炉垃圾的热值,进行清洁焚烧发电是可行的。因此,采用流化床焚烧发电技术,结合浙江八达金华热电有限公司的原有设备和人员,垃圾焚烧后发电供热,实现变废为宝、资源综合利用的目标。     

Carbon footprint assessment for the waste management sector: A comparative analysis of China and Japan

Waste management is becoming a crucial issue in modern society owing to rapid urbanization and the increasing generation of municipal solid waste (MSW). This paper evaluates the carbon footprint of the waste management sector to identify direct and indirect carbon emissions, waste recycling carbon emission using a hybrid life cycle assessment and input-output analysis. China and Japan was selected as case study areas to highlight the effects of different industries on waste management. The results show that the life cycle carbon footprints for waste treatment are 59.01 million tons in China and 7.01 million tons in Japan. The gap between these footprints is caused by the different waste management systems and treatment processes used in the two countries. For indirect carbon footprints, China’s material carbon footprint and depreciation carbon footprint are much higher than those of Japan, whereas the purchased electricity and heat carbon footprint in China is half that of Japan. China and Japan have similar direct energy consumption carbon footprints. However, CO₂ emissions from MSW treatment processes in China (46.46 million tons) is significantly higher than that in Japan (2.72 million tons). The corresponding effects of waste recycling on CO₂ emission reductions are considerable, up to 181.37 million tons for China and 96.76 million tons for Japan. Besides, measures were further proposed for optimizing waste management systems in the two countries. In addition, it is argued that the advanced experience that developed countries have in waste management issues can provide scientific support for waste treatment in developing countries such as China.     

城市垃圾焚烧产物对环境的影响及其资源化利用

阐述了城市垃圾焚烧飞灰的基本性质和不同粒径颗粒所含各种重金属含量以及它们对水体和环境的危害,介绍了不同粒径飞灰的物理化学性质和在不同条件下的处理方式,在此基础上提出了一种"无害化"、"资源化"、"减量化"的有效措施处理飞灰,即水泥窑煅烧处理;还介绍了城市垃圾焚烧产物中二噁英的基本性质、毒性和对人体的危害,从垃圾入炉前、焚烧时、烟气中等三个方面进行处理,并提出了减少二噁英的生成防治措施及去除的方法;介绍了城市垃圾焚烧底灰的物理化学性质,提出了一种资源化利用的方案,即制成烧结砖.     

城市生活垃圾焚烧飞灰中重金属污染与控制

针对城市生活垃圾焚烧飞灰中的重金属污染问题,介绍了焚烧飞灰中重金属生成机理及来源,并重点阐述了国内外对焚烧飞灰中重金属的稳定化处理方法及控制措施,为垃圾焚烧飞灰的无害化、资源化处理提供了必要的理论参考,并提出了未来垃圾焚烧飞灰中重金属污染物处理的发展方向.     

上海城市生活垃圾循环利用分析研究

对上海城市生活垃圾清运量、组分、收集模式和处理处置的现状及其存在的问题进行了调查分析.并在此基础上，从源控制减量措施、分类清运模式、处理系统和树立循环经济管理理念等四个方面，分析研究了上海城市生活垃圾的循环利用，为今后进一步研究适合于上海的安全、科学和有效的多元化垃圾处理体系打下了基础。     

Thermodynamic equilibrium model and second law analysis of a downdraft waste gasifier

The management of municipal solid waste (MSW) and the current status of world energy resources crisis are important problems. Gasification is a kind of waste-to- energy conversion scheme that offers the most attractive solution to both waste disposal and energy problems. In this study, the thermodynamic equilibrium model based on equilibrium constant for predicting the composition of producer gas in a downdraft waste gasifier was developed. To enhance the performance of the model, further modification was made by multiplying the equilibrium constants with coefficients. The modified model was validated with the data reported by different researchers. MSW in Thailand was then used to simulate and to study the effects of moisture content (MC) of the waste on the gasifier's performance. The results showed that the mole fraction of H₂ gradually increases; CO decreases; CH₄, which has a very low percentage in the producer gas increases; N₂ slightly decreases; and CO₂ increases with increasing MC. The reaction temperature, the calorific value, and the second law efficiency, decrease when MC increases.     

Life cycle assessment of fuels for district heating: A comparison of waste incineration,biomass- and natural gas combustion

The aim of this consequential life cycle assessment (LCA) is to compare district heating based on waste incineration with combustion of biomass or natural gas. The study comprises two options for energy recovery (combined heat and power (CHP) or heat only), two alternatives for external, marginal electricity generation (fossil lean or intense), and two alternatives for the alternative waste management (landfill disposal or material recovery). A secondary objective was to test a combination of dynamic energy system modelling and LCA by combining the concept of complex marginal electricity production in a static, environmental systems analysis. Furthermore, we wanted to increase the methodological knowledge about how waste can be environmentally compared to other fuels in district-heat production. The results indicate that combustion of biofuel in a CHP is environmentally favourable and robust with respect to the avoided type of electricity and waste management. Waste incineration is often (but not always) the preferable choice when incineration substitutes landfill disposal of waste. It is however, never the best choice (and often the worst) when incineration substitutes recycling. A natural gas fired CHP is an alternative of interest if marginal electricity has a high fossil content. However, if the marginal electricity is mainly based on non-fossil sources, natural gas is in general worse than biofuels.     

促进城市生活垃圾场填埋气体资源化的有关问题

本文从技术示范、管理体制、政策法规等几个方面阐述并分析了我国当前在鼓励城市生活垃圾填埋气体资源化利用方面存在的亟待解决的问题和障碍,并提出了针对这些问题的政策建议。     

Pyrolytic liquid fuel: A source of renewable electricity generation in Makkah

Millions of Muslims from all over the world visit the Holy Cities of Saudi Arabia: Makkah and Madinah every year to worship in form of Pilgrimage (Hajj) and Umrah. The rapid growth in local population, urbanization, and living standards in Makkah city along with continually increasing number of visitors result in huge municipal solid waste generation every year. Most of this waste is disposed to landfills or dumpsites without material or energy recovery, thus posing substantial environmental and health risks. The municipal plastic waste is the second largest waste stream (up to 23% of total municipal waste) that is comprised of plastic bottles, water cups, food plates, and shopping bags. The sustainable disposal of plastic waste is challenging task due to its clogging effects, very slow biodegradation rates, and presence of toxic additives and dyes. Pyrolysis is one of the promising waste-to-energy technology for converting municipal plastic waste into energy (liquid fuel) and value-added products like char. The produced liquid fuel has the potential to be used in several energy-related applications such as electricity generation, transportation fuel, and heating purposes. It has been estimated that the plastic waste in Makkah city in 2016 can produce around 87.91 MW of electricity. This is projected to increase up to around 172.80 MW of electricity by 2040. A global warming potential of 199.7 thousand Mt.CO₂ eq. will be achieved with savings of 7.9 thousand tons emission of CH₄, if pyrolysis technology is developed in Makkah city. Furthermore, a total savings of 297.52 million SAR from landfill diversion, electricity generation, and carbon credits would be possible to achieve in 2016 from pyrolysis. These economic benefits will increase every year and will reach up to 584.83 million SAR in 2040.     

能量自给型垃圾堆肥系统优化与污染物排放控制

根据城市生活垃圾的特性,进行垃圾综合处理,充分利用垃圾中各组分的有用价值。对能量自给型垃圾堆肥综合系统选择与整合集成进行详细的分析,同时测定和分析了运行过程中的污染物排放及生产产品肥料的质量。从环境污染控制和垃圾物尽其用的角度,对系统进行优化与选择集成的分析,提出对垃圾系统工程进行改善的建议,污染物的控制措施急待加强。     

RDF production plants: I Design and costs

Municipal solid waste (MSW) management calls for the integration of different recovery, recycling and disposal technologies. Among these possible options, MSW may be treated in order to obtain a fuel to be sold to third party users or directly utilized to generate electricity provided it is of sufficient quality to be employed instead of traditional fuels. In this two-part paper the problem of producing refuse derived fuel (RDF) having a high heating value (LHV>4000 kcal/kg) has been examined from a technical and economic viewpoint. In the first part article a technical assessment of production plants is carried out. Different production lines have been thus compared in terms of mass efficiency, heating value of produced RDF and treatment cost highlighting how the choice of process equipment affects the system performances. As a result the process plant configurations enabling to meet the required product specifications are identified. The influence of mixing a high calorific waste such as scrap tires with the stream of household waste, in the limits allowed by current regulation, has been also analyzed and found to be a prerequisite to meet the prescribed heating value target. Economic feasibility and financial risk of RDF production plants have been successively evaluated in the second part article over a capacity range of 25–200 t/h considering also integrated facilities including compost production and/or electricity generation. The analysis has been carried out with reference to the current Italian market scenario even if it has a general applicability and its relevance is wider geographically.     

From biogas-to hydrogen – Based integrated urban water,energy and waste solids system - Quest towards decarbonization

Three integrated systems of water and municipal solid waste (MSW) management were evaluated regarding their energy use, production and CO_2eq emissions:(1) Biogas based aerobic treatment of wastewater and waste solids disposal by landfilling wherein codigesting sludge with MSW and landfill gas capture produce electricity by a turbine and generator.(2) Biogas based wastewater treatment with codigestion of sludge with biodegradable solids combined with incineration of combustible sludge and other solids.(3) Hydrogen-based system replacing landfilling by indirect gasification of organic solids followed by hydrogen fuel cells.There are great differences between CO_2eq emissions of biogas and hydrogen-based systems. The first two systems are positive CO₂ and methane emitters. Achieving net zero carbon emissions is unlikely. The H₂ based system is fully decarbonized and in addition to clean water, energy and negative carbon dioxide emissions it produces valuable commodities such as energy, concentrated hydrogen, fertilizers, oxygen/ozone, and concentrated carbon dioxide.