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2002 | Buch

New and Renewable Technologies for Sustainable Development

herausgegeben von: Naim Hamdia Afgan, Maria da Graça Carvalho

Verlag: Springer US

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SUCHEN

Über dieses Buch

Sustainable development encompasses economic, social, and ecological perspectives of conservation and change in natural resources. It is generally defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs. This definition is based on the ethical imperative of equity within and between generations. Moreover, apart from meeting; "the basic needs of all"; sustainable development implies sustaining the natural life­ support systems on Earth, and extending to all the opportunity to satisfy their aspirations for a better life. Hence, sustainable development is more precisely defined as a process of change in which the exploitation of resources, the direction of investments, the orientation of technological development, and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspiration. To date, various definitions and stationary-state criteria of sustainability have been proposed. Many authors have been concerned with only part of the problem, such as the technological assumptions, the ability to substitute natural resources in economic transformation processes, and the resilience and importance of ecological processes. But, the social dimension did not receive the same attention, and has not been adequately integrated into formal analysis. The engineering community has to play an important role in sustainable development with appropriate evaluation of the engineering systems. In this respect energy, water and environment systems require multi-criteria evaluation methods for the assessment of the economic, environmental and social aspect of the systems.

Inhaltsverzeichnis

Frontmatter

Sustainability Development in Energy Strategy

Advantage of the Renewable Energies at Madeira Island: Electrical Power Production

The electro-producter system at Madeira Island, includes a thermoelectrical power station, nine Hydroelectrical power stations and four private wind parks, with a total effective power of 180,7 MW, being 125,8 MW installed in Vit00FC;ria Power Station, 49,5 MW in the several hydroelectrical power stations and the remainder 5, 34 MW in the wind parks, representing 69,6%, 27,4% and 3,0% respectively, of the total effective power.

Mário J. Fernandes, Agostinho Figueira, José Cotrim
Sustainability Assessment of Renewable Energy Systems

The paper presents an attempt to select, define and apply the sustainability set of indicators for the energy system assessment. Starting from the general concept of sustainability it is defined the set of indicators reflecting specific criteria for the energy system evaluation. The particular attention is devoted to the resource, environment, social and economic criteria. Among these group of criteria there are individual indicators emphasising respective aspect of the sustainability concept. Obviously, this type of approach has its limitation due to the lack of data for the serious consideration of the system. But it should be anticipated that these excises might serve as the guidance for the eventual future application. Also, it should be emphasised that this type of methodology for the assessment of energy system will become useful tool only if it proves to be justified in the engineering practice. The example under consideration is an island with only individual consumption to be satisfied with solar, wind, biomass and oil fired power plant which represent four options under consideration. The set of indicators is defined and determined with the aim to demonstrate the method of decision making procedure in selecting the option which meet specified numerical values of selected indicators and constrain reflecting the non-numeric information of weighting factor for the determination of general criteria for the selection of appropriate option.

Naim H. Afgan, Maria G. Carvalho, Nikolai V. Hovanov
Design and Optimization of Forced Convection Heat Sinks for Sustainable Development

The development of forced convection heat sinks for microelectronic applications, which are compatible with sustainable development, involves the achievement of a subtle balance between a superior thermal design, minimum material consumption, and minimum pumping power. Due to the rapid proliferation of electronic systems, substantial material streams and energy consumption rates are associated with the cooling of computers, as well as other categories of electronic equipment. The study reported herein explores the potential for the least-energy optimization of forced convection cooled rectangular plate heat sinks. Analytical models are used to determine the thermal performance of such heat sinks, for pressure drops in the range of 20 to 80Pa and flow rates between 0.01 and 0.04 m3/s. The results are evaluated in terms of a heat sink Coefficient of Performance, relating the cooling capability to the energy invested. Guidelines for "sustainable" heat sink designs are suggested.

Avram Bar-Cohen, Suzana Prstic, Kazuaki Yazawa, Madhu Iyengar
Bioenergetics—Conversion of Biochemical to Mechanical Energy in the Cardiac Muscle

Life is sustained by the continuous conversion of biochemical energy to mechanical energy, which is required to maintain the various functions of living organisms. This wide range of energetic activities depends on rotary and linear molecular (protein) motors of nanometer scale, which propel (bacteria, sperms), transport (messengers in neural network, cell division) generate high-energy metabolites (ATPsynthase) and perpetuate motion (muscle shortening).This study relates to the linear molecular motor, myosin, which is energized by ATP (adenosine triphosphate) hydrolysis, and actuates muscle filament contraction. The actin-myosin filaments make up the intracellular contractile apparatus, the sarcomeres, and their relative motion, sliding one over the other, determines the functional characteristics of the contracting heart muscle.The study explores the relationship between the biochemical energy consumption and the mechanical output of the motor units of the heart muscle. The analysis is based on coupling motor unit dynamics with free calcium binding kinetics, which regulates the motor unit activity. The calcium binds to the regulatory proteins of the contractile filaments and regulates the number of activated myosin motor units. The analysis quantifies the conversion efficiency and the determinants of the muscle’s economy. The intracellular interplay between efficiency and economy determines the adaptability of the heart muscle to the prevailing loading conditions. The analysis highlights the intracellular mechanisms and the adaptive processes that allow the heart to optimize its function under various loading conditions.Whereas the thermodynamic efficiency of the overall metabolic transformation from biochemical energy to mechanical energy of the whole organ is 25–35%, the efficiency of energy transduction from ATP to mechanical energy ranges between 50 to 70%. This high efficiency of energy conversion reflects the extremely high efficiency of the myosin motor unit, wherein the ATPase enzyme is instrumental in ATP hydrolysis ATP + H2O ↔ ADP+P reaction and the production of mechanical energy. Finally, we discuss the notion that man is challenged by nature’s functional design in his pursuit of new horizons.

Samuel Sideman, Amir Landesberg
Comparison Between Simea and Seneca Methods for Social Impact Analysis of Energy Systems

The SIMEA (Social Impact Method of Energy Analysis) and SENECA (Social and ENErgetic Change Analysis) are new methodologies to evaluate social impact, considering as environment not only the natural world, but also the economy structure, social organisation end cultural and historical aspects of a site. The aim of SIMEA is to consider in integrated way most of the possible effects on the environment (considering the definition of enlarged environment: nature, economy etc.) of the energy system and evaluate the social consequences on site where the energy system is installed of this effects as social impact. The SENECA method aims at evaluating the social change coming out from different energy choices within energy development projects in small rural communities. Through this method is possible to describe both an implemented and an implementing project using some indicators and a correlation, giving justification of the appropriate use of the chosen function. Aiming at the common scope of Social impact evaluation of energy systems, SIMEA and SENECA will use parameters that are chosen in different ways. In both cases the site is analysed from a social point of view starting from energetic changes. The surrounding areas are considered in different ways. For SIMEA it is only considered as parameter for the comparison to evaluate the local situation. SENECA method is based on a gravitational model, so that the surrounding areas are the gravitational field itself, and the migration flux, or the repulsive force, are based also on it.

F. Orecchini, A. Micangeli, I. Pollini, A. Santiangeli, L. Del Campo, F. Zuccari
Sustainable Energy Scenarios Using Green Energy for India

Energy sources are a vital factor for any developing country like India. To aid in its economic growth, the energy source should be sustainable and renewable energy is one such option. However, it is found that its contribution in India has declined over the years. Recently an impetus has been given by the Government of India to boost its application. An optimization model, which minimizes the cost-efficiency ratio subject to various constraints on demand, social acceptance, potential, reliability, emission and employment has been developed. This model indicates an increase in solar energy consumption at about 2005–06. In these early years, around 2005–06, bio-resources and wind is found to be the major contributors. In the later years, during 2020–21, solar energy and direct combustion of biomass together, will contribute around 78% of the total renewable energy. Parameters like reliability, potential, employment, emission and demand are varied and their effect on the model is studied. The study reveals that if the reliability of wind increases, the contribution would increase to 7.1% in 2020–21 from the present value of 3.1%. Technological innovations are also needed in the solar energy sector to make this source a competitive one.

L. Suganthi, A. Williams
Assessing Urban Environmental Sustainability by Means of Indicators: The Case of the Heritage Buildings

Man in developed countries is looking for new and more suitable paradigms of a correct evolution, founded on an improved level of quality of life, on a pollution-free environment and on the availability of rising amount of time to be spent in pleasure and cultural activities.

M. La Gennusa, G. Rizzo, M. Rizzo, G. Scaccianoce
Kyoto Protocol Objectives by Promoting the Technology Transfer to Small Island Developing Countries: Santo Antão, Cape Verde

Cape Verde is an example of a state that consists of several islands, with its particular energy situation. The electrical energy system is split into nine islands, and some of the islands, as well as Santo Antão, are further split into several independent electrical energy systems, which makes it hard for modern energy planning. The electricity generation is heavily dependent on Diesel engines of various powers, while on some islands there are some wind capacities installed, particularly on São Vicente. Diesel power is expensive and polluting, but still the most appropriate for such small scale electricity generation. This paper studies implications of different scenarios of development of electrical energy system on the island of Santo Antão, one of the most undeveloped and hard to electrify because of geography and lack of resources. An estimate of electricity demand for the period until 2030 is given. Business as usual scenario based on Diesel capacity is compared to two renewable energy scenarios, one envisaging 30% of the electricity generated by the wind power, and the other combining 25% of wind power with 5% of photovoltaic power. Further scenarios were generated and compared to the previous by the assumption of declining prices of renewable energy technologies. The scenarios were compared from the point of view of electricity generation prices, but also from the point of view of greenhouse gases (GHG) emissions. The possible influence of Clean Development Mechanism as a part of satisfying the United Nations Framework Convention on Climate Change objectives were assessed. A certain potential for financing the technology transfer was quantified and its influence on different electricity system planning scenarios estimated.

Neven Duic, Luís Manuel Alves, Maria da Graça Carvalho

Economic Evaluation of New and Renewable Energy Source

Constructal Optimization of Tree-Shaped Paths for the Collection and Distribution of Fluid, Electricity, Goods and People

This paper reviews a recent development in the integrative optimization of complex energy systems: the geometric optimization of tree-shaped networks that facilitate volume-point and area-point flows with minimum resistance, time, or cost. This method was originally developed in the design of conduction paths for cooling heat generating volumes, with application to the cooling of compact (volume constrained) packages of electronics. It was found that geometric form (e.g., the shape of each volume element) can be deduced from the minimization of global volume-point resistance subject to global constraints. When assembled into larger constructs, the optimized building blocks reveal a tree structure that guides the global flow with minimum resistance. This ‘constructal’ method provides a direct and extremely efficient route to the design of complex paths for flows between volumes (or areas) and discrete points. The paper illustrates the application of the method to three classes of flows that are important to the concepts of sustainable development: (i) Tree networks for fluid flow, with application to the distribution of drinking water, the collection of sewage and rain water, and the collection of oil and natural gas from wells; (ii) Tree networks for electricity, with application to the design of electric and electronic packages, the distribution of electric power over a territory, and the collection of photovoltaic current over a collector surface; (iii) Tree networks for people and goods, with application to designing geographic routes for transportation with minimum time and minimum cost between points and finite-size areas. The method is not only a valuable tool in a wide diversity of applications, but also a symbol of the integrative approach to the design and optimization of a complex energy system with diverse internal flows. Everything is considered together (e.g., volume, area) subject to global constraints, in the pursuit of global performance objectives. The design—the actual geometry of the flow structure—emerges as a result of the global optimization principle.

Adrian Bejan
An Overview of Gas Turbine Technologies for Power Generation in Europe

This article presents the three objectives of European energy policy namely mastering global change and pollution, security of energy supply and creation of employment and the enhancement of the competitiveness of the European industry. An overview of power generation with gas turbine systems is given and the European Union strategy for supporting the development of these systems is presented. Ways to improve the performance of the several types of gas turbine cycle will be a major objective in the coming years. The targets are combined cycle efficiencies above 60%, industrial gas turbine system efficiencies of at least 50%, small gas turbines efficiencies above 35% and designs for the use of fuels with less than 25% of the heating value of natural gas. A core of European projects in the field of industrial gas turbines has been formed. It is believed that the co-ordination of these activities together with the liaison with national and other projects will act as a catalyst to enhance the competitiveness of the European industry.

P. A. Pilavachi
Pricing the Energy Supplied by Renewable Sources: An Assessment of the Portuguese Situation

This paper is concerned with the independent production of electrical power based on renewable sources. Recently, new legislation has been published with the aim of creating the conditions for the renewables to become a more significant component of the generation mix. One of the main tools to enforce the increase in the penetration of renewable sources is the establishment of the so called “green tariffs”, that incorporate the environmental benefits provided by those producers. The paper is composed by three main parts. Firstly, some details concerning the Portuguese electrical system are given, including an assessment of the novel legislative framework. Then, a description of the new methodology used to compute the energy prices paid by the public system to the producers that convert renewable sources, is made. Finally, a case-study composed by three renewable installations is presented; some results concerning the processing of available data are shown, namely an estimation of the average energy selling prices from renewable producers to the public grid and the percentage distribution of the different parcels that compose the average prices.

Rui M. G. Castro, J. P. Sucena Paiva
Sustainable Utilization of Paper Sludge for Energy Conversion: Economic Potential and Environmental Feasibility

In the context of sustainable development, the assessment of the role the paper industry is of paramount importance. In the last years, the efforts of the paper industry towards ecologically sustainable paper recycling have faced growing problems of waste management since recovered paper processing leads to the production of considerable amount of waste (sludge) requiring disposal. The work outlines the current state of the utilisation of paper sludge for energy conversion. Focus of the paper is the assessment of the environmental feasibility of energy recovery from paper sludge associated with toxic emissions (like NOx, SO2, N2O, chlorinated organic compounds); the fate of some toxic metals (like Hg, Pb, Cd, Zn, Mn) deriving from dyes, fillers, and toxic pigments is discussed based on new research combustion data. The environmental impact of burning paper sludge is discussed showing the interdependence between sludge properties and combustion conditions. Recent data concerning co-combustion of paper sludge, particularly in conjunction with different biomass fuels (like wood and straw), are reported. Differences related to usage of paper sludge as a fuel in paper mill boilers and industrial power plants and their economic implications are presented. Future possible scenarios for paper sludge utilisation in energy recovery are also discussed.

Beatrice Coda, Roland Berger, Klaus R. G. Hein
Cost Optimization of a Cogeneration Plant

The software package for optimization of the cost of the thermal power plant operation was developed. The plant supplies hot water for district heating, process steam for industry and electric power. The mathematical model of the plant includes four steam generators, two back-pressure turbines and other equipment like heat exchangers, deaerators and pressure reduction valves. Two optimization approaches were tried. The first one used a general-purpose optimization solver that may be found in commercial packages, without satisfactory results. The second one was the self-developed solver reflecting the design philosophy of the plant. The optimization package was tested against the plant custom operation modes. For this purpose the consumption data for two month, typical for winter and summer mode of plant operation, were chosen. In both cases cost savings ranging from 0.8% to 5.5% have been obtained.

Zeljko Bogdan, Drazen Loncar, Nikola Serman
An Integrated Methodology for Regional Energy Planning in Isolated Areas: Application in the Cape Verde Islands

Isolated areas face significant power supply problems, due to the lack of domestic conventional energy resources as well as due to the fact that the connection to the continental electricity grid is often not economically viable. In addition, the lack of economies of scale, due to the small dimension of the energy market, results in the high installation and operation costs of the power supply system, as far as the per capita consumption is concerned. However, substantial renewable energy sources are present in many of the isolated areas and in particular in islands, that can enable local development, contribute to the reduction of dependence on energy imports and the minimisation of CO2 emissions. To this end, the paper presents an integrated methodology for regional energy planning aiming at the optimisation of the power supply system through the penetration of renewable energy technologies. Last, the application in Santo Antão Island, Cape Verde, and the results obtained through the Power Information System, developed under the concept of the proposed methodology, are presented.

Dimitris Th. Askounis, Argiris G. Kagiannas, John Psarras
Modern Financial Mechanisms for Renewable Energy Technologies

The main barrier in the application of innovative renewable energy technologies locates mainly in the investment scarcity as well as in the limited awareness of the operation and function of alternative modern financial mechanisms. The financial risk of the conventional financing schemes (i.e lending schemes, equity financing, etc.) combined with the increased technological and performance risk of advanced renewable technologies consist additional inhibit to the development of RES projects. The promotion of renewable technologies will be enhanced by the application of modern financial mechanisms which provide a series of alternative advantages, including the decrease of the impact of the risks entailed in the conventional financing schemes, as well as attractive terms to potential investors and to energy users. The present paper presents an analytical overview of the most important modern financial mechanisms aiming to contribute to the development and wider application of renewable energy sources.

Dimitris Th. Askounis, Argiris G. Kagiannas, John Psarras
Advanced Sustainable Integrated Systems for Total Building Energy Supply

The paper will discuss a number of new technologies for total building energy supply and describe the progression from single energy generator to integrated space and water heating and power generation systems. Currently, the residential and commercial buildings are being constructed with a high level of insulation, which significantly lowers the space heating loads; at the same time the recyclable building materials have been increased drastically. This progress has provided opportunities for new, innovative approaches to be applied to the mechanical system design. The paper will discuss the current commercialized integrated space and water heating systems, the residential fuel cell co-generation system and self-powered systems involving such technologies as thermophotovoltaics and thermoelectrics for limited power generation on-site.

Evgueniy Entchev
Assessment of Renewable Energy Sources Using a Geographical Information System

The choice between different Renewable Energy Technologies to provide a given Energy Service, is based on the analysis of the best linkage between local Renewable Energy Sources, (RES) technical aspects of each Renewable Energy Technology, and the specific characteristic of the Energy Demand. Commonly, this analysis should prove that selected technical system is in compliance with current market choice, socio-economic and environmental concerns and in agreement with available legislation.RES are determined by the capacity and respective value of the primary energy available and its spatial location. Technical assessment of the energy resources means evaluation of the potentiality for its use as energy source under competitive conditions. For distributed system the spatial location of Energy Demand is important to improve Renewable Energy Technologies capability to compete with centralized options. The spatial location of the Potential Energetic Demand requires the localisation of the potential consumers and the quantification of their need and expectation.Geographical Information Systems (GIS) are useful tool for Renewable Energy Sources and Energy Demand assessment. GIS is currently used in Environmental and Resources Management as a Decision Support System and Simulation tool. Common sectors for GIS application are Water resources and Air Quality Management. Hydroelectric Energy as an aspect of water resources management was the first Renewable Energy to take advantage of GIS capabilities. Biomass energy can also be integrated in land use and Agricultural Resources Management. Some methods to assess Wind and Solar Resources have been developed and applied in different countries and recently, the availability of geological and hydrologic maps lead to the use of GIS in Geothermal Resources as well. This paper describes a methodology for Renewable Energy Assessment using GIS and its application to Cabo Verde Islands.

Anildo Costa, Cláudio Monteiro, Vladimiro Miranda, Luís M. Monteiro Alves, Maria GraÇa da Carvalho
Kyoto Protocol Objectives in Croatia Energy Planning

Croatia as an Annex I country of the United Nations Framework Convention on Climate Change (UNFCCC) and a country that has pledged in the Annex of the Kyoto Protocol to reduce its greenhouse gases (GHG) emissions by 5% from the pre-transition level by the budget period 2008–12, will have to envisage a new energy strategy. Compared to the energy consumption collapse in some transitional countries like Russia and Ukraine, Croatia has passed through a relatively limited long term reduction of GHG emissions since 1990 because of higher efficiency of its pre-transition economy. It is expected that in case of business as usual scenario it will breach the Kyoto target in 2003 since the demand for energy will be high, especially as the income continues to rise, especially in domestic use for heating, for transport and for electricity generation. Several scenarios of developing energy system are compared from the point of view of GHG emissions. Business as usual scenario covers the planned gasification of coastal Croatia. In the transport sector no GHG reduction compared to the business as usual scenario is expected, unless there are technology innovations on global automotive industry level. The energy sector that will most probably be the most influenced by the UNFCCC objectives is electricity generation. Several scenarios are compared. The cost-effective scenario expects a mixture of coal and gas fired power plants to be built to satisfy the new demand and to replace the old power plants that are being decommissioned. More Kyoto friendly scenario envisages avoiding the construction of the most of the future fossil fuel power plants, while decommissioning the old ones as planned, and is compared to the others from the GHG emissions point of view. The conclusion is that by measures tackling only electricity generation it will not be possible to keep GHG emission under the Kyoto target level.

Neven Duić, Franjo Juretić, Mladen Zeljko, Željko Bogdan
Renewable Energies in the Canary Islands: Actual Situation and Perspectives

The Canarian Archipelago is formed by seven islands and it is located 60 miles from the African coast and 750 from Cádiz, in the parallel 28. At the end of 1996 the Canary Islands had 1.605.400 inhabitants, and last year it received approximately 10.000.000 tourists. These facts confer special connotations which make the Canary Islands different from the rest of the European territory.Firstly, due to its geographical configuration, it has six autonomous electrical grids. Each island has there own small dimension electrical grid —weak grids- and the islands are very far away from the big supplying centres. If we also take into that there are no conventional energy resources on the islands, we realise that external energy dependency is almost complete. For the Canary Islands it is very important to increase the level of energy self-sufficiency. This can one be done developing renewable energy sources, mainly wind and solar energy.At the end of 1999 the percentage of RE power connected to the grid represented only about 5% (but in terms of electricity production was around 3%). This RE contribution comes mainly from wind energy (representing more than 98% of the RE connected to the grid).There is also another characteristic which represents the different situation of the Canary Islands: the high energy consumption for water production (mainly coming from desalination plants).In the Canary Islands a big effort is being doing in order to increase RE contribution, develop 100% RE communities and trying to couple desalination plants with RE. Part of this work is presented in this paper.

Julieta Schallenberg
Results of an Experimental Investigate of Natural Ventilated Building

Climatization and natural ventilation concepts are today in most countries considered as an essential aspect of the building project. In fact they are utilised to guarantee the summer thermal comfort and the indoor air quality control. Besides there are many others vantages as the low use of the energy, the reduction of noise levels and an easy plant maintenance. In the last years the use of the hybrid ventilation systems in the office buildings has been developed. The aim of the present work is to value the fluidodynamic phenomena connected to the running of the air conditioning and natural ventilation system in a innovative building, constructed in central Italy, to realise the energetic optimisation and to reach the thermal comfort conditions.An innovative building has been monitored and the main fluidodynamic parameters data of the air have been recorded. Besides the recorded values have been connected with the external parameters, as solar radiation, wind speed and direction, and so to verify the indoor conditions due to the energetic behaviour of building and to the outdoor environment.This research has been realised with an automated apparatus for indoor data acquisition and a meteorological station equipped with the probes to measure the external environmental parameters.In this paper the results obtained during the operating of the building are present.

P. Principi, C. Di Perna, E. Ruffini
Safety Assesment of Hydrogen as a Fuel for Vehicles by Numerical Simulation

In this paper a study of safety aspects of liquid and compressed hydrogen fuel for road vehicles is presented. The study is performed using numerical tools, which allow easier parameter modification than experiments. Such studies are needed to build up credibility in hydrogen used as energy carrier.

H. Wilkening, A. G. Venetsanos, T. Huld, J. G. Bartzis
Possibilities of Reducing Energy Costs by Using CHP Systems in Urban Area of Sarajevo Region

Rational use and efficient energy production was not enough introduced in the prewar period and what is the most important, the relevant Governmental departments did not do anything to establish that as an obligation for large consumers. It was one of the reasons why the price of any product and service, because of high participation of energy in the costs, was very high and not competitive in the market. After the war in Bosnia and Herzegovina the situation has changed. To be competitive in manufacturing and servicing, a lot of companies and institutions started to count, more seriously, not to save energy, but to reduce the costs of energy production and to use it rationally. One of possible and perhaps the most attractive way of rational energy production and usage, without large investment and as very quick application, is small scale CHP system (Combined Heat and Power production system). This paper deals with CHP systems implementation within the Sarajevo region and with the presentation of benefits of their using in accordance with: more efficient fuel consumption relating in reducing the costs of any production or service and consequently, making them competitive, because of decreasing of energy participation in them. Three characteristic projects are included, showing the benefits expected from their implementation. Those projects are: Gas Mixing Plant for peak shaving in Gas Consumption, Application of CHP Systems on Existing and new gas generators in City Bakery, City and State Hospital and Central Heating System and as the most interesting using for Sanitary Landfill Gas in Sarajevo Sanitary Landfill. For all the mentioned projects, this paper presents some details which would be useful as an idea for application on the similar systems in underdeveloped countries. The main point presented in the paper is techno-economical background of the projects and their influence on the global energy system of the users.

T. Sadovic, N. Delalic

Solar Energy Utilisation

Expert System for New and Renewable Energies

In an energy market where the energy networks reach almost all the sites, as the European one, the continuity of the required energy supply is perceived as a “must” from the end users. The number and the temporal extension of any “black out” along the year is regarded as a qualifying parameter to evaluate the performance of each Utility. As a matter of fact a renewable energy source, like solar energy or wind, isn’t every time available at the same level along the day and/or the year, so an expensive backup system has to be foreseen to allow them to be competitive. If systems that exploit renewables are linked to an existing grid, as the electric one, or share the same equipment to produce usable energy (as a boiler that can burn either gas or biomass) they become integrated systems, and the renewables can be exploited when and where they are available. Thank to the synergy among renewable-based energy systems and the conventional ones, the energy markets can take advantage of the naturally existing diversity. This diversity arises both from the integration of a range of technologies, each with its own temporal variations (“when”), and from naturally geographical diversity of the resources (“where”). The development of an analysis about the possibility to integrate renewable based energy systems, requires a global evaluation of the interaction among the proposed technological choices, economical aspects and social effects assume a relevant role. The high number of independent variables that has to be considered and the difficulty of modelling some entities and their relationships bring this type of problem in the field of the “complex problems”, that can managed only by skilled people. Usually, many actors are called to work in planning the features of an energy system, as decision makers, politics of local or central administrative bodies, utility executives, etc., but is not assured that the involved people are totally able to master these activities. Since the potential request (and so the potential market) for tools that can support the decision process in this framework appears as interesting, a Decision Support System (DSS) is under development at CIRPS — University of Rome “La Sapienza” aimed at helping to assess the possibility to integrate renewable energy based plants within the energy system of a European Region. The goal of the project is to design an expert system that could help the user in the evaluation of the potential for an integration of renewable energy sources within selected European Regions, in the assessment of the impacts of their exploitation and in supporting the choice among different possibilities. This paper presents an overview of the activities related to the development of the tool, highlights the baseline of the project, the desired targets versus the acquired ones, the main difficulties encountered and the actions performed to overcome them. The aim is to analyse, through the experience gained, the opportunities to use expert systems and expert system based tools in energy planning.

Fabio Orecchini, Riccardo Del Po, Vincenzo Naso
Photovoltaics R&D: A Tour Through The 21st Century

The future investments for photovoltaics research & development are contemplated for this new millennium. Current technologies are used as the foundation for what might be anticipated for the next 50 years. A ‘tour’ is conducted through what we and our coming generations can envision for this technology emphasizing numerous non-conventional applications beyond the “expected”. Next-generation research approaches are predicted indicating the horizon of PV technology. Speculation about PV and related technologies that are beyond this horizon are presented, with prognosis what our coming generations might have as their ‘conventional’ solar electricity and energy sources.

Lawrence L. Kazmerski
The Use of Solar Energy in a District Heating System in Finland: Case Study of Six District Heating Plants

This paper presents a case study of the technical and economical potential to use solar energy in the Finnish district heating system. The function of a district heating system connected solar collector field was simulated with the TRNSYS simulation program. As a result of the simulations some basic figures could be found: the solar gain in a Finnish district heating plant integrated solar collector field, the typical outgoing temperatures from the solar heat, the maximum power output and the average power output. Heat could be abstracted from the solar collector field from March to October. Without storage 2–3% of yearly heat production could be obtained with solar collectors. With short-term storage the solar collectors could provide 10% of yearly heat production. Also the competitiveness of solar district heating was studied. The results indicate that considering the cost of solar heating systems and the fuel prices today, the district heating system integrated solar heating is not yet cost-effective in the Finnish circumstances, especially as the expected pay-back periods tend to be very short. The competitiveness of solar heat in Finland will improve, if the fuels are taxed by the level of the pollution they cause, if their prices go up, or if the prices of the solar collectors come down. The subventions offered to promote the use of the renewable energy sources may also play a significant part in improving the competitiveness of solar district heating in Finland.

Mia Leskinen
Solar Air Conditioning for Buildings

In mediterranean countries hotels, hospitals and other public buildings apply air conditioning in the summer time. Present trend is for a continuous increase in the rate of penetration of air conditioning in new and existing service and public buildings. The result is a continuous increase in electricity demand and an increase in the electric peak load, because most of today’s air conditioning systems applied are based on vapour compression refrigerating systems electrically driven.Due to the fact that the cooling demand is simultaneous to the solar radiation it is expected that an integrated energy supply system consisting of flat plate collectors, an absorption refrigerating machine (ARM) in connection with a cogeneration system based on an internal combustion engine and/or a boiler can reduce the electricity demand and fossil fuel can be substituted through solar energy.The humid climate and an extended cooling season, which is typical of mediterranean countries, offer a lot of advantages to solar cooling. In particular, the use of collectors is not limited to a short season of a few months of the year. If cooling is to be included in an application of solar energy, it is obvious that the investment in the cooling system will be put to greater use in this climate.Subject of the paper is to discuss the possibility of saving fossil fuel through system examination and management of the solar driven absorption system. Finally the maximum solar collector prices will be estimated in a way that the system can be operated economical compared to compression refrigerating systems.

Ingo Romey, Gisbert Markert
Experimental Study of a Passive System: A Ventilated Wall

Experiments were carried out on a passive thermal system built in Toulouse, France. The study is dealing with ventilated walls. The walls were made up of vertical hollow terra-cotta bricks. One wall was used as a reference. In the case of the second, the first row of cavities was 220cm high and open at its ends. Results obtained from data collected from April to October 1999 show that the open vertical slots allow removing part of solar radiation.

S. Lorente, M. Bégué
Overall Performance of Advanced Glazing Windows in Nonresidential Buildings: Heat Extraction and Energy Requirements

Industries in these last years have developed and produced different types of transparent materials and light control systems to improve the design and the operation of buildings to take full advantage of the energy saving potential coming from daylight. Building energy demand assessment requires an integrated approach of the visual and thermal management, that is realized both by the automatic control systems and by the occupants which can override control systems to suit their own comfort requirements. This paper analyses the HVAC cooling design peak and the energy demand connected to the use of advanced glazing materials in conjunction with light control systems for a typical office room in Mediterranean climate. The approach is based on an hourly simulation program IENUS (Integrated ENergy Use Simulation), that integrates environment visual and thermal aspects. IENUS implements thermal aspects by the transfer function method for a Typical Meteorological Year (TMY) and visual aspects by the computer package Super lite. Heat extraction peak and seasonal energy consumption are analyzed for different glazing systems, daylight control strategies with and without occupants interaction.

F. Gugliermetti, L. Grossi
Photovoltaic Solar Cells With Thin Film Materials

Transparent thin layers of SnO2 and ZnO and absorbing materials like CuInSe2 and porous silicon have been deposited on glass or silicon substrates by different techniques of deposition as chemical vapour deposition (CVD), spray pyrolysis, flash evaporation and electrochemical anodization. Deposition parameters such as temperature substrate, deposition time or annealing parameters for SnO2 or spray time, deposition temperature or solution concentration for ZnO were varied. The polycrystalline films were found to exhibit wurtzite structure for SnO2, hexagonal structure for ZnO and chalcopyrite structure for CulnSe2. A preferential orientation of the grains appears when substrate temperature was varied. The thickness of the films was measured by Talystep instrument, interferential microscopy and from the peaks of transmission spectra. Variation of electrical conductivity with deposition parameters was analysed. The deduced activation energy depends on thermal annealing. In order to derive refractive index and coefficient absorption, reflectance R and transmittance T were measured. Heterojunction solar cell has been fabricated by deposition of tin oxide on monocrystalline silicon.

N. Kesri, R. Outemzabet, A. Zouaoni
Photovoltaic Devices: A 2000 Overview

The status and directions of current photovoltaic technologies are presented. The emphasis is on the cell and module performances, with indications of the limitations and strengths of crystalline (Si and GaAs) and thin-film (Si, a-Si:H, CdTe, Cu(In,Ga)(Se,S)2) approaches. Recent advances in concentrator technologies, promise of thin films, and the continuing commercial dominance of crystalline Si photovoltaics are evaluated and considered in their evolution for this new century.

Lawrence L. Kazmerski

Fuel Cells Development

Suitability of Metallic Materials for Interconnects in Solid Oxide Fuel Cells

FeCr model alloys with variation of chromium content, reactive element addition and spinel forming elements were studied in respect to oxidation resistance at 800°C. Additionally, in-situ studies were carried out to characterize the high temperature conductivity of the formed surface oxide scales. Based on these results, two model steels and a commercial material, alloy 446, were selected tor further qualification. First tests in respect to oxide scale formation, oxide conductivity, formation of volatile species and compatibility with contact materials showed potential suitability of these steels as construction material for SOFC interconnect.

W. J. Quadakkers, J. Piron-Abellan, V. Shemet, L. Singheiser
Fuel Cell Buses: A Sustainable Technology for the Urban Passenger Transportation Sector

The main objective of the present papers is to present a sustainable and environmental alternative solution for the passenger transport systems. The solution is based on the fuel cell technology and will be presented under a Thermie demonstration project sponsored by the European Union entitled “Fuel Cell Bus Berlin, Copenhagen and Lisbon.” The project involves the design and construction of a completely new bus by MAN that will use stacks of fuel cells supplied by Air Liquide. The fuel selected for operating the bus is liquid hydrogen stored in two cylindrical vessels at -253° C under a pressure of ca. 4 bar.The bus will be monitored by a team of Instituto Superior Técnico, Lisbon and demonstrated for several months in the three major cities of Europe: Berlin, Copenhagen and Lisbon. Demonstrations will be executed using the local main transportation companies that will incorporate the fuel cell bus into their normal lines. The bus will be tested initially for a period of nine months by the Berlin Bust transportation company — BVG in the city of Berlin on the route between the airport and the city center. The bus will also undergo test runs in Copenhagen for one month operated by HT and in Lisbon for two months operated by CARRIS. Of special interest in these test runs will be how factors such as climate and geography (e.g. flat/hilly terrain) can influence the fuel cell bus. The project will demonstrate advantages of fuel cell buses compared to conventional diesel buses. The performance of the test runs will by analyzed in relation to inner city conditions. Economic data such as vehicle reliability, technology, operation and fuelling will be gathered as part of a process to establish the market viability of this technology. The project will be accompanied by a comprehensive measurement program which will clearly show the environmental benefits to be gained from the introduction of a technology which provides a 100% reduction in emissions. This will help to convince potential users of fuel cell technology of its benefits in inner urban applications.

P. P. Pinto, A. M. Brasil, T. L. Farias, R. Lemke
Fuel Cells and the Future of Motorization

Petroleum as main raw material to production of practical fuels in car engines, is not source of renewable energy. Besides, in result of fuels combustion produced from petroleum (petrol, diesel oil) are emitted pollutants to earth’s atmosphere. Therefore in automobile concerns are realized intensive development works, aiming to diminution of fuel consumption and restrict of issue pollutants. Alternative sources of energy to drive cars, which would be able to take place with success of petroleum derivative fuels also are searched. Fuel cells are doubtless of these solutions, which can in nearest future to revolutionize drive systems in car vehicles.In article kinds of fuel cells and their principle of operation has been described. Physical-chemistry parameters of these cells are also compared. In recapitulation prognosis for fuel cells- in context development of motorization in the future has been formulated.

Kazimierz Lejda
Fuel Cell-Based Renewable Energy Supply: Sustainable Energy for Isolated and Island Communities

There are large opportunities for the operation of fuel cells with renewable fuels in isolated and island communities. Hydrogen can be produced from the electrolysis of water using solar, wind and hydro electricity, while other fuels can be produced from the thermo-chemical or biological decomposition of biomass and waste. These can be upgraded to hydrogen or cleaned and used directly in fuel cells. Renewable fuel cell-based energy can be used in stand-alone or grid connected applications. It can provide independent power or complement variable renewable energy sources. Also, it can improve the economic and environmental performance of renewable energy systems and provide significant environmental and often economic benefits over non-renewable alternatives.

Ausilio Bauen, Flavio Foradini, David Hart
Sustainable Heat and Electricity from Sugarcane Residues Gasification in Brazil

Sugarcane residues, in the form of bagasse and cane tops and leaves, represent a large renewable biomass energy resource in Brazil. Bagasse is currently used to satisfy the energy needs of the sugar and alcohol industry with poor efficiency and poor environmental control. Advanced conversion technologies, such as biomass integrated gasification combined cycles (BIG/CC), can lead to high conversion efficiencies and significant improvements in environmental performance. The use of cane tops and leaves, in addition to bagasse, could add significantly to the energy produced. There is then a large potential for sugarcane mills to act as economically viable decentralised power plants selling electricity to the grid. Furthermore, the power produced may present important environmental benefits compared to conventional alternatives.

Ausilio Bauen

Biomass and Waste Energy Utilisation

Some Aspects Contributing to Improved Process and Equipment Design in the Field of Waste-To-Energy and Environmental Protection

Waste-to-energy technology (WTE) is also referred to as thermal processing of wastes including energy utilization. It means not only combustion of various types of wastes (incineration) in order to substantially reduce their volume is performed but also WTE systems can provide us with clean, reliable and renewable energy. A number of conditions of sustainable development in the process industry involving waste-to-energy systems can be formulated. Some criteria which can play a decisive role are discussed (economic and efficient process design, global heat transfer intensification, efficient selection of utilities including combined heat and power systems, using WTE systems, design of efficient equipment, local heat transfer intensification etc.). Relations between process, waste and energy are shown as well as relations between an improved process design and equipment design. Some examples from the field of heat exchangers (a new type of shell-and-tube heat exchanger, optimisation of plate type heat exchangers, and a new type of heat recovery steam generator) and their contribution to economic and environmental characteristics are demonstrated. It is shown that units for the thermal treatment (and/or processing) of wastes are used not only for the purpose of disposal of various types of wastes but also for recovering the heat by generating steam and electricity or for preheating purposes (WTE). Some examples (multipurpose incinerator for processing solid wastes, unit for processing sludge originating in the pulp and paper plant) including a WTE plant structure are described.

Petr Stehlík
Generation of a Gaseous Fuel by Pyrolysis or Gasification of Biomass for Use as Reburn Gas in Coal-Fired Boilers

Biofliels attract increasing interest in power plant technology as sources of carbon dioxide neutral fuels. Besides using solid pulverised biomass as an additional fuel in coal-fired boilers a further possibility to run a combined coal and biomass process is to pre-pyrolyse or pre-gasify biomass and to inject the gas as reburn fLiel into the coal-fired boiler. Within the pre-tre atment process the solid feedstock is separated into a high energy gas and a solid residue. The gas can be used as a reburn fuel in the coal-fired boiler with excellent NOx reduction properties. The separation of coal and biofiiel ash within this process enables a specialised use of both residuals.At the Institute for Process Engineering and Power Plant Technology the pyrolysis and gasification of different biomass has been investigated with special emphasis on the gas, tar and char composition and on the NOx reduction efficiency of the produced gas. The gasification experiments have been carried out in an electrically heated lab-scale entrained flow reactor in understoichiometric atmosphere, for the reburn experiments a pulverised fuel combustion reactor was available. The gas, tar and composition as well as the NOx reduction efficiency have been analysed at temperatures of the entrained flow reactor between 400°C and 1300°C and of the fluidised bed reactor between 600°C and 900°C and air ratios of the pyrolysis/gasification process between 0 and 0,4.Detailed results of the investigations using pyrolysis gas from coal [7,8], sewage sludge [17] or biomass [18] for NOx reduction are published elsewhere. To get information about the path of different feedstock components during pyrolysis the quality and quantity of pyrolysis char depending on temperature has been analysed and reported in [17, 18].

C. Storm, H. Spliethoff, K. R. G. Hein
Phase Space Description of Unstable Dynamics of a Lean Premixed Gas Turbine Combustor

This work describes unstable phenomena of a lean premixed gas turbine combustor considering the geometrical properties in a phase space representation. Several experiments have been performed in which the air excess ratio λ and the percentage of pilot fuel PFP have been varied. The time series of experimentally measured pressure and heat release fluctuations inside the duct have been analysed using vectors collecting topological parameters of the attractors of experimental acoustical and optical sensors. Therefore, unsupervised Kohonen associative memories have been trained to create clusters of operating conditions characterised by similar dynamical behaviours. The results of the clustering underline the practical possibility of defining an algorithm for instability pattern recognition, which could be effective for either a diagnostic or a control system.

Alberto Fichera, Cinzia Losenno, Arturo Pagano
Integrated Biomass Gasification - Gas Turbine - Fuel Cell Systems for Small-Scale, Distributed Generation of Electricity and Heat

The use of a biomass gasifier that drives a gas turbine integrated with a fuel cell, is a potentially very attractive way to generate electricity and heat with a high efficiency and very low emissions. The application of catalytic combustion systems can decrease the emissions even further.A number of technical and non-technical developments during the last 5 years have significantly enhanced the opportunities for small-scale, distributed power generation, especially for systems based on biomass fuels. These developments are: the liberalisation of the energy market, the growing needs for electricity and heat in developing countries, the increasing demand for ’green’ or ‘sustainable’ electricity, the near-commercial availability of maintenance-low micro-turbine generator packages and developments in the field of high temperature fuel cells.Preliminary system studies have shown that the integration of the different subsystems needs careful evaluation in order to realise the expected high efficiencies. To enable the assessment of the technical feasibility of potentially attractive system designs, adequate, experimentally validated knowledge with regard to biomass gasification, pressurised combustion of the fuel gas and the gas cleaning steps is required.Possible system designs based on a combination of electrochemical and thermochemical fuel conversion steps are examined and analysed with regard to efficiency, emission and costs.A system design for application on commercial scale based on present day technology will be considered. At Delft University of Technology, a biomass gasifier has been set up and a conceptual design for a pilot system, to be tested in the slipstream of the Delft 1.5 MWth process development unit, will be presented. The process development unit is described in more detail in [Hoppesteyn, et. al., 1998] and [de Jong et. al., 1998]. In this study, it has been attempted to integrate an SOFC with an existing micro gas turbine that has not especially been adjusted for the integration with the SOFC.

B. J. P. Buhre, J. Andries
Thermodynamic Performances and Cost Analysis of Advanced Biomass Combustion Power Plants

The use of biomass for power production reveals a growing worldwide interest, due to the strategic role it has for environmental concerns, large availability and technological advances. As a raw material, biomass contains relatively high moisture, requiring thermal drying processes in order to limit energy losses at the stack.In this paper, plant configurations with different options for drying the biomass before combustion have been discussed. Conventional indirect processes, using steam extracted from the turbine, and direct drying processes, performed through hot gases at the turbine exit, have been compared, highlighting their influence on plant layout and performance. Moreover, a thorough economic investigation has been carried out for evaluating the levelized cost of the produced electricity, as well as the profitability of each solution.The study shows that the biomass drying through recovered thermal energy from gas turbines improves the biomass power plant feasibility. It allows for enhancing performances and reducing biomass plantation extensions with respect to conventional solutions. The analysis also demonstrates that the proposed solutions allow for lowering the cost of the produced electricity and for shortening the payback periods.

Roberto Carapellucci
Stabilizing Effect and Diffusion Control on Diffusion Flames by Magnetic Field

Diffusion control and stabilizing effect on diffusion flame of propane gas were found in a magnetic field. Magnetic field strength was changed at 0.11.38xl05A/m at the center of the field. Experiment of diffusion control was carried out with a nozzle of 8-mm diam. Experiments of stabilizing effect were carried out with a nozzle of 2-mm diam. These nozzles were set at the center position of the uniform magnetic field and propane gas was run through with these nozzles at a constant flow rate. Property of propane gas and flame are diamagnetism, on the other hand air and oxygen gas are paramagnetism. Particularly volumetric susceptibility of oxygen gas is very large value. The magnetic pressure on flames was attributed to paramagnetic (air) and diamagnetic (flame) properties. As magnetic field was applied, the flame changed from an oscillating flame to a stable flame with a low frequency and small oscillating amplitude. The stabilizing effect was examined by temperature and luminosity measurement by observation with the schlieren method and high-speed photographs. The width of the outer swelled combustion gas region became narrower and keeps a constant width when the magnetic field was applied. In the condition that magnetic field was not applied, when oxygen gas was injected coaxially in the outer nozzle as secondary flow of gas, the length of the diffusion flame changed extremely short. Under this condition when magnetic field was applied, the flame length increased with increasing in magnetic field. This means that the diffusivity of oxygen gas can be controlled by magnetic field. In this study, flow control of fuel and stabilizing effect to oscillating flame are proved by using magnetic field. These effects were expressed by pressure acting on the flame by magnetic force.

Hidenori Tanaka, Koji Yoshida, Motoaki Kimura, Hideo Shoji, Mitsugu Uehara, Atsushi Saima, Morimasa Higaki
Experimental Study on Combustion in a Porous Media

Continually increasing use of fossil fuel now represents the greatest danger for planet Earth, as result of ever increasing C02 emission in the atmosphere. Development and use of modern technologies for combustion of fossil fuels and of very efficient systems for heat exchange in a useful form permit increased energy efficiency while maintaining or increasing the level of comfort, with decreased emission of CO, NOx. One such technology is the system of burner-heat exchanger based upon combustion in porous media. The paper describes the burner and the construction of a test rig and the measuring equipment that was employed in the study. This work presents the advantages of this system, relating to the high thermal loads of porous media in the reaction zone (4MW/m2), high power density of the system with porous media of burner-heat exchanger (7MW/m3), extremely good thermal conductivity of porous media and very high thermal capacity, very stable combustion with large range of power modulation (as high as 1:20), high efficiency of transforming fuel into energy (105% relating to the lower heating value of fuel). Through increased energy efficiency there were lower CO2 emission and very low CO, NOx emissions (“near-zero emission”). Because of these advantages, the system is very applicable to central heating systems of residential buildings, heating of water for sanitation purpose, etc.

N. Delalić, E. N. Ganić, M. Likić
Low Emission Combustion of Vegetable Oils with the Porous Burner Technology

The porous medium burner technology is based on the combustion inside three- dimensional cavities of an inert porous medium, where the combustion process is enhanced by all the three mechanisms of heat transfer: conduction, convection and radiation. Compared to conventional combustion processes using free flames, the porous medium combustion has the following advantages: low NOx- and CO-emissions due to lower and controllable combustion zone temperatures,wide, infinitely variable dynamic power range of 1:20 while conventional state of the art premixed burners show a power range of 1:4,high power density of up to 4 MW/m2 and 40 MW/m3 under atmospheric pressure,high combustion stability over a wide range of equivalence ratios.Due to these outstanding properties, the porous medium burner technology is attractive for a wide range of applications. One of them is the combustion of C02- emission neutral vegetable oils. Vegetable oils contain an enormous variety and number of different molecules, so that complete evaporation or gasification without any residuals in premixed burners is a very challenging task. Thus, systematic studies of controlled vegetable oil evaporation were carried out to make vegetable oils available as a fuel for porous medium combustion. The main result of these studies is, that vegetable oil evaporation without any residuals is not possible, but there are operating windows with acceptable low residual levels. For the practical realisation of vaporisers a suitable cleaning procedure through at least partial oxidation was developed, which uses air oxygen for partial oxidation under elevated temperature. A porous medium burner was constructed, which contains two vaporisers, so that one vaporiser can be cleaned while the other provides vegetable oil vapour for burner operation. Thus, continuous operation of the system can be achieved by cleaning the vaporisers mutually from time to time.

A. Bakry, B. Genenger, V. Schmidt, D. Trimis
Emissions during the Co-combustion of Lignite and Waste Wood in a Fluidised Bed Reactor

Co-combustion tests were performed in a lab-scale fluidised bed reactor, in order to define (a) the optimum percentage for substituting Greek lignite by waste wood, and (b) the operation conditions ensuring complete burnout of the fuel blends. Tests were performed at the experimental facility of the NTUA’s Steam Boilers and Thermal Plants Laboratory (NTUA-LSB). Pre-dried lignite, from Ptolemais reserve, and various waste wood species, i.e. uncontaminated wood, demolition timber and railway sleepers, were used to prepare the fuel blends. In all tests, the emissions in flue gases - CO, SO2, N2O, NOx, NO, NO2 and CXHY — were continuously monitored.The combustion efficiency, gaseous emissions and residual matter composition were measured for the various fuel blends, considering also the excess air ratio effects. Ash samples, collected during the co-combustion tests, were analysed, at AUTh-CPERI, in an ICP-AES spectrophotometer for heavy metals. Furthermore, a qualitative assessment for the ash deposition propensity, including measurements of the characteristic ash-fusibility temperatures of various fuel blends was accomplished. The results obtained, proved that waste wood addition in the fuel blend, up to a certain percentage, is feasible. Furthermore, the minimal ash content and sulphur percentage of waste wood contribute to the minimisation of ash agglomerates formation during the co-combustion with the low quality lignite

E. Kakaras, P. Vourliotis, P. Grammelis, G. Skodras, P. Samaras, G. P. Sakellaropoulos
Combustion of Sawdust

In Finland new drying and combustion devices that enable the use of sawdust or wood pellets instead of oil in municipal scale power boilers with only slight changes to the boiler have been developed. The two plants in operation in Finland at the moment using the new CMR-burner for biomass produce district heat with thermal powers of 1 and 2.5 MW, respectively.In this study the combustion of sawdust in the above-mentioned device is investigated by modelling a 3D case with a commercial software. The code includes a group of special subprograms, including one for the pyrolysis of particles and for their trajectories. Still, for several features such as the prediction of the reaction rates as well as the particle source terms appropriate submodels have to be coded and implemented to the program.The combustion takes place in two stages, i.e. primary air is fed into the burner together with fuel while secondary air is fed into the after-burning zone further in the furnace. The size distribution of the sawdust particles is quite wide, ranging from around hundred micrometres to several millimetres. The moisture content of the fuel varies between 10 and 20%. Primary air and fuel are fed in with a very high swirl while secondary air has a considerably weaker swirl. The highly swirling flow field in the burner has a significant effect on the mixing process and on the particle trajectories. Thus, in addition to chemical reactions also the flow field has to be modelled as accurately as possible. In this case the RNG k-e model was chosen. The reaction rates for the pyrolysed phase are mainly calculated by the EDC reactor technique while for the nitric oxide formation the Arrhenius-type equation with mean values is used. The combustion of the pyrolysed fuel is modelled with the simple two-step mechanism.The subprograms include a number of different parameters mostly related to fuel properties some of which have to be evaluated due to lack of exact knowledge. In spite of this, the calculated results seem to be in quite a good agreement with the experimental data available.

Maarit Talvitie, Sanna Sierilä, Antti Oksanen, Markku Miettinen
Design and Calculation of a New Unit for Thermal Treatment and Energy Utilization of Gas Wastes

This paper presents a comprehensive theoretical as well as experimental investigation of a new incineration unit for thermal treatment of volatile gases diluted in air. The unique design of this unit is described, using an actual experimental device, which has been constructed to further investigate design and operational options of this new equipment. A simplified mathematical model and a CFD simulation of the unit are presented. The experimental and modeling results are discussed and compared and some conclusions are drawn. Directions of further research on this new equipment modeling and design are defined.

Vlastimil Fabikovic, Roman Stulir, Jiri Hajek, Petr Stehlik, Jaroslav Oral
Development of Computerized Tool for Design and Assessment of Biomass Power Generation Systems

This paper describes the development of a general highly flexible PC based computerized tool for the steady-state analysis of thermal power system design and performance analysis. This tool can be used for analyzing biomass gasification based power systems. Biomass-fueled power generation system often involved more advanced processes such as pyrolysis, gasification and fluidized bed combustion and novel cycle schemes. With this computerized power cycle analysis tool, the user can model any proposed power system and perform analysis to produce information on power plant operating performance at “design” or “off-design” operating conditions. One added feature of this computerized analysis tool is the inclusion of a software package for the economic assessment of the power generation system.

Jing T. Kuo
Thermochemical Gasification of Biomass: Fuel Conversion, Hot Gas Cleanup and Gas Turbine Combustion

Air-blown fluidized bed biomass gasification integrated with a gas- and steam turbine combined cycle (BIGCC) is a potentially attractive way to convert biomass into electricity and heat with a high efficiency.There exist a number of technical uncertainties with regard to this option which have to be understood better and in more detail before industrial-scale systems can be designed, optimized, controlled and assessed with regard to technical feasibility and costs.Some of the design choices which cannot be made convincingly on the basis of currently available knowledge are: atmospheric versus pressurized gasification, bubbling versus circulating fluidized bed, dry versus wet gas cleaning, in-bed or ex- bed tar removal and required gas turbine modifications.All of these choices have an impact on operational issues like the fate of Nitrogen components, tar, alkalies, trace components, gas turbine combustion, dynamic behaviour and control. To be able to predict the influence of the system choices on these issues, validated, reliable and possibly mechanistic models, simulating the relevant processes, are needed.A 1.5 MWth Process Development Unit which contains the main ‘active’ components of a BIGCC, is used to obtain experimental data which are needed to develop and validate models. The PDU basically consists of a dedicated compressed air-supply system, three independently controlled solids feed systems, a pressurized bubbling fluidized bed gasifier, a high temperature ceramic filter and a gas turbine combustion section equipped with a pressurized heated air supply system, simulating compressor air. In the current configuration the hot pressurized gas, coming from the hot ceramic filter, is directly entering the gas turbine combustor. Experimental results with regard to the fate of different components during their passage through the complete system are presented and discussed.

J. Andries, W. de Jong, P. D. J. Hoppesteyn, Ö. Ünal, K. R. G. Hein
The Use of Waste Wood for Energy Production: Technical Aspects and Management Issues

This paper presents technical aspects and management issues of wood waste reuse and disposal. It refers to the Greek and European legislation which determines the framework for rational and environmental friendly practices for wood waste management. It refers also to the wood waste classification systems and the currently applied methods of wood waste disposal and reuse. Emphasis is given to the wood waste-to-energy conversion systems, particularly to the pretreatment requirements, the combustion techniques, and the environmental constrains. Finally, the decision-making process for investments in wood waste fired thermal units is discussed.

E. Kakaras, E. Karlopoulos, F. Pavloudakis
Disposal of Low Calorific Value Waste Gas

The utilisation of waste methane off gases from the ventilation of mines and water supplies was investigated. Waste gases with methane in air contents from 0.5–3% were investigated using a staged combustion system with a lean well-mixed radial swirier as a main burner with the secondary fuel and the waste gas as the premixed primary fuel carrying fuel and oxygen to the main burner. The radial swirl burner had low NOx well mixed combustion characteristics, using radial swirl vane passage fuel injection. The tests were carried out on a 76mm outlet diameter swirler with a dump expansion into a 140mm diameter combustor. The test flow conditions were at an isothermal Mach number of 0.02 at 600K inlet temperature. These conditions are representative of gas turbine combustion applications as well as process burner operating conditions. The results showed that the premixed waste gas promoted the combustion stability of the main burner. This enabled leaner overall combustion to be sustained, with reduced NOx emissions. The waste gas was completely burned with very low NOx, HC and CO emissions. All the energy content of the waste gases was recovered for all methane contents of the waste gases.

M.C. Mkpadi, G.E. Andrews, I.A. Khan

Geothermal and Ocean Energy Utilisation

Modified Thermal Calculations of a Geothermal Double-Pipe Heat Exchanger (with Insulation And No Insulation) Immersed into Geothermal Deposit

Kujawa, Nowak and Szaflik [3, 4] presented an approximate analytical methods of calculation for the Field exchangers with insulated and no insulated top part with intermediate fluid. In this work the authors modified the method of calculations for the Field exchanger. In this method a boundary condition assuming equal temperatures at the turning point was calculated during determining integration constants. That allows one to get an analytical relation, which enables to directly determine the temperature field of fluid in the heat exchanger. That operation simplified the calculations of output heat and cut down the time of the calculations. The authors also analysed the influence of main parameters on the temperature field as well as on an output heat flow by intermediate fluid in a geothermal exchanger.

Tomasz Kujawa, Wladyslaw Nowak
Ocean Thermal Energy Conversion (OTEC) and Deep Ocean Water Applications (DOWA): Market Opportunities for European Industry

The IOA International OTEC/DOWA Association, an association created in 1990, aims at informing on worldwide R&D efforts to develop the commercial usage of DOW - Deep Ocean Water. In the past IOA interest for DOW has been focused on its use as the cold source in the OTEC process for supplying electricity. IOA’s review of the most recent results obtained (mainly in USA, Japan, India and Taiwan) indicates that the Deep Ocean Water should be now considered as a renewable resource for “clean” production of many commercial products including not only electricity but also fresh water, food, energy saving, air-conditioning, etc. Technologies to tap into these resources are available and OTEC/DOWA facilities can contribute to the development of isolated coastal areas located in the tropical belt and some sub-tropical areas. But OTEC/DOWA according to the criteria adopted by the European Union Commission for defining the priorities of its Fifth Framework Program has not yet reached the status of “already developed technology” as do wind, photovoltaic, biomass, and other energy resources located in the European continental region.This presentation makes a case for the European Union Commission to carefully assess the full potential of OTEC/DOWA and support its development as it already represents: a) export markets opportunities for European industry, b) opportunities for the development of European Overseas Territories, and c) potential supply of synthetic fuel to respond to Europe’s own future demand for primary energy and world sustainable development.

Michel Gauthier, Lars Golmen, Don Lennard
On the Two-Phase Dispersed Flow Hydrodynamics and Heat Transfer Investigations

Details of two experimental sets for droplet deposition in vertical upward air—water dispersed flow are presented: stainless steel and Plexiglas test section — together with typical experimental results, using different liquid concentrations and mean droplet sizes. The results obtained for different gas Reynolds numbers, ranging from 4xl04 to 9.5x 104, are given. The measurements of deposition showed that commonly used assumptions about the effect of droplet concentration on increase in droplet size, and decrease in droplet turbulence cannot completely explain the observed decrease of the deposition coefficient with increasing droplet concentration. Better agreement was obtained by taking into account the effect of the droplet sticking ratio (probability of sticking) to the wall. It is suggested that the presence of the liquid film causes a decrease in droplet sticking ratio.An experiment is described on two-phase dispersed heat transfer. Wall temperature distributions are presented for a uniformly heated stainless steel test section.

Š. Šikalo, N. Delalić, E. N. Ganić
Spreading of Droplets on Horizontal Surfaces

We present experimental results on the impact of single droplets on dry, solid surfaces. The investigation concentrates on the effect of the surface wettability and the effect of the viscosity of the droplet liquid on the spreading process. To characterize the wettability effect, surfaces of glass and wax with different static contact angles are used. To characterize the effect of viscosity the spreading of water and glycerin droplets are compared. To characterize the effect of the surface tension the spreading of isopropanol (liquid with low surface tension) and water droplets are compared. Experiments are performed for different impact velocities. The droplet Weber number varies between 50 and 1080, the Reynolds number varies between 27 and 14800. The results are presented in the form of charts describing the spreading diameter and apex height of droplets in terms of time.The surface wettability has been observed to have a strong influence on the spreading of the droplets in the later stages of the process. The viscosity effects the spreading velocity and maximum spreading diameter. The splash of an isopropanol droplet occurs at a lower critical Weber number than for a water droplet. It was found that liquid droplets on rough surfaces splash at a lower critical Weber number than for a the smooth surface.

Š. Šikalo, C. Tropea, M. Marengo, E. N. Ganić
Air Particulate Matter Characterization of an Industrial Area at North From Lisbon

Since 25th January 1999 airborne particulate matter samples have been collected in three stations located at the North outskirts of Lisbon. The samples are analysed by two nuclear analytical techniques: Neutron Activation Analysis (INAA) and Particle Induced X-Ray Emission (PIXE). The multielemental characteristics of the two techniques used (INAA and PIXE) and its complementarity makes it possible to determine concentration for 37 elements. In this work mass concentrations obtained by gravimetry will be compared to the actual legislation and EPA limit values. Results for Lead, Chromium, Copper, Manganese, Nickel, Arsenic, Cadmium, Mercury, Potassium, Antimony, Vanadium and Zinc will be presented and compared in reference values.

S. M. Almeida, M. C. Freitas, M. A. Reis, M. M. Farinha
Backmatter
Metadaten
Titel
New and Renewable Technologies for Sustainable Development
herausgegeben von
Naim Hamdia Afgan
Maria da Graça Carvalho
Copyright-Jahr
2002
Verlag
Springer US
Electronic ISBN
978-1-4615-0296-8
Print ISBN
978-1-4613-5009-5
DOI
https://doi.org/10.1007/978-1-4615-0296-8