Showing papers in "Renewable & Sustainable Energy Reviews in 2000"

Renewable energy and sustainable development: a crucial review

Abstract: Achieving solutions 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. That is why there is an intimate connection between renewable energy and sustainable development. Anticipated patterns of future energy use and consequent environmental impacts (focussing on acid precipitation, stratospheric ozone depletion and the greenhouse effect) are comprehensively discussed in this paper. Also, potential solutions to current environmental problems are identified along with renewable energy technologies. The relations between renewable energy and sustainable development are described with practical cases, and an illustrative example is presented. Throughout the paper several issues relating to renewable energy, environment and sustainable development are examined from both current and future perspectives. It is believed that the conclusions and recommendations drawn in the present study will be useful to energy scientists and engineers and policy makers.

Triglycerides-based diesel fuels

Abstract: Efforts are under way in many countries, including India, to search for suitable alternative diesel fuels that are environment friendly. The need to search for these fuels arises mainly from the standpoint of preserving the global environment and the concern about long-term supplies of conventional hydrocarbon-based diesel fuels. Among the different possible sources, diesel fuels derived from triglycerides (vegetable oils/animal fats) present a promising alternative to substitute diesel fuels. Although triglycerides can fuel diesel engines, their high viscosities, low volatilities and poor cold flow properties have led to the investigation of various derivatives. Fatty acid methyl esters, known as biodiesel, derived from triglycerides by transesterification with methanol have received the most attention. The main advantages of using biodiesel are its renewability, better-quality exhaust gas emissions, its biodegradability and given that all the organic carbon present is photosynthetic in origin, it does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the greenhouse effect.

Fast pyrolysis processes for biomass

Abstract: Fast pyrolysis for production of liquids has developed considerably since the first experiments in the late 1970s. Many reactors and processes have been investigated and developed to the point where fast pyrolysis is now an accepted feasible and viable route to renewable liquid fuels, chemicals and derived products. It is also now clear that liquid products offer significant advantages in storage and transport over gas and heat. These advantages have caused greater attention to be paid to fast pyrolysis, leading to significant advances in process development. The technology of fast pyrolysis for liquids is noteworthy for the wide range of reactor configurations that have been developed to meet the stringent requirements for high yields of useful liquids, for use as a fuel in boilers, engines and turbines and as a source of chemical commodities. This review summarizes the key features of fast pyrolysis and the resultant liquid product and describes the major reaction systems and processes that have been developed over the last 20 years.

State-of-the-art of anaerobic digestion technology for industrial wastewater treatment

Abstract: Anaerobic digestion is the most suitable option for the treatment of high strength organic effluents. The presence of biodegradable components in the effluents coupled with the advantages of anaerobic process over other treatment methods makes it an attractive option. This paper reviews the suitability and the status of development of anaerobic reactors for the digestion of selected organic effluents from sugar and distillery, pulp and paper, slaughterhouse and dairy units. In addition, modifications in the existing reactor designs for improving the efficiency of digestion has also been suggested.

Wind energy technology and current status : a review

Abstract: The paper provides an overview of the historical development of wind energy technology and discusses the current status of grid-connected as well as stand-alone wind power generation worldwide. During the last decade of the 20th century, grid-connected wind capacity worldwide has doubled approximately every three years. Due to the fast market development, wind turbine technology has experienced an important evolution over time. An overview of the diAerent design approaches is given and issues like power grid integration, economics, environmental impact and special system applications, such as oAshore wind energy, are discussed. Due to the complexity of the wind energy technology, however, this paper mainly aims at presenting a brief overview of the relevant wind turbine and wind project issues. Therefore, detailed information on further readings and related

World Bank/GEF Solar Home Systems Projects : experiences and lessons learned 1993-2000

Abstract: Twelve projects provide energy services to off-grid rural households in developing countries by enhancing markets for solar home systems and by removing barriers to their dissemination. Project approaches are reviewed, along with early implementation experience and lessons suggested by experience. Most projects incorporate the following features: pilot private-sector and NGO delivery models; pilot consumer credit delivery mechanisms; pay first-cost subsidies and offer affordable system sizes; support policy development and capacity; develop codes and standards and establish certification, testing, and enforcement institutions; and conduct consumer awareness and marketing programs. Most projects are just beginning implementation; a few are almost completed. Lessons from early experience suggest that: solar home system delivery firms face a myriad of difficulties operating in rural areas; credit risk is a serious concern of both financiers and dealers and makes credit sales particularly challenging; technical performance of systems is becoming well-proven; customers desire a range of component options and service levels and can benefit from even small systems; projects must recognize the link between rural electric-grid extension and solar home system demand; and marketing campaigns can be extremely costly and time consuming in rural areas. Challenges are to demonstrate sustainable and replicable business models, develop regulatory models for energy-service concessions, and integrate rural electrification policy with solar home system delivery.

Ground heat transfer effects on the thermal performance of earth-contact structures

Abstract: A review of ground heat transfer effects on the thermal performance of earth contact structures is presented. The fundamental heat transfer processes relevant to the problem are described along with methods of determining thermal properties of soils. An overview of the many analytical, semi-analytical and numerical methods available to solve the heat transfer problem is also provided, followed by a brief summary of design guides. The review also considers the influence of changes in ground water content on the heat transfer properties of soils. A description of the processes that give rise to changes in ground water conditions is provided. The bulk thermal conductivity of a soil is shown to be strongly related to its water content. An overview of methods of analysing changes in soil moisture content is then presented. Methods of estimating the relevant hydraulic properties of soils are also considered. The final part of the review provides a brief outline of the theoretical approach required to analyse coupled heat and moisture migration in soils. Notwithstanding the fact that there are many practical design tools available, it appears that further work is necessary to clarify the circumstances in which more sophisticated analysis is warranted. Recent studies indicate that geometric simplification can lead to quite significant errors in heat loss calculation. Full three-dimensional treatment appears to be necessary in some cases. Thermal properties of soils vary according to the properties and proportions of the constituent phases (air/water/solid). Soil moisture content variations occur naturally or as a result of anthropogenic activity. The influence of such variations on the thermal conductivity of the ground is significant. The review outlines some simplified methods of accommodating this feature of the ground heat transfer problem. However, this aspect of the problem appears to need further consideration.

Technology development in the solar absorption air-conditioning systems

Abstract: An environmental control system utilizing solar energy would generally be more cost-effective if it were used to provide both heating and cooling requirements in the building it serves. Various solar powered heating systems have been tested extensively, but solar powered air-conditioners have received little more than short-term demonstration attention. This paper reviews past efforts in the field of solar powered air-conditioning systems with the absorption pair of lithium bromide and water. A number of attempts have been made by researchers to improve the performance of the solar applied air-conditioning (chiller) subsystems. It is seen that the generator inlet temperature of the chiller is the most important parameter in the design and fabrication of a solar powered air-conditioning system. While collector choice, system design and arrangement are other impacting factors for the system operation.

Renewable energy activities in Senegal: a review

Abstract: Like many countries in Africa, Senegal is facing economical decline, energy crisis and serious desertification problem in rural areas. These issues could be removed if renewable energy is used as a primary source of energy in rural areas. What is required is a strategy to implement renewable energy technologies at large scale. The government and many non-governmental organisations (NGOs) have tried to comprehend and have strived to address the problem of energy. This paper presents a review of activities in the field of renewable energy applications in Senegal, which goes back to the mid 1970s and will discuss the socio-economic benefits that the country has derived from these environmentally sound and appropriate sources of energy. The development and trial of systems were mostly funded so far by donor agencies in collaboration with government and NGOs. Among the applications being supported are solar lighting, water pumping and small power plants. Recent efforts have been aimed at restructuring the programmes and giving them a market orientation. Future trends, some suggestions and recommendations for successful dissemination of renewable energy sources are also drawn. The present situation is seen to be much more promising and favourable for renewable energy.

Present and prospective role of bioenergy in regional energy system

Abstract: Bioenergy is the energy released from the reaction of organic carbon material with oxygen. The organic material derived from plants and animals is also referred to as biomass. Biomass is a flexible feedstock capable of conversion into solid, liquid and gaseous fuels by chemical and biological processes. These intermediate biofuels (such as methane gas, ethanol, charcoal) can be substituted for fossil based fuels. Wood and charcoal are important as household fuels and for small scale industries such as brick making, cashew processing etc. The scarcity of biofuels has far reaching implications on the environment. Hence, expansion of bioenergy systems could be influential in bettering both the socio-economic condition and the environment of the region. This paper examines the present role of biomass in the region’s (Uttara Kannada District, Karnataka State, India) energy supply and calculates the potential for future biomass provision and scope for conversion to both modern and traditional fuels. Based on the detailed investigation of biomass resource availability and demand, we can categorise the Uttara Kannada District into two zones (a) Biomass surplus zone consisting of Taluks mainly from hilly area (b) Biomass deficit zone, consisting of thickly populated coastal Taluks such as Bhatkal, Kumta, Ankola, Honnavar and Karwar. Fuel wood is mainly used for cooking and horticulture residues from coconut, arecanut trees are used for water heating purposes. Most of the households in this region still use traditional stoves where efficiency is less than 10%. The present inefficient fuel consumption could be brought down by the usage of fuel efficient stoves (a saving of the order of 27%). Availability of animal residues for biogas generation in Sirsi, Siddapur, Yellapur Taluks gives a viable alternative for cooking, lighting fuel and a useful fertiliser. However to support the present livestock population, fodder from agricultural residues is insufficient in these Taluks. There is a need to supplement the fodder.

Humankind’s detour toward sustainability: past, present, and future of renewable energies and electric power generation

Abstract: Renewable energies have been the primary energy source in the history of the human race. During the last 200 years, industrialized countries have shifted their energy consumption toward fossil fuels. Contemporary electric power generation is based on non-renewable resources such as oil, coal, and nuclear power. New efficient and cost-effective small-scale renewable energy generation options are commercially available today. Market distortions are to be overcome in order to make renewable energies cost-competitive in today’s economic environment. Social, environmental and also economic reasons will reverse the worldwide primary energy use back to renewables and thus reapproach a sustainable economic system based on traditional and new high-tech technologies.

The role of public policy in emerging green power markets: An analysis of marketer preferences

Abstract: Green power marketing has been heralded by some as a means to create a private market for renewable energy that is driven by customer demand for green products. This article challenges the premise — sometimes proffered in debates over green markets — that profitable, sizable, credible markets for green products will evolve naturally without supportive public policies. Relying primarily on surveys and interviews of US green power marketers, the article examines the role of specific regulatory and legislative policies in ‘enabling’ the green market, and searches for those policies that are believed by marketers to be the most conducive or detrimental to the expansion of the green market. We find that marketers: (1) believe that profitable green power markets will only develop if a solid foundation of supportive policies exists; (2) believe that establishing overall price competition and encouraging customer switching are the top priorities; (3) are somewhat leery of government-sponsored or mandated public information programs; and (4) oppose three specific renewable energy policies that are frequently advocated by renewable energy enthusiasts, but that may have negative impacts on the green marketers’ profitability. The stated preferences of green marketers shed light on ways to foster renewables by means of the green market. Because the interests of marketers do not coincide perfectly with those of society, however, this study also recognizes other normative perspectives and highlights policy tensions at the heart of current debates related to green markets. By examining these conflicts, we identify three key policy questions that should direct future research: To what extent should price competition and customer switching be encouraged at the expense of cost shifting? What requirements should be imposed to ensure credibility in green products and marketing? How should the green power market and broader renewable energy policies interact?

Ecological approach for the evaluation of intelligence energy features in a building's skin

Abstract: The recent development of ‘intelligent’ features and techniques for buildings’ skins are intended to meet certain energy targets. These targets are rarely looked at in an integral way. Research in this area aims to reduce energy consumption as a consequence of using certain intelligent features. The importance of such features in a wider environmental scope is often ignored. This paper attempts to set criteria based on the energy flow principles in integral natural systems to evaluate the energy performance in an intelligent skin and relates to a certain definition of ‘intelligence’ in buildings’ skins, drawing a list of features that can reflect this definition. A list of 23 carefully chosen buildings has been prepared as case studies to check the developed criteria. Different weights for different criterion are calculated for various features based on the ecological energy principles. The conclusion refers to the variations in adopting certain intelligent features in different parts of the world.

Two year experience in the operation of the first community photovoltaic system in Cuba

Abstract: Although the photovoltaic technologies have been introduced in Cuba for more than 10 years, the long-term stable operation is still an aspiration. With the setting in operation of the first community photovoltaic electrification system, it was possible to carry out a systematic study of the factors that determine the loss of quality of the operative state of the systems by means of the detection and classification of failures detected in periodic technical inspections. The data analyzed on the basis of the medium frequency of failures allowed discovering problems of technology and its social adoption. This analysis leads to the design of a system for maintenance and repair that guarantees the sustainability of the project. The technical characteristics of the equipment that adapts better to the real conditions of exploitation in the country were determined as well.

A market diffusion potential (MDP) assessment model for residential energy efficient (EE) technologies in the U.S.

Abstract: The Diffusion of Residential Energy Efficient (EE) Technologies has been studied for many years. Finding ways to bridge the energy efficiency gap and increase the diffusion of these technologies have been of much interest to researchers and practitioners alike. However, in most studies, diffusion is equated to adoption of EE technologies by consumers. The present study tries to break this mindset and develops a model to assess the diffusion of residential EE technologies from the market's perspective. The model assesses diffusion of an EE technology based on the market's ability to provide benefits to customers that are identified to be most important. The research contributes in several ways to the existing knowledge bank of residential EE technology diffusion. It provides an elaborate literature review on market attributes with associated components that help to develop the market attributes. The model allows to identify low rating attributes and helps to improve Market Diffusion Potential (MDP) MDP of technology cases by taking appropriate actions. Also, sensitivity analysis provides a snapshot of hypothetical situations that help decision makers to realize what to expect in case of extreme market situations and improve MDP of residential EE technologies by selecting appropriate business inclination strategy for excelling. The model can have several practical applications. The results of MDP assessment would aid in market transformation, utility program selection, as well as feed in information for R & D on prospective EE technologies and a wide array of other organizations with diversified interests in energy savings, climate change and sustainability.