Showing papers in "Renewable & Sustainable Energy Reviews in 2006"

Technical aspects of biodiesel production by transesterification—a review

Abstract: Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst. The process of transesterification is affected by the mode of reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalysts, reaction time and temperature and purity of reactants. In the present paper various methods of preparation of biodiesel with different combination of oil and catalysts have been described. The technical tools and processes for monitoring the transesterification reactions like TLC, GC, HPLC, GPC, 1H NMR and NIR have also been summarized. In addition, fuel properties and specifications provided by different countries are discussed.

A review of energy models

Abstract: Energy is a vital input for social and economic development of any nation. With increasing agricultural and industrial activities in the country, the demand for energy is also increasing. Formulation of an energy model will help in the proper allocation of widely available renewable energy sources such as solar, wind, bioenergy and small hydropower in meeting the future energy demand in India. During the last decade several new concepts of energy planning and management such as decentralized planning, energy conservation through improved technologies, waste recycling, integrated energy planning, introduction of renewable energy sources and energy forecasting have emerged. In this paper an attempt has been made to understand and review the various emerging issues related to the energy modeling. The different types of models such as energy planning models, energy supply–demand models, forecasting models, renewable energy models, emission reduction models, optimization models have been reviewed and presented. Also, models based on neural network and fuzzy theory have been reviewed and discussed. The review paper on energy modeling will help the energy planners, researchers and policy makers widely.

Distributed energy generation and sustainable development

Abstract: Conventionally, power plants have been large, centralized units. A new trend is developing toward distributed energy generation, which means that energy conversion units are situated close to energy consumers, and large units are substituted by smaller ones. A distributed energy system is an efficient, reliable and environmentally friendly alternative to the traditional energy system. In this article, we will first discuss the definitions of a distributed energy system. Then we will evaluate political, economic, social, and technological dimensions associated with regional energy systems on the basis of the degree of decentralization. Finally, we will deal with the characteristics of a distributed energy system in the context of sustainability. This article concludes that a distributed energy system is a good option with respect to sustainable development.

Residential cogeneration systems: Review of the current technology

Abstract: There is a growing potential for the use of micro-cogeneration systems in the residential sector because they have the ability to produce both useful thermal energy and electricity from a single source of fuel such as oil or natural gas. In cogeneration systems, the efficiency of energy conversion increases to over 80% as compared to an average of 30–35% for conventional fossil fuel fired electricity generation systems. This increase in energy efficiency can result in lower costs and reduction in greenhouse gas emissions when compared to the conventional methods of generating heat and electricity separately. Cogeneration systems and equipment suitable for residential and small-scale commercial applications like hospitals, hotels or institutional buildings are available, and many new systems are under development. These products are used or aimed for meeting the electrical and thermal demands of a building for space and domestic hot water heating, and potentially, absorption cooling. The aim of this paper is to provide an up-to-date review of the various cogeneration technologies suitable for residential applications. The paper considers the various technologies available and under development for residential, i.e. single-family (

Desiccant cooling air conditioning : a review

Abstract: In this paper, the principles underlying the operation of desiccant cooling systems are recalled and their actual technological applications are discussed. Through a literature review, the feasibility of the desiccant cooling in different climates is proven and the advantages it can offer in terms energy and cost savings are underscored. Some commented examples are presented to illustrate how the desiccant cooling can be a perfective supplement to other cooling systems such as traditional vapour compression air conditioning system, the evaporative cooling, and the chilled-ceiling radiant cooling. It is notably shown that the desiccant materials, when associated with evaporative cooling or chilled-ceiling radiant cooling, can render them applicable under a diversity of climatic conditions.

A review of flow and heat transfer characteristics in curved tubes

Abstract: The performance of heat exchangers can be improved to perform a certain heat-transfer duty by heat transfer enhancement techniques. In general, these techniques can be divided into two groups: active and passive techniques. The active techniques require external forces, e.g. electric field, acoustic or surface vibration, etc. The passive techniques require fluid additives or special surface geometries. Curved tubes have been used as one of the passive heat transfer enhancement techniques and are the most widely used tubes in several heat transfer applications. This article provides a literature review on heat transfer and flow characteristics of single-phase and two-phase flow in curved tubes. Three main categories of curved tubes; helically coiled tubes, spirally coiled tubes, and other coiled tubes, are described. A review of published relevant correlations of single-phase heat transfer coefficients and single-phase, two-phase friction factors are presented.

Wind powered pumped hydro storage systems, a means of increasing the penetration of renewable energy in the Canary Islands

Abstract: A significant number of islands have found themselves obliged to place restrictions on the penetration of renewable sourced energy in their conventional electrical grid systems. In general, this has been due to certain energy related characteristics often connected to their very nature as islands. These limitations attempt to prevent the appearance of problems that might affect the stability and safety of the electrical system. The restrictions imposed on the direct penetration of wind sourced energy in the conventional grids of the Canary Islands are an obstacle to meeting the renewable energy objectives set out by the European Union. As a partial solution to the problem, this paper proposes the installation on Gran Canaria island (Canarian Archipelago) of an appropriately administered wind powered pumped hydro storage system. The results obtained from the application of an optimum-sized economic model of such a system indicates that penetration of renewable sourced energy can be increased by 1.93% (52.55 GW h/year) at a competitive cost for the unit energy supplied. These results are obtained on the hypothesis that two of the largest existing reservoirs on the island (with a difference in height between the two of 281 m and a capacity of some 5,000,000 m3 used in each) are employed as storage deposits. Investment, operating and maintenance costs are taken into account, as well as those costs involving health and environmental damage associated with energy production and use (externalities). The system would consist of: a wind farm with a rated output of 20.40 MW; a modular pumping station with a rated output of 17.80 MW, operated so that the variation in the energy demand for pumping is in sympathy with the wind generation; and a hydraulic plant with a rated output of 60.00 MW. The proposed system would have no negative effect on either the reliability of the electrical system or consumer satisfaction. Furthermore, it would mean a fossil fuel saving of 13,655 metric tonnes/year and a reduction in CO2 emissions into the atmosphere of 43,064 metric tonnes/year. For regions that have topographically suitable sites and which suffer energy problems similar to those of the Canary Islands it is thus suggested that an analysis be made of the technical and economic feasibility of the installation of power systems such as that proposed in this paper. Within the general guiding framework of a policy promoting clean and renewable energy, these systems represent an enormous and as yet barely explored potential.

Can microgrids make a major contribution to UK energy supply

Abstract: Almost all the electricity is generated in the UK as part of a centralised power system designed around large fossil fuel or nuclear power stations. This power system is robust and reliable but the efficiency of power generation is low, resulting in large quantities of waste heat. The principal aim of this paper is to investigate an alternative concept: the energy production by small scale generators in close proximity to the energy users, integrated into microgrids. Microgrids - de-centralised electricity generation combined with on-site production of heat - bear the promise of substantial environmental benefits , brought about by a higher efficiency and by facilitating the integration of renewable energy sources such as photovoltaic arrays or wind turbines. By virtue of good match between generation and load, microgrids have a low impact on the electricity network, despite a potentially significant level of generationby interemittent energy sources. The paper discusses the technical and economic issues associated with this novel concept, giving an overview of the generator technologies, the current regulatory framework in the UK, and the barriers that have to be overcome if microgrids are to make a major contribution to the UK energy supply. The focus of this study is a microgrid of domestic users powered by small Combined Heat and Power generators and photovoltaics. Focusing on the energy balance between the generation and load, it is found that the optimum combination of the generators in the microgrid - consisting of around 1.4 kWp PV array per household and 45% household ownership of micro-CHP generators - will maintain energy balance on a yearly basis if suplemented by energy storage of 2.7 kWh per household. We find that there is no fundamental technological reason why microgrids cannot contribute an appreciable part of UK energy demand. Indeed, an estimate of cost indicates that the microgrids considered in this study would supply electricity at a cost comparable with the present electricity supply if the current support mechanisms for photovoltaics were maintained. Combining photovoltaics and micro-CHP and a smallbattery requirement gives a microgrid that is independent of the national electricity network. In the short term, this has particular benefits for remote communities but more wide-ranging possibilities open up in the medium to long term. Microgrids could meet the need to replace current generation nuclear and coal fired power stations, greatly reducing the demand on the transmission and distribution network.

Renewable energy for sustainable development in Africa: a review

Abstract: Renewable energy usage in Africa has been reviewed using South Africa, Egypt, Nigeria and Mali as case studies. The various national energy policies of these countries were analysed and areas that require attention to achieve sustainability were highlighted. On the overall, the success of sustainable development in Africa lies in addressing the imminent energy crisis in the continent. Excessive usage of fuel wood is already creating considerable environmental problems especially in the Sahel. Africa has all the potentials to solve its energy problems if appropriate infrastructural support can be provided for harnessing the abundant renewable resources in the continent, and if skills are pooled together and experiences shared in addressing the key issues.

Techno-economic feasibility of energy supply of remote villages in Palestine by PV-systems, diesel generators and electric grid

Abstract: As a contribution to the development program of rural areas in Palestine, this paper presents three energy supply alternatives for a remote village represented in PV system, diesel generator and electric grid. Design of these systems and the associated costs of their utilization are illustrated. A computer-aided dynamic economic evaluation method with five indicators is used to compare the economic-effectiveness of these energy systems. The results show that, utilizing of PV systems for rural electrification in Palestine is economically more feasible than using diesel generators or extension of the high voltage electric grid. The obtained results represents also a helpful reference for energy planers in Palestine and justify the consideration of PV systems more seriously.

Evaluation of alternative fuels for residential heating in Turkey using analytic network process (ANP) with group decision-making

Abstract: Energy policies require cheap and continuous energy which is needed in Turkey for further development. Implementation of a successful energy policy requires political and economical institutions to take responsibility and to adopt adapt to changes easily. Energy policy generally consists of institutional structure, in which decisions related to technology, economy and energy are made, and also consists of supply–demand management in short term and planning in long term. Energy demand is closely related to social and economic structure of a society. In the long term development of energy demand, developmental structure of society (economic growth, life style, socio-economic factors), technological development and energy prices play important roles as determining factors. In this study, evaluation of most suitable fuel which can be used for residential heating was made using ANP with group decision-making.

Life-cycle energy analysis of building integrated photovoltaic systems (BiPVs) with heat recovery unit

Abstract: Building integrated photovoltaic (BiPV) systems generate electricity, but also heat, which is typically wasted and also reduces the efficiency of generation A heat recovery unit can be combined with a BiPV system to take advantage of this waste heat, thus providing cogeneration Two different photovoltaic (PV) cell types were combined with a heat recovery unit and analysed in terms of their life-cycle energy consumption to determine the energy payback period A net energy analysis of these PV systems has previously been performed, but recent improvements in the data used for this study allow for a more comprehensive assessment of the combined energy used throughout the entire life-cycle of these systems to be performed Energy payback periods between 4 and 165 years were found, depending on the BiPV system The energy embodied in PV systems is significant, emphasised here due to the innovative use of national average input–output (I–O) data to fill gaps in traditional life-cycle inventories, ie hybrid analysis These findings provide an insight into the net energy savings that are possible with a well-designed and managed BiPV system

Prospects of solar water heating for textile industry in Pakistan

Abstract: Energy is the prime source of human activities in all sectors of life. Traditionally fossil fuel has been the prime source of energy. However, there are two major concerns regarding fossil fuels, i.e. their rapid depletion and their contribution towards growing global warming. It is being widely realized that for sustainable development presently used energy mediums such as fossil fuel and nuclear power have to be quickly replaced by renewable energy sources. The latter are sustainable and have the potential to meet present and future projected global energy demands without inflicting any environmental impacts. Pakistan is amongst the most prominent cotton producing countries in the world. The affluent availability of local cotton has lead to a well-established textile sector in Pakistan. A large proportion of its cotton products go into export. Being a successful candidate in international textile market Pakistani textile industry is continuously seeking modern and high-tech facilities to improve quality of its products. The biggest challenge Pakistani textile industry is facing today is how to cut down its environmental burdens to cope with the international standards on the issue. Water heating system as required for dying process is one of the major energy consuming areas in fossil fuel-run Pakistani textile industry. Water heating system therefore has a significant contribution towards total environmental impacts associated with textile sector. This work presents an alternate, sustainable solution for water heating by means of fossil fuel. It has been shown herein that under Pakistan's climate solar energy can contribute significantly towards this duty. In the present work two different designs of built-in storage water heater—plain and newly designed finned type—were constructed to compare their thermal performance. Three months of experimental data were collected for the two heaters. The solar fractions for this period were found to be 63 and 73%, respectively. The monetary and embodied energy payback periods for the two heaters were, respectively, found to be 6.7 and 6.1 years, and 185 and 169 days.

Renewable energy policies in Turkey

Abstract: Achieving solution to environmental problems that we face today requires long-term potential actions for sustainable development. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions. Although, Turkey has substantial reserves of renewable energy resources, actual utilization of these resources are quite low. The aim of this study is to investigate the renewable energy policies and the political organizations that shape these policies. In these concept, The renewable energy potential of Turkey, the effective utilization of this potential, the energy politics, the political organizations, incentive, pricing and buying mechanisms, research and development studies, barriers for development of renewable energy are investigated in this paper. In conclusion, proposals and recommendations are given to overcome the problems.

Integrated collector storage solar water heaters

Abstract: The Integrated Collector Storage Solar Water Heater (ICSSWH) developed from early systems comprised simply of a simple black tank placed in the sun. The ICSSWH, by its combined collection and storage function suffers substantial heat losses to ambient, especially at night-time and non-collection periods. To be viable economically, the system has evolved to incorporate new and novel methods of maximising solar radiation collection whilst minimising thermal loss. Advances in ICS vessel design have included glazing system, methods of insulation, reflector configurations, use of evacuation, internal and external baffles and phase change materials.

An overview of renewable energy utilization from municipal solid waste (MSW) incineration in Taiwan

Abstract: Taiwan is an energy-importing nation with more than 97% of energy consumption supplied by imported fuels. In this regard, renewable energy like waste-to-energy is become attractive. The objective of this paper is to present an overview of energy utilization from the cogeneration system of municipal solid waste (MSW) incineration in recent years. The description is thus centered on MSW generation, incineration treatment and its energy utilization status. The energy policy relating to MSW-to-energy is also summarized in the paper. Finally, we present the regulatory system including Air Pollution Control Act, Energy Management Law and Statute for Upgrading Industries, which is not only to establish the environmental standards on MSW incineration facility, but also to provide economic and financial incentives to promote the use of MSW-to-energy.

Present status of photovoltaic energy in Turkey and life cycle techno-economic analysis of a grid-connected photovoltaic-house

Abstract: The electricity consumption in Turkey increased on average 8.5% annually between 1990 and 2000, but decreased 1.2% in 2001 due to the economic crisis of 2000. The economic growth and electricity consumption are expected to continue in a similar rate of before the crisis in the coming years. Turkey is going through a change of policy in the energy sector, adopting a policy of privatisation. On the other hand, Turkey needs adaptations in the energy field for meeting the European standards as Turkey is seeking a full membership to the European Union. The alternative and renewable energy systems have been neglected so far in Turkey but must be included in the new energy programs. The renewable energy contribution in the total primary energy production is insignificant. The current installed photovoltaic capacity is in the level of a fraction of MW, which is tiny when compared to the solar energy potential in Turkey. In this article, a photovoltaic-house, which would have photovoltaic as the main energy source, is hypothetically designed to assess the techno-economic feasibility of grid-connected photovoltaic systems in Turkey. The grid electricity is used when the photovoltaic system fails to meet the required electricity. The performance of the photovoltaic system is simulated on an hourly basis to determine the autonomy level, using one year long hourly time-series solar radiation data of Ankara obtained from the Turkish State Meteorological Service. Then, some combinations of photovoltaics and grid electricity with different buy-back ratios are analysed.

HOTRES: renewable energies in the hotels. An extensive technical tool for the hotel industry

Abstract: The project HOTRES aimed at the systematic implementation of conditions for future massive applications of the renewable energies in the tourism industry. Under the umbrella of this project five renewable energy technologies were promoted (solar thermal, solar passive, solar PV, biomass and geothermal energy) in parallel in five EU regions (East Attica, Sicily, Alpes-Maritimes, Andalusia and Madeira) by the corresponding agencies and promotion centers following an extensive and intensive work program be composed of six elaboration phases. The purpose of this article is to esteem the results achieved in the technical–economic field of the relevant extensive technical support project in 200 hotels as well as to validate the strategic methodology applied for the promotion of the renewable energy technologies (RETs) through the technical assistance of the hotel SMEs. Finally, by proving the liability and economic viability of RET applications in hotels, the largest European hotel installation with solar thermal is presented within technical and economic details.

Integration of hydrogen energy technologies in stand-alone power systems analysis of the current potential for applications

Abstract: The European study entitled: “Market Potential Analysis for Introduction of Hydrogen Energy Technology in Stand-Alone Power Systems (H-SAPS)” aimed to establish a broad understanding of the market potential for H-SAPS and provide a basis for promoting in wide scale new technological applications. The scope of the study was limited to small and medium installations, up to a few hundred kW power rating and based on RE as the primary energy source. The potential for hydrogen technology in SAPS was investigated through an assessment of the technical potential for hydrogen, the market analysis and the evaluation of external factors. The results are mostly directed towards action by governments and the research community but also industry involvement is identified. The results include targeted market research, establishment of individual cost targets, regulatory changes to facilitate alternative grid solutions, information and capacity building, focused technology research and bridging the technology gaps.

Review of the energy rating of dwellings in the European Union as a mechanism for sustainable energy

Abstract: Reducing emissions of CO2 and other GHGs is one of the biggest environmental challenges facing the European Union as it strives for sustainable development. If that challenge is to be met, domestic energy consumption must be controlled: it currently accounts for 40% of the total, making it one of the biggest sources of emissions. EU Directives 93/76 and 2002/91 make it compulsory for energy rating systems to be set up to report on consumption in buildings. This paper looks at the various rating systems now up and running, with varying levels of success, in EU countries. However, Denmark's is the only system that can be considered as providing a full energy rating in the sense of awarding a graded score to buildings rather than a simple pass/fail rating, and proposing ways of improving the score obtained. Indeed, many regulations on energy saving in the residential sector are extremely recent, and it is too soon to assess their results. In some States they may also be modified by reforms currently being studied or processed.

Review of compliance with EU-2010 targets on renewable energy in Galicia (Spain)

Abstract: The use of renewable energy offers a range of exceptional benefits, including: a decrease in external energy dependence; a boost to local and regional component manufacturing industries; promotion of regional engineering and consultancy services specialising in the use of renewable energy; increased RD increase in the level of services for the rural population; creation of employment, etc. To achieve these benefits, a series of actions are required, among which the following are particularly important: creation of a suitable climate for performing RD training of technicians in design, production and maintenance of equipment; motivation for establishing a new market; proper financing; fostering of appropriate technologies; practical demonstration of results, etc. This article reviews the progress made in the Autonomous Community of Galicia in terms of the introduction of renewable energy technologies (RETs) and examines the possibility of meeting a target of 90% coverage (practical electrical self-sufficiency) by 2010, of which 51% would come from wind power, with a saving of 4000 ktoe of primary energy, and prevented emissions of 12×10 6 t of CO 2 per year.

Wind power engineering in the world and perspectives of its development in Turkey

Abstract: The development of a world wind power for the last decade is reviewed Leading positions are taken by Germany, Spain and USA The rates of growth of this branch of power engineering exceed 39% annually It seems that the wind power is esteemed in these countries as the most perspective branch of electric power industry The great success achieved by Germany and Spain in last years in developing wind power industry served as an example for all countries that have wind energy potentials Information describing growth of powers, single wind power turbines, dynamics of increments of power of WPT on separate countries are submitted During the last 10 years, the cost of WPT construction decreased more than twice, and it seems that specific investment costs reached a stable point for about 10 years Furthermore, it can be concluded from wind farm investment costs that the cost of a WPT is about 13 times the cost of wind turbine The information on the sizes of large WPT are adduced

Damming the river: a changing perspective on altering nature

Abstract: Dams have served society for over 4500 years Through time, functions and uses have been notably altered There has been a significant proliferation in purposes for constructing dams to control stream flow and secure water storage Technological changes have been paralleled with construction of ever-larger dams to gain control of larger water supplies This study of dams is presented in the context of environment and societal needs Dams act as geomorphic agents as well as water management structures It is essential to anticipate a barrier's long-term environmental influence as well as to measure its long-term role in serving society The analysis considers the varied magnitudes of dams and their respective functions to serve ever-larger populations Dam size is a reflection of the changing dependence of society on specific water functions/services As nature has its rhythm of change, the challenge is to fit human use into nature with minimal adverse environmental impacts As with agriculture, dams have become part of the domesticated landscape

The development of urban renewable energy at the existential technology research center (ETRC) in Toronto, Canada

Abstract: This paper presents new forms of urban renewable energy, in particular, the integration of solar and wind power into the industrial and commercial buildings with flat roofs which populate a city's downtown core. This combination of renewable energy passively adapts to pre-existing structures and exploits them to their full advantage. The working prototypes presented aim to introduce an element of multi-functionality to building-integrated photovoltaics (BIPV), creating systems which produce energy while meeting required needs and desirable features of urban buildings. We also explore the combination of wind energy and various energy efficiency initiatives with BIPV designs. Our energy efficiency initiatives include a new method of generating the perception of natural sunlight from artificial light and brainwave controlled lighting that dims automatically when occupants’ concentration is lowered. These efforts result in an environment that celebrates the existential notion of self-empowerment through reducing energy consumption and having control over one's own energy production. Our discussion follows into market considerations of our BIPV designs and how project costs are lowered and space is conserved, assets when designing for urban locations. The test site for the development of urban renewable energy is the Existential Technology Research Center (ETRC), located in downtown Toronto, Canada.

Analysis and simulation on rural energy–economy system on Shouyang County in China

Abstract: A basic feedback structure of rural energy–economy system is approached in this paper based on systems engineering and system dynamics (SD) principles. The dynamics simulation model in then developed and applied in analyzing the energy construction of Shouyang County, Jiangsu Province in China. Consequently, some related policies and measures are proposed.

Empowering information and communication technologies in isolated areas: learning from the solar-net villages program in honduras

Abstract: To reduce poverty caused by inequality of opportunities in isolated areas, many developing countries are now taking advantage of recent technical advances in information and communication technologies (ICTs) to enable the remote populations to enjoy the benefits of improved commerce, education, health, and other social services. This paper describes lessons learned from the Solar-Net Villages Program (or Aldeas Solares) of Honduras with respect to its early attempts to find technological solutions for providing ICT services to isolated areas and the government's ongoing efforts to balance the objective of assisting the most disadvantaged populations with the need to have sustainable services.

Carbon emission mitigation measures in Brazil—case study of biomass policy for a ferroalloy plant in Ceará State

Abstract: The present work aims at discussing the possibilities of atmospheric carbon emissions mitigation in the scope of the United Nations Framework Convention on Climate Change (UNFCCC) in the forest sector using a case study in the Northeast of Brazil. Taking Ceara State as an example and based on the Ceara State Energy Balances for 1980, 1984 and 1987, the Carbon (C-CO 2 ) Emission Balances were drawn up covering these same years. An exercise was carried out in order to draw up carbon emissions mitigation proposals through both Environmental Education and reforestation policies replacing forest clearing. The first, environmental education and forest management practices, involves more efficient practices in the woody sector. The second, reforestation policies, instead of felling native forests for fuel-wood burned to produce charcoal, is discussed from the economic point of view. An estimate was drawn up of the carbon abatement costs, using a case study for charcoal production based on reforestation instead of deforestation, for a ferroalloy plant in Ceara State.

WITHDRAWN: Renewable Energy, 2006. International conference “advanced technology paths to global sustainability” held 9–13 October 2006 at Chiba, Japan, Makuhari Messe.

Abstract: This article has been withdrawn consistent with Elsevier Policy on Article withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). The Publisher apologizes for any inconvenience this may cause.