Showing papers on "Renewable energy published in 2004"

Overview of Applications of Biomass Fast Pyrolysis Oil

Abstract: Fast pyrolysis of biomass is one of the most recent renewable energy processes to have been introduced. It offers the advantages of a liquid product, bio-oil that can be readily stored and transported. Bio-oil is a renewable liquid fuel and can also be used for production of chemicals. Fast pyrolysis has now achieved a commercial success for production of chemicals and is being actively developed for producing liquid fuels. Bio-oils have been successfully tested in engines, turbines, and boilers, and have been upgraded to high-quality hydrocarbon fuels, although at a presently unacceptable energetic and financial cost. The paper critically reviews scientific and technical developments in applications of bio-oil to date and concludes with some suggestions for research and strategic developments.

Power Electronics as Efficient Interface in Dispersed Power Generation Systems

Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.

Energy storage and its use with intermittent renewable energy

Abstract: A simple probabilistic method has been developed to predict the ability of energy storage to increase the penetration of intermittent embedded renewable generation (ERG) on weak electricity grids and to enhance the value of the electricity generated by time-shifting delivery to the network. This paper focuses on the connection of wind generators at locations where the level of ERG would be limited by the voltage rise. Short-term storage, covering less than 1 h, offers only a small increase in the amount of electricity that can be absorbed by the network. Storage over periods of up to one day delivers greater energy benefits, but is significantly more expensive. Different feasible electricity storage technologies are compared for their operational suitability over different time scales. The value of storage in relation to power rating and energy capacity has been investigated so as to facilitate appropriate sizing.

Transforming the Energy Sector : The evolution of technological systems in renewable energy technology

Abstract: This paper analyses the development and diffusion of technologies that utilize renewable energy sources in Germany, Sweden and the NetherlandsThe analysis enlarges the life cycle model of industry evolution to one where the focus is on the formation and evolution of new technological systems Particular focus is on explaining success and failures in shifting from a formative phase into one characterized by positive feedbacks A set of challenges is identified for policy makers attempting to influence the process of transforming the energy sector

Global biomass fuel resources

Abstract: An overview of biomass for production of densified biofuels on a global scale is given. Bioenergy production as heat, electricity, and liquid fuels represents about 14% of the World's primary energy supply. About 25% of the usage is in industrialised countries and the other 75% is used in developing countries. There is an estimated 3870 (10 6 ) ha of forest worldwide. The average area of forest and wooded land per inhabitant varies between 6.6 ha in Oceania, 0.2 ha in Asia, and 1.4 ha in Europe. The world's total above-ground biomass in forests amounts to 420 (10 9 ) tonnes, of which more than 40% is located in South America. Estimates by FAO (2000) show that global production and use of woodfuel and roundwood reached about 3300 (10 6 ) m 3 in 1999. About 55% is used directly as fuel, e.g. as split firewood, and about 90% of this is produced and consumed in the developing countries. The remaining 45% is used as industrial raw material, but about 40% of this is used as primary or secondary process residues, suitable only for energy production. The total sustainable worldwide biomass energy potential is about 100 EJ/a (the share of woody biomass is 41.6 EJ/a), which is about 30% of total global energy consumption today. About 40 EJ/a of available biomass is used for energy. Nearly 60% of this biomass is used only in Asia. A comparison between the available potential with current use shows that on a worldwide level about two-fifths of the existing biomass potential is used, and in most areas of the world the current biomass use is clearly below the available potential. Only in Asia does the current use exceed the available potential. Therefore, an increased biomass use is possible, e.g. for production of densified biofuels, in most countries.

Encyclopedia of Energy

Abstract: Basics of Energy Energy Flows Society and Energy History and Energy Systems of Energy Conservation and End Use Renewable and Alternative Sources Environmental Issues Public Issues Policy Issues Economics of Energy Measurement and Models Material Use and Reuse Oil and Natural Gas Coal, Electricity Nuclear Energy Risks Sustainable Development Global Issues Appendices.

Biomass fast pyrolysis

Abstract: Bioenergy is now accepted as having the potential to provide the major part of the projected renewable energy provisions of the future. Fast pyrolysis is one of the three main thermal routes, with gasification and combustion, to providing a useful and valuable biofuel. It is one of the most recent renewable energy processes to have been introduced and offers the advantages of a liquid product bio-oil that can be readily stored and trans ported, and used as a fuel, an energy carrier and a source of chemicals. Fast pyrolysis has now achieved commercial success for production of some chemicals, liquid fuel and electricity. Bio-oils have been success fully tested in engines turbines and boilers, and have been upgraded to high quality hydrocarbon fuels although at a presently unacceptable energetic and financial cost. This review concentrates on the technology of pyrolysis and applications for the liquid product. The basic pyrolysis process and the characteristics of the main liquid product bio-oil are first summarized followed by a review of applications for bio-oil. The main technical and non-technical barriers to implementation are identified.

Renewable Energy Policies and Barriers

Abstract: The 1990s saw an explosion of energy policy changes around the globe Driven by economic, environmental, security, and social concerns, energy regulation has been in great flux Many of the changes are having a profound influence on renewable energy, both from policies explicitly designed to promote renewable energy and from other policies that indirectly influence incentives and barriers for renewable energy This article considers six different types of policies that affect renewable energy development, both directly or indirectly: renewable energy promotion policies, transport biofuels policies, emissions reduction policies, electric power restructuring policies, distributed generation policies, and rural electrification policies Each policy reduces one or more key barriers that impede development of renewable energy These barriers are discussed first In general, most renewable energy policies address cost-related barriers in some manner Many policies address the requirements for utilities to purchase renewable energy from power producers Most policies also address the perceived risks of renewable energy in one form or another (ie, technical, financial, legal) Still others primarily address regulatory and institutional barriers Some related policies may heighten barriers to renewable energy rather than reduce them Table 1 summarizes the key renewable energy policies and barriers presented

Performance of a stand-alone renewable energy system based on energy storage as hydrogen

Abstract: Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energy (RE). A stand-alone RE system based on energy storage as hydrogen has been developed and installed at the Hydrogen Research Institute, and successfully tested for autonomous operation with developed control system and power conditioning devices. The excess energy produced, with respect to the load requirement, has been sent to the electrolyzer for hydrogen production. When energy produced from the RE sources became insufficient, with respect to the load requirement, the stored hydrogen was fed to a fuel cell to produce electricity. The RE system components have substantially different voltage-current characteristics and they are integrated through power conditioning devices on a dc bus for autonomous operation by using a developed control system. The developed control system has been successfully tested for autonomous operation and energy management of the system. The experimental results clearly indicate that a stand-alone RE system based on hydrogen production is safe and reliable.

Ethanol learning curve—the Brazilian experience

Abstract: Economic competitiveness is a very frequent argument against renewable energy (RE). This paper demonstrates, through the Brazilian experience with ethanol, that economies of scale and technological advances lead to increased competitiveness of this renewable alternative, reducing the gap with conventional fossil fuels.

Solar radiation and daylight models

Abstract: Preface Rapid sale of the first edition in a relatively short time plus the need to update information for an area of significant activity has dictated the need for the second edition of this book. Of late, the rapid deployment of solar photovoltaic technology across the globe has also demanded a need for the estimation of the local availability of the solar energy resource. In this respect the user will find that a considerable amount of new information, along with computational tools has been added in this edition. New material and, in most cases, resulting computer programs on the following topics has been provided: (a) Sun-path diagrams for abbreviated analysis. (b) New data files on measured data sets of irradiance and illuminance. (c) Distance between any two locations (solar radiation measurement site and location of its utilisation). (d) Characterisation of sky clarity indices and solar climate for any given location. (e) Corrections for sky-diffuse irradiance measurements using a shade-ring device. (f) Quality control of measured solar radiation and daylight data including outlier analysis. (g) Cloud radiation model. (h) Page radiation model (developed by Emeritus Professor John Page). (i) An extensive section on various forms of turbidity and their inter-relationships. (j) Newer generation of turbidity-based radiation models. (k) The European clear-sky solar radiation model (developed by Emeritus Professor John Page). (l) Procedures for obtaining sunshine data from cloud cover information and vice versa. (m) Frequency of occurrence of diffuse and global illuminance. (n) Zenith luminance models. (o) New all-sky CIE standard for sky luminance distribution. (p) Spectral radiation. (q) Detailed measured data sets of solar radiation and other meteorological parameters. (r) Web sites that provide solar radiation and daylight data and other related information. In response to a demand from readers and reviewers of this book a section on estimation of clear-sky solar irradiance for any part of the globe has been added. Within the past 5 years there has been an acceleration of activity in the exploitation of solar energy and this has primarily resulted from protection of environment pressures. The Kyoto protocol for reduction of carbon dioxide has been an important instrument in this respect. Subsidies offered for the use of solar water heating and building integrated photovoltaic installations (BIPV technology) within the European Union countries have resulted in a rapid take-off of these and related technologies. Another contributing factor that will eventually lead to the use of solar power within the transport sector is the spiralling monetary and environment costs associated with the current use of fossil fuels. With the rapid decline in the oil reserves within the Gulf of Mexico basin, Iraq has become the linchpin in the US strategy to secure cheap oil. Between Saudi Arabia and Iraq, with their respective proven oil reserves of 262 and 112 billion barrels, a staggering 40% of world’s oil reserves is shared. With the US invasion of Iraq it appears that a new phase of ‘Energy wars’ has started that may indeed spill over to other Opec countries. The repercussions of such actions and the fact that cheaper oil resulting from the ‘capture’ of oil reserves will lead to a faster consumption may indeed herald the true age of solar energy. In this respect world political leaders would be well advised to promote renewable energy technologies. That is the only and truly sustainable action for the abatement of the effects of an increase in atmospheric greenhouse gas loading.

On the global and regional potential of renewable energy sources

Abstract: In this thesis, the central research question is: what can be the contribution of renewable energy sources to the present and future world and regional energy supply system The focus is on wind, solar PV and biomass energy (energy crops) for electricity generation For the assessment of the economic potential, we construct cost-supply curves As the economic potential also depends on the way renewables are integrated in the electricity system, we also explore the overall costs of wind electricity with increasing penetration levels of the installed wind capacity into the system The potentials of solar, wind and biomass electricity are analysed at a global and regional level, for seventeen world-regions similar as used in the IMAGE 22 model to make future use of the results for scenario analysis with the IMAGE 22 model possible The IMAGE 22 model (Integrated Model to Assess the Global Environment) is developed at the National Institute of Public Health and the Environment (RIVM)) This model is one of those used for the construction and evaluation of SRES energy scenarios by the Intergovernmental Panel on Climate Change (IPCC) In summary, we can conclude that the renewable electricity sources studied in this thesis have a potential to generate several times more electricity than the present electricity demand at costs in the range of present electricity costs Solar PV has the most significant technical potential, but is at present not available at competitive costs in grid connected options In the longer term, costs of solar PV may come down at cost levels comparable to conventional electricity, especially in sunny areas The costs depend in the case of biomass electricity strongly on the technological development of the agricultural sector, on the labour wages, the capital-labour ratio and the land rental costs Costs of wind electricity are already nearly competitive and the wind electricity sector has increased considerably the last decades However, to what extent the overall costs of wind electricity can decrease further with increasing penetration levels, depends amongst others on the available storage capacity and interconnection of the system The spatially explicit calculations done in this study provide interesting new insights concerning the potential of renewable energy sources This thesis considers on a grid-cell level, next to climatic characteristics, also characteristics of land-use and soil quality, when estimating the future potential of renewables In particular for the assessment of the future potential of biomass energy, the demand for agricultural land is of high importance as these are expected to be planted at abandoned agricultural land Land area required to generate the wind electricity potential depends on social factors, but default values in this thesis indicate that to generate 6 times the present electricity production about 11 Gha is needed, about the size of China To generate about 23 times the present electricity production with solar PV, an area of 023 Gha is needed, about 20% of China To generate biomass derived electricity equal to 5 times the present electricity production, in the A1 scenario (highest potential) at abandoned agricultural area, about 13 Gha is needed, about 120% of the area of China

Solar Cells: Materials, Manufacture and Operation

Abstract: The capture and use of solar energy has been growing for many years, but only in recent times have advances in design and manufacture allowed us to see the incorporation of solar energy as a significant player in the renewable energy arena. Solar cells are at the heart of any photovoltaic system and in this book the various types are described and their characteristics reviewed. Going beyond materials, design and function, ?Solar Cells? also covers their testing, monitoring and calibration thus providing a comprehensive account of current activity in this important field of research and industry. 'Solar Cells' has been abstracted from the recent 'Practical Handbook of Photovoltaics' by the same editors

Geothermal (ground-source) heat pumps a world overview

Abstract: INTRODUCTION Geothermal (ground-source) heat pumps (GHP) are one of the fastest growing applications of renewable energy (see discussion at the end of this article) in the world, with annual increases of 10% in about 30 countries over the past 10 years. Its main advantage is that it uses normal ground or groundwater temperatures (between about 5 and 30C), which are available in all countries of the world. Most of this growth has occurred in the United States and Europe, though interest is developing in other countries such as Japan and Turkey. The present worldwide installed capacity is estimated at almost 12,000 MWt (thermal) and the annual energy use is about 72,000 TJ (20,000 GWh). The actual number of installed units is around 1,100,000, but the data are incomplete. Table 1 lists the countries with the highest use of GHPs.

System impact study for the interconnection of wind generation and utility system

Abstract: Following in the steps of the gas industry, the traditional paradigm of the vertically integrated electric utility structure has begun to change. In the United States, the Federal Energy Regulatory Commission (FERC) has issued several rules and Notices of Proposed Rulemaking (NOPR) to set the road map for the deregulated utility industry. The crisis in California has drawn great attention and sparked intense discussion within the utility industry. One general conclusion is to rejuvenate the idea of integrated resource planning and promote the distributed generation via traditional or renewable generation facilities for the deregulated utility systems. Wind generation is the most mature and cost effective resource among different renewable energy technologies. Recently, several large-scale wind generation projects have been implemented in the US and other parts of the world. Similar to other new generation facilities, the impacts of a large scale wind generation on the system operation, voltage profile, and system security have to be investigated and studied. Remedies for possible operation issues have to be evaluated and implemented. This paper discusses the impact study of connecting a 120 MW wind farm into the transmission system of a utility company within the Southwest Power Pool (SPP).

Increasing renewable energy sources in island energy supply : case study Porto Santo

Abstract: While the energy supply of most islands depends mainly on expensive oil derivatives’ importation, the others are linked by usually a weak electricity grid connection to the mainland. Due to high energy costs the islands are proving to be excellent test beds for the introduction of new technologies, and some islands are trying to become so-called renewable islands, to satisfy their energy demand mainly or entirely from indigenous and renewable sources, thus increasing the security of supply, and employment opportunities, without necessarily increasing the costs. Islands that have energy sources, such as hydro or geothermal energy, can easily integrate them into the power system, but those with mainly intermittent renewable energy sources are confronted with the necessity of energy storage. The most promising technologies are reversible hydro where geography allows, and storing hydrogen where it does not. The stored hydrogen can later be used for electricity production, and also for transport. This paper describes the H2RES model for optimisation of integration of hydrogen usage with intermittent renewable energy sources on the example of an isolated island in the Madeira archipelago, Porto Santo. It shows that it is possible to significantly increase the penetration of renewable energy sources, albeit at a relatively high cost, with hydrogen storage technology. The H2RES model, which includes reversible hydro and batteries as storage technologies, can serve as a valuable tool for island energy planning.

Wind Power: Renewable Energy for Home, Farm and Business

Abstract: In the wake of mass blackouts and energy crises, wind power remains a largely untapped resource of renewable energy. It is a booming worldwide industry whose technology, under the collective wing of aficionados like author Paul Gipe, is coming of age. Wind Power guides us through the emergent, sometimes daunting discourse on wind technology, giving frank explanations of how to use wind technology wisely and sound advice on how to avoid common mistakes. Since the mid-1970s, Paul Gipe has played a part in nearly every aspect of wind energy's development--from installing small turbines to promoting wind energy worldwide. As an American proponent of renewable energy, Gipe has earned the acclaim and respect of European energy specialists for years, but his arguments have often fallen on deaf ears at home. Today, the topic of wind power is cropping up everywhere from the beaches of Cape Cod to the Oregon-Washington border, and one wind turbine is capable of producing enough electricity per year to run 200 average American households. Now, Paul Gipe is back to shed light on this increasingly important energy source with a revised edition of Wind Power. Over the course of his career, Paul Gipe has been a proponent, participant, observer, and critic of the wind industry. His experience with wind has given rise to two previous books on the subject, Wind Energy Basics and Wind Power for Home and Business, which have sold over 50,000 copies. Wind Power for Home and Business has become a staple for both homeowners and professionals interested in the subject, and now, with energy prices soaring, interest in wind power is hitting an all-time high. With chapters on output and economics, Wind Power discloses how much you can expect from each method of wind technology, both in terms of energy and financial savings. The book's updated models, graphics, and weighty appendixes make it an invaluable reference for everyone interested in the emerging trend of wind power and renewable energy. Executive Director of the American Wind Energy Association Randall Swisher has said, "In the last two decades, no one has done more that Paul Gipe to bring wind energy to the public's attention."