Showing papers on "Renewable energy published in 2003"

Energy Resources and Global Development

Abstract: In order to address the economic and environmental consequences of our global energy system, we consider the availability and consumption of energy resources. Problems arise from our dependence on combustible fuels, the environmental risks associated with their extraction, and the environmental damage caused by their emissions. Yet no primary energy source, be it renewable or nonrenewable, is free of environmental or economic limitations. As developed and developing economies continue to grow, conversion to and adoption of environmentally benign energy technology will depend on political and economic realities.

Ethanol Fuels: Energy Balance, Economics, and Environmental Impacts are Negative

Abstract: Several studies suggest that the $1.4 billion in government subsidies are encouraging the ethanol program without substantial benefits to the U.S. economy. Large ethanol industries and a few U.S. government agencies, such as the USDA, support the production of ethanol. Corn-farmers receive minimal profits. In the U.S. ethanol system, considerably more energy, including high-grade fossil fuel, is required to produce ethanol than is available in the energy-ethanol output. Specifically about 29% more energy is used to produce a gallon of ethanol than the energy in a gallon of ethanol. Fossil energy powers corn production and the fermentation/distillation processes. Increasing subsidized ethanol production will take more feed from livestock production, and is estimated to currently cost consumers an additional $1 billion per year. Ethanol production increases environmental degradation. Corn production causes more total soil erosion than any other crop. Also, corn production uses more insecticides, herbicides, and nitrogen fertilizers than any other crop. All these factors degrade the agricultural and natural environment and contribute to water pollution and air pollution. Increasing the cost of food and diverting human food resources to the costly inefficient production of ethanol fuel raise major ethical questions. These occur at a time when more than half of the world's population is malnourished. The ethical priority for corn and other food crops should be for food and feed. Subsidized ethanol produced from U.S. corn is not a renewable energy source.

Renewable energy markets in developing countries

Abstract: ▪ Abstract Renewable energy is shifting from the fringe to the mainstream of sustainable development. Past donor efforts achieved modest results but often were not sustained or replicated, which leads now to greater market orientation. Markets for rural household lighting with solar home systems, biogas, and small hydro power have expanded through rural entrepreneurship, government programs, and donor assistance, serving millions of households. Applications in agriculture, small industry, and social services are emerging. Public programs resulted in 220 million improved biomass cook stoves. Three percent of power generation capacity is largely small hydro and biomass power, with rapid growth of wind power. Experience suggests the need for technical know-how transfer, new replicable business models, credit for rural households and entrepreneurs, regulatory frameworks and financing for private power developers, market facilitation organizations, donor assistance aimed at expanding sustainable markets, smart...

Foundations for offshore wind turbines

Abstract: An important engineering challenge of today, and a vital one for the future, is to develop and harvest alternative sources of energy. This is a firm priority in the UK, with the government setting ...

A regional energy planning methodology including renewable energy sources and environmental constraints

Abstract: In this paper, a bottom-up energy system optimisation model is proposed in order to support planning policies for promoting the use of renewable energy sources. A linear programming optimisation methodology based on the energy flow optimisation model (EFOM) is adopted, detailing the primary energy sources exploitation (including biomass, solid waste, process by-products), power and heat generation, emissions and end-use sectors. The modelling framework is enhanced in order to adapt the model to the characteristics and requirements of the region under investigation. In particular, a detailed description of the industrial cogeneration system, that turns out to be the more efficient and increasingly spread, is incorporated in the regional model. The optimisation process, aiming to reduce environmental impact and economical efforts, provides feasible generation settlements that take into account the installation of combined cycle power plants, wind power, solid-waste and biomass exploitation together with industrial combined heat and power (CHP) systems. The proposed methodology is applied to case of the Apulia region in the Southern Italy.

Modern Control Design for Flexible Wind Turbines

Abstract: Control can improve energy capture and reduce dynamic loads in wind turbines. In the 1970s and 1980s, wind turbines used classical control designs to regulate power and speed. The methods used, however, were not always successful. Modern turbines are larger, mounted on taller towers, and more dynamically active than their predecessors. Control systems to regulate turbine power and maintain stable, closed-loop behavior in the presence of turbulent wind inflow will be critical for these designs. This report applies modern state-space control design methods to a two-bladed teetering hub upwind machine at the National Wind Technology Center (NWTC), which is managed by the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) in Golden, Colorado. The design objective is to regulate turbine speed and enhance damping in several low-damped flexible modes of the turbine. Starting with simple control algorithms based on linear models, complexity is added incrementally until the desired performance is firmly established.

A review on the energy production, consumption, and prospect of renewable energy in China

Abstract: China is the second largest energy consumer in the world This paper reviews the production and consumption of traditional and renewable energy in China over the past three decades It also presents an overview on the research and development of renewable energy, such as solar, biomass, geothermal, ocean and wind energy in China Study indicated that the usage of renewable energy in China shows a promising prospect in the near future, of which biomass is found to be one of the most promising renewable energy resources that have great potential for development in China

High efficiency generation of hydrogen fuels using nuclear power

Abstract: OAK B202 HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER. Combustion of fossil fuels, used to power transportation, generate electricity, heat homes and fuel industry provides 86% of the world's energy. Drawbacks to fossil fuel utilization include limited supply, pollution, and carbon dioxide emissions. Carbon dioxide emissions, thought to be responsible for global warming, are now the subject of international treaties. Together, these drawbacks argue for the replacement of fossil fuels with a less-polluting potentially renewable primary energy such as nuclear energy. Conventional nuclear plants readily generate electric power but fossil fuels are firmly entrenched in the transportation sector. Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. Hydrogen will be particularly advantageous when coupled with fuel cells. Fuel cells have higher efficiency than conventional battery/internal combustion engine combinations and do not produce nitrogen oxides during low-temperature operation. Contemporary hydrogen production is primarily based on fossil fuels and most specifically on natural gas. When hydrogen is produced using energy derived from fossil fuels, there is little or no environmental advantage. There is currently no large scale, cost-effective, environmentally attractive hydrogen production process available for commercialization, nor has such a process been identified. The objective of this work is to find an economically feasible process for the production of hydrogen, by nuclear means, using an advanced high-temperature nuclear reactor as the primary energy source. Hydrogen production by thermochemical water-splitting (Appendix A), a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or, in the case of a hybrid thermochemical process, by a combination of heat and electrolysis, could meet these goals. Hydrogen produced from fossil fuels has trace contaminants (primarily carbon monoxide) that are detrimental to precious metal catalyzed fuel cells, as is now recognized by many of the world's largest automobile companies. Thermochemical hydrogen will not contain carbon monoxide as an impurity at any level. Electrolysis, the alternative process for producing hydrogen using nuclear energy, suffers from thermodynamic inefficiencies in both the production of electricity and in electrolytic parts of the process. The efficiency of electrolysis (electricity to hydrogen) is currently about 80%. Electric power generation efficiency would have to exceed 65% (thermal to electrical) for the combined efficiency to exceed the 52% (thermal to hydrogen) calculated for one thermochemical cycle. Thermochemical water-splitting cycles have been studied, at various levels of effort, for the past 35 years. They were extensively studied in the late 70s and early 80s but have received little attention in the past 10 years, particularly in the U.S. While there is no question about the technical feasibility and the potential for high efficiency, cycles with proven low cost and high efficiency have yet to be developed commercially. Over 100 cycles have been proposed, but substantial research has been executed on only a few. This report describes work accomplished during a three-year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first phase was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most three) for further detailed consideration. During Phase 1, an exhaustive literature search was performed to locate all cycles previously proposed. The cycles located were screened using objective criteria to determine which could benefit, in terms of efficiency and cost, from the high-temperature capabilities of advanced nuclear reactors. The more promising cycles were then analyzed in depth as to their adaptability to advanced high-temperature nuclear reactors. As a result, the Sulfur-Iodine (S-I) cycle was selected for integration into the advanced nuclear reactor system. In Phases 2 and 3, alternative flowsheets were developed and compared. This effort entailed a considerable effort into developing the solution thermodynamics pertinent to the S-I cycle.

Gas-Fired Distributed Energy Resource Technology Characterizations

Abstract: The U. S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) is directing substantial programs in the development and encouragement of new energy technologies. Among them are renewable energy and distributed energy resource technologies. As part of its ongoing effort to document the status and potential of these technologies, DOE EERE directed the National Renewable Energy Laboratory to lead an effort to develop and publish Distributed Energy Technology Characterizations (TCs) that would provide both the department and energy community with a consistent and objective set of cost and performance data in prospective electric-power generation applications in the United States. Toward that goal, DOE/EERE - joined by the Electric Power Research Institute (EPRI) - published the Renewable Energy Technology Characterizations in December 1997.As a follow-up, DOE EERE - joined by the Gas Research Institute - is now publishing this document, Gas-Fired Distributed Energy Resource Technology Characterizations.

The renewable energy response to climate change

Abstract: The environmental impacts from fossil fuel use particularly climate change, security of future energy supplies and energy poverty, are the key drivers for further development and deployment of renewable energy technologies and distributed energy systems. High capital investment is required to achieve this, though this would be partly offset by savings in the cost of constructing new large power stations and the infrastructure necessary to transmit gas and electricity over large distances. Many proposed renewable energy projects have relatively low investment costs in terms of $/tonne of carbon avoided but the development of further policies and mechanisms by governments is required to enable renewables to compete more fairly with traditional fossil fuels and nuclear power, often carrying high subsidies in various forms. Valuing the cost of emitting carbon into the atmosphere is one such approach. Recent developments resulting in improvements in performance and the lowering of costs of renewable energy technologies and systems has led to their rapid growth, particularly of wind and solar. However many scenarios of future global energy use still show them providing less than 4% of the world's primary energy supply by 2030. If mitigation of climate change is to prove successful and occur in time to minimize the costs of adaptation, then a more rapid uptake of renewable energy will be required. Greater investment now to drive the cost of renewables further down their experience curves will lead to less risk from climate change and lower investment costs in the longer term.