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[en] This paper describes the potential applications of renewable energy sources to replace fossil fuel combustion as the prime energy sources in various countries, and discusses problems associated with biomass combustion in boiler power systems. Here, the term biomass includes organic matter produced as a result of photosynthesis as well as municipal, industrial and animal waste material. Brief summaries of the basic concepts involved in the combustion of biomass fuels are presented. Renewable energy sources (RES) supply 14% of the total world energy demand. RES are biomass, hydropower, geothermal, solar, wind and marine energies. The renewables are the primary, domestic and clean or inexhaustible energy resources. The percentage share of biomass was 62.1% of total renewable energy sources in 1995. Experimental results for a large variety of biomass fuels and conditions are presented. Numerical studies are also discussed. Biomass is an attractive renewable fuel in utility boilers. The compositions of biomass among fuel types are variable. Ash composition for the biomass is fundamentally different from ash composition for the coal. Especially inorganic constituents cause to critical problems of toxic emissions, fouling and slagging. Metals in ash, in combination with other fuel elements such as silica and sulfur, and facilitated by the presence of chlorine, are responsible for many undesirable reactions in combustion furnaces and power boilers. Elements including K, Na, S, Cl, P, Ca, Mg, Fe, Si are involved in reactions leading to ash fouling and slagging in biomass combustors. Chlorine in the biomass may affect operation by corrosion. Ash deposits reduce heat transfer and may also result in severe corrosion at high temperatures. Other influences of biomass composition are observed for the rates of combustion and pollutant emissions. Biomass combustion systems are non-polluting and offer significant protection of the environment. The reduction of greenhouse gases pollution is the main advantage of utilizing biomass energy. (Author)
[en] The enactment and implementation of the Federal-PURPA together with the State Agricultural Forestry and Residue Utilization Act (SAFRUA) in the 1980's contributed to the unprecedented development of biomass power plants in California, and resulted in over 800 MW of electric capacity. Most biomass projects signed 30 year power purchase contracts. Generally the first 10 years of the contract provided fixed, escalated, or levelized energy prices based on the early 1980's prevailing utility forecasts of avoided costs. Projects committing to firm capacity received levelized avoided capacity prices ranging from $140-200/kW-year, depending on what year the project became operational. The impending end of the fixed energy price period when biomass projects will receive lower avoided energy costs based on natural gas prices will cause a substantial number of these projects to become uneconomic. It is possible that many of the contracts will be terminated triggering capacity repayment provisions, forcing some projects into bankruptcy. This paper presents the California Energy Commission staff's perspective on the issues affecting the sustainable generation and long term commercial viability of these power plants. A review of the technical, economic, and environmental barriers and potential short-term and long-term solutions to these barriers are also discussed
[en] This paper provides a status report on recent utility efforts to evaluate cost-effective opportunities for developing advanced gasification biomass power generation facilities and, in some cases, to actually begin developing the facilities. An overview is provided of national estimates of the potential for producing electricity from various biomass feedstocks. Major manufacturers of advanced gasification biomass power generation technologies are described. Major biomass power generation projects underway by utilities in the US are described. Significant issues affecting further commercialization of biomass gasification facilities are discussed and strategies for addressing the barriers are suggested
[en] Building of new waste-fueled CHPs has been economically evaluated. Total investment cost have been calculated for plants of three different sizes, 2x15, 2x25, and 2x50 MW thermal power, respectively. The calculations show that the small plants have poor and the large plants mediocre profitability. Better economy can be achieved for the large plants if a higher steam quality than normal is used (120 bar, 540 degree C instead of 40 bar, 400 degree C). The conclusions are that investment subsidies are necessary for building these plants, in particular the small ones. Subsidy levels are estimated according to two principles: Pay-back no later than eight years after commissioning, or covering of deficits until revenues surpasses capital costs. Use of biofuels to level the fluctuations in waste flow, and thus make more efficient use of the plant, can also help the economy of the plant. (8 figs., 15 tabs.)
[en] This thesis explicitly presents the problem of municipal solid waste and the possible methods of its disposal. Concentration is laid upon incineration in all its variations, through the different systems employed or the kind and quality of refuse burned. Three effective world-wide disposal technologies (Landfilling, Composting, Incineration) are discussed fully, taking into consideration the theoretical, economical, environmental, and practical aspects of each technology; on which a complete comparison can be based, leading to a correct selection in accordance with local criteria. Waste-to-energy systems are analyzed in detail, showing the effect of refuse quantity and quality on the performance and efficiency of such plants. Additionally, insight on existing facilities and on future new systems that could be more effective in power generation is provided. In addition to steam-cycle based plants, the exhaust-heated fuel-boosted gas-turbine cycle (EHFBGT) is newly introduced design featuring both flexibility and high efficiency. Hence, if introduced into practice, may surpass other incineration technologies, since it could act as a refuse incinerator and power plant at same time. The solid waste problem in Beirut is discussed in particular, presenting the results of waste analysis performed over a period of 12 months. Statistical data on population and refuse generation together with current disposal methods are presented, leading to recommendations on the most feasible and practical technologies that could be used in solving the solid waste problem. The preferred current alternative is a combination of composting and incineration of Beirut solid waste with roughly equal proportions at existing site locations. Ultimately, the introduction of properly designed (Combined Plants) may obviously offer certain benefits. (author) Refs. Tabs. Figs
[en] The solving of raw material and energy problems has become one of the central tasks of politics world-wide in recent years. Against the background of the earth's limited supply of raw materials, both consumers and producers are urged to contribute to the conservation of resources. The following could contribute towards the reduction of the cumulative expenditure of energy and thereby towards the conservation of raw materials: - a reduction in the use of material by means of material-saving production; - the recovery of recyclable parts; - the recovery of used raw materials in the economic cycle and - finding substitutes for production materials made of scarce raw materials or whose production is energy-intensive. The energy evaluation of a product must be viewed as a whole, taking these viewpoints into consideration, i.e. all processes, including the recovery and recycling of materials. (orig./UA)
[de]Die Loesung von Rohstoff- und Energieproblemen ist in den letzten Jahren weltweit zu einer zentralen Aufgabe der Politik geworden. Vor dem Hintergrund der begrenzten Rohstoffvorraete der Erde sind Verbraucher und Produzenten angehalten, zur Schonung von Ressourcen beizutragen. Zur Senkung des kumullierten Energie-Aufwandes von Produkten und damit zur Einsparung von Rohstoffen koennen beitragen: - ein verringerter Materialeinsatz durch stoffeinsparende Produktion, - die Rueckfuehrung wiederverwendbarer Teile, -die Rueckfuehrung gebrauchter Rohstoffe in den Wirtschaftskreislauf und - die Substitution von Werkstoffen aus seltenen Rohstoffen bzw. mit energieintensiven Produktionsverfahren. Unter diesen Gesichtspunkten muss die energetische Bewertung eines Produkts nach einer ganzheitlichen Betrachtung erfolgen, d.h. es sind alle Prozesse inklusive Materialruecklauf und Wiederverwertung einzubeziehen. (orig./UA)
[en] This paper reports that some regions have prepared for these days of disposal shortage with comprehensive waste plans that include a strong WTE presence. Witness Broward County, Florida's program, 12 years in planning by public and private entities, Broward is the second most populated county in the state, with 1.3 million residents and a heavy tourist population, which, together, produce 1.6 million tons of waste annually. The disposal program includes Waste Management, Inc.'s expansion of a 400-acre Central Disposal Sanitary Landfill, the county's new 588-acre landfill, composting, and curbside pickup for recyclables. And, this south Florida plan would not be complete without the two brand new combustion plants. Clean Air and Water Acts notwithstanding, the Florida Department of Environmental Regulation can induce standards stricter than the federal government's due to the sensitive South Florida ecology. Wheelabrator was prepared for all eventualities with its design which uses state-of-the-art scrubbers, bag houses, and monitoring to track and capture the trace amounts of lead, cadmium, and mercury, which end up in the ash. In fact, tests at other Wheelabrator facilities using similar technology showed that heavy metals in leachate from the residue showed up in concentrations as much as 200 times lower than the EPA criteria for toxicity
[en] This report summarises the results of the emissions monitoring programme undertaken by FEC Consultants at EYE power station. It has shown that poultry litter can generally be burnt in a clean and efficient manner with due regard to the environment. The emissions monitored with the exception of particulates generally conform with the requirements of IPR 1/7 (92); particulates exceed the 100 mg/Nm3 but are within the 200 mg/Nm3 allowed for the first 12 months of operation. The particulate burden from the large scale combustion of poultry litter has exceeded expectations. The environmental monitoring programme undertaken by ADAS Huntingdom, at 'EYE' power station over a period of 16 months, has shown there was no evidence of the deposition of harmful substances from the chimney onto the surrounding plants and soil. To alleviate the fears of the NFU over possible contamination to the food chain from chimney deposition, MAFF, Food Safety (Contaminants) Unit, undertook to collect milk samples over a period of 16 months. These milk samples were subject to analysis for dioxin and furan contamination. The analysis has shown that the dioxin and furan contents were at the bottom of the normal background levels for the UK and there was no evidence of any increase over the sampling period. (author)
[en] This study aims at evaluating whether it is possible to combine together the use of a Refuse Derived Fuel (RDF) plant for energy recovery and a sea water desalination unit in order to produce both electricity and potable water at competitive costs.
[it]L'accoppiamento di un impianto di recupero energetico da frazioni combustibili derivate da rifiuti urbani (CDR) con un impianto di dissalazione di acqua di mare, consente di realizzare una significativa produzione sia di energia elettrica, sia di acqua potabile con costi competitivi.
[en] A theoretical study was performed on the effects of substituting straw for brown coal as a fuel in an existing heating station taking into account the complete process chains. An efficiency of 85% and distribution losses of 5% were assumed for the straw-fired heating station. Emission levels were determined for pollutants and for CO2 for its climatic impact. Furthermore, the influence of other climatically relevant emissions was taken into account and grouped together with that of CO2 under the heading CO2-equivalent emissions. (orig./EF)
[de]Es wurde der Ersatz der bisherigen Braunkohlenfeuerung durch ein Strohheizwerk unter Beruecksichtigung der vollstaendigen Prozessketten betrachtet. Das Strohheizwerk wurde mit 85% Wirkungsgrad und 5% Verteilungsverlusten angesetzt. Neben der Emission von Schadstoffen wurde auch die klimarelevante CO2-Emission ermittelt. Zusaetzlich wurde auch der Einfluss anderer klimarelevanter Emissionen beruecksichtigt und zusammen mit der CO2-Emission unter der Bezeichnung CO2-Aequivalente Emissionen zusammengefasst. (orig./EF)