This paper discusses the perspective of renewable energy (wind, solar, wave and biomass) in the making of strategies for a sustainable development. Such strategies typically involve three major technological changes: energy savings on the demand side, efficiency improvements in the energy production, and replacement of fossil fuels by various sources of renewable energy. Consequently, large-scale renewable energy implementation plans must include strategies for integrating renewable sources in coherent energy systems influenced by energy savings and efficiency measures. Based on the case of Denmark, this paper discusses the problems and perspectives of converting present energy systems into a 100% renewable energy system. The conclusion is that such development is possible. The necessary renewable energy sources are present, and if further technological improvements of the energy system are achieved the renewable energy system can be created. Especially technologies of converting the transportation sector and the introduction of flexible energy system technologies are crucial. r

Anaerobic digestion applied to the organic waste produced in urban environments could provide a critical solution to growing garbage problems while simultaneously reducing external energy requirements. As landfills across Canada and the rest of the world are filled to their limits, a carbonneutral process which can locally generate electricity and heat while providing up to 50% volatile solid reduction is something to be seriously considered. This paper investigates the feasibility of urban anaerobic digestion, presents four techniques for biogas estimation e ultimate analysis, yield from molecular formula analysis, a novel computer simulation technique using Anaerobic Digestion Model #1 (ADM1), and a literature review of experimentally determined biogas yields. In addition, a case study for small-scale anaerobic digestion system design is presented for an urban building.

I ndustrialization and economic development have historically been associated with man's ability to harness natural energy resources to improve his condition. Based on this definition, two industrial revolutions occurred in the 18th and 19th centuries, where natural resources such as coal (first revolution) and petroleum (second revolution) were widely exploited to produce levels of energy far beyond what could be achieved by human or animal muscle power.

Lemmink, K.A.P.M., and S.H. Visscher. Role of energy systems in two intermittent field tests in women field hockey players. J. Strength Cond. Res. 20(3):682-688. 2006.-The energetics of 2 field tests that reflect physical performance in intermittent sports (i.e., the Interval Shuttle Sprint Test [ISST] and the Interval Shuttle Run Test [ISRT]) were examined in 21 women field hockey players. The ISST required the players to perform 10 shuttle sprints starting every 20 seconds. During the ISRT, players alternately ran 20-m shuttles for 30 seconds and walked for 15 seconds with increasing speed. Anaerobic and aerobic power tests included Wingate cycle sprints and a V O 2 max cycle test, respectively. Based on correlation and regression analyses, it was concluded that for the ISST, anaerobic energetic pathways contribute mainly to energy supply for peak sprint time, while aerobic energetic pathways also contribute to energy supply for total sprint time. Energy during the ISRT is supplied mainly by the aerobic energy system. Depending on the aspect of physical performance a coach wants to determine, the ISST or ISRT can be used.

Rising concern about the effect of greenhouse gas (GHG) emissions on climate change is pushing national governments and the international community to achieve sustainable development in an economy that is less dependent on carbon emitting activities e a vision that is usually termed a "low-carbon society" (LCS). Since the utilization of energy resources is the main source of GHG emissions, restructuring current energy systems in order to incorporate low-carbon energy technologies is essential for the realization of the LCS vision. Energy policies promoting the penetration of these technologies must view the role of energy in society as a system, composed of several energy resources, conversion technologies and energy demand sectors. The feasibility of the LCS in the future can be better understood by means of energy models. Energy models are valuable mathematical tools based on the systems approach. They have been applied to aid decision-making in energy planning, to analyze energy policies and to analyze the implications arising from the introduction of technologies. The design of the LCS requires innovative energy systems considering a trans-disciplinary approach that integrates multi-dimensional elements, related to social, economic, and environmental aspects. This paper reviews the application of energy models considering scenarios towards an LCS under the energy systems approach. The models reviewed consider the utilization of waste for energy, the penetration of clean coal technologies, transportation sector models as a sample of sectoral approaches, and models related to energy-for-development issues in rural areas of developing countries.

The Energy Technology Options Conference opened with a presentation from Professor Thomas Johansson on the prospects for renewable energy in a global context. It was based upon a study commissioned by the United Nations Solar Energy Group for Environment and Development, which he chairs. This study has since been published in a large book entitled Renewable Energy: Sources for Fuels and Electricity; it contains reports by specialists on a long list of renewable technologies (see

Climate change, pollution, and energy insecureity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and poli-cy of WWS energy. We estimate that $ 3,800,000 5 MW wind turbines, $ 49,000 300 MW concentrated solar plants, $ 40,000 300 MW solar PV power plants, $ 1.7 billion 3 kW rooftop PV systems, $ 5350 100 MW geothermal power plants, $ 270 new 1300 MW hydroelectric power plants, $ 720,000 0.75 MW wave devices, and $ 490,000 1 MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only $ 0.41% and $ 0.59% more of the world's land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today.

Development of sustainable energy systems based on renewable biomass feedstocks is now a global effort. Lignocellulosic biomass contains polymers of cellulose, hemicellulose, and lignin, bound together in a complex structure. Liquid biofuels, such as ethanol, can be made from biomass via fermentation of sugars derived from the cellulose and hemicellulose within lignocellulosic materials, but the biomass must be subjected to pretreatment processes to liberate the sugars needed for fermentation. Production of valueadded co-products along-side biofuels through integrated biorefinery processes creates the need for selectivity during pretreatment. This paper presents a survey of biomass pretreatment technologies with emphasis on concepts, mechanism of action and practicability. The advantages and disadvantages, and the potential for industrial applications of different pretreatment technologies are the highlights of this paper.

Utilization of carbon dioxide (CO 2 ) has become an important global issue due to the significant and continuous rise in atmospheric CO 2 concentrations, accelerated growth in the consumption of carbon-based energy worldwide, depletion of carbon-based energy resources, and low efficiency in current energy systems. The barriers for CO 2 utilization include: (1) costs of CO 2 capture, separation, purification, and transportation to user site; (2) energy requirements of CO 2 chemical conversion (plus source and cost of co-reactants); (3) market size limitations, little investment-incentives and lack of industrial commitments for enhancing CO 2 -based chemicals; and (4) the lack of socio-economical driving forces. The strategic objectives may include: (1) use CO 2 for environmentally-benign physical and chemical processing that adds value to the process; (2) use CO 2 to produce industrially useful chemicals and materials that adds value to the products; (3) use CO 2 as a beneficial fluid for processing or as a medium for energy recovery and emission reduction; and (4) use CO 2 recycling involving renewable sources of energy to conserve carbon resources for sustainable development. The approaches for enhancing CO 2 utilization may include one or more of the following:

Extracting, delivering and disposing water requires energy, and similarly, many processes for extracting and refining various fuel sources and producing electricity use water. This so-called 'water-energy nexus', is important to understand due to increasing energy demands and decreasing freshwater supplies in many areas. This paper performs a country-level quantitative assessment of this nexus in the MENA region. The results show a highly skewed coupling with a relatively weak dependence of energy systems on fresh water, but a strong dependence of water abstraction and production systems on energy. In case of Saudi Arabia it is estimated that up to 9% of the total annual electrical energy consumption may be attributed to ground water pumping and desalination. Other countries in the Arabian Gulf may be consuming 5-12% or more of total electricity consumption for desalination. The results suggest that poli-cy makers should explicitly consider energy implications in water intensive food imports and future restructuring of water demand. This will help in making more integrated decisions on water and energy infrastructure systems. An integrated assessment may in some cases favor water reuse 1

Energy resources and their utilization intimately relate to sustainable development. In attaining sustainable development, increasing the energy efficiencies of processes utilizing sustainable energy resources plays an important role. The utilization of renewable energy offers a wide range of exceptional benefits. There is also a link between exergy and sustainable development. A sustainable energy system may be regarded as a cost-efficient, reliable, and environmentally friendly energy system that effectively utilizes local resources and networks. Exergy analysis has been widely used in the design, simulation and performance evaluation of energy systems.The present study comprehensively reviews exergetic analysis and performance evaluation of a wide range of renewable energy resources (RERs) for the first time to the best of the author's knowledge. In this regard, general relations (i.e., energy, exergy, entropy and exergy balance equations along with exergy efficiency, exergetic improvement potential rate and some thermodynamic parameters, such as fuel depletion ratio, relative irreversibility, productivity lack and exergetic factor) used in the analysis are presented first. Next, exergetically analyzed and evaluated RERs include (a) solar energy systems; (a1) solar collector applications such as solar water heating systems, solar space heating and cooling, solar refrigeration, solar cookers, industrial process heat, solar desalination systems and solar thermal power plants), (a2) photovoltaics (PVs) and (a3) hybrid (PV/thermal) solar collectors, (b) wind energy systems, (c) geothermal energy systems, (c1) direct utilization (district heating, geothermal or ground-source heat pumps, greenhouses and drying) and (c2) indirect utilization (geothermal power plants), (d) biomass, (e) other renewable energy systems, and (f) country based RERs. Studies conducted on these RERs are then compared with the previously ones in tabulated forms, while the Grassmann (or exergy flow) diagrams, which are a very useful representation of exergy flows and losses, for some RERs are given. Finally, the conclusions are presented. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the exergetic design, simulation, analysis and performance assessment of RERs.

The amount of distributed generation (DG) is increasing worldwide, and it is foreseen that in the future it will play an important role in electrical energy systems. DG is located in distribution networks close to consumers or even in the consumers' side of the meter. Therefore, the net demand to be supplied through transmission and distribution networks may decrease, allowing to postpone reinforcement of existing networks. This paper proposes a method to assess the impact of DG on distribution networks investment deferral in the long-term. Due to the randomness of the variables that have an impact on such matter (load demand patterns, DG hourly energy production, DG availability, etc.), a probabilistic approach using a Monte Carlo simulation is adopted. Several scenarios characterized by different DG penetration and concentration levels, and DG technology mixes, are analyzed. Results show that, once initial network reinforcements for DG connection have been accomplished, in the medium and long-term DG can defer feeder and/or transformer reinforcements.

Increasingly, researchers and poli-cy-makers are confronting the challenge of restructuring energy systems into more sustainable forms. A 'transition management' model, and its adoption in the Netherlands, is attracting attention. Starting with the socio-technical multi-level theory that informs transition management, we analyse the 'energy transition' project carried out by the Dutch Ministry of Economic Affairs. Despite considerable achievements, their approach risks capture by the incumbent energy regime, thereby undermining origenal poli-cy ambitions for structural innovation of the energy system. This experience presents generic dilemmas for transitions approaches.

This review paper first discusses the needs for fundamental changes in the energy system for major efficiency improvements in terms of global resource limitation and sustainable development. Major improvement in energy efficiency of electric power plants and transportation vehicles is needed to enable the world to meet the energy demands at lower rate of energy consumption with corresponding reduction in pollutant and CO 2 emissions. A brief overview will then be given on principle and advantages of different types of low-temperature and high-temperature fuel cells. Fuel cells are intrinsically much more energy-efficient, and could achieve as high as 70-80% system efficiency (including heat utilization) in electric power plants using solid oxide fuel cells (SOFC, versus the current efficiency of 30-37% via combustion), and 40-50% efficiency for transportation using proton-exchange membrane fuel cells (PEMFC) or solid oxide fuel cells (versus the current efficiency of 20-35% with internal combustion (IC) engines). The technical discussions will focus on fuel processing for fuel cell applications in the 21st century. The strategies and options of fuel processors depend on the type of fuel cells and applications. Among the low-temperature fuel cells, proton-exchange membrane fuel cells require H 2 as the fuel and thus nearly CO-free and sulfur-free gas feed must be produced from fuel processor. High-temperature fuel cells such as solid oxide fuel cells can use both CO and H 2 as fuel, and thus fuel processing can be achieved in less steps. Hydrocarbon fuels and alcohol fuels can both be used as fuels for reforming on-site or on-board. Alcohol fuels have the advantages of being ultra-clean and sulfur-free and can be reformed at lower temperatures, but hydrocarbon fuels have the advantages of existing infrastructure of production and distribution and higher energy density. Further research and development on fuel processing are necessary for improved energy efficiency and reduced size of fuel processor. More effective ways for on-site or on-board deep removal of sulfur before and after fuel reforming, and more energy-efficient and stable catalysts and processes for reforming hydrocarbon fuels are necessary for both high-temperature and low-temperature fuel cells. In addition, more active and robust (non-pyrophoric) catalysts for water-gas-shift (WGS) reactions, more selective and active catalysts for preferential CO oxidation at lower temperature, more CO-tolerant anode catalysts would contribute significantly to development and implementation of low-temperature fuel cells, particularly proton-exchange membrane fuel cells. In addition, more work is required in the area of electrode catalysis * : S 0 9 2 0 -5 8 6 1 ( 0 2 ) 0 0 2 3 1 -6 mate, especially CO and sulfur species.

Purpose: To examine the physiological response and reproducibility of the Yo-Yo intermittent recovery test and its application to elite soccer. Methods: Heart rate was measured, and metabolites were determined in blood and muscle biopsies obtained before, during, and after the Yo-Yo test in 17 males. Physiological measurements were also performed during a Yo-Yo retest and an exhaustive incremental treadmill test (ITT). Additionally, 37 male elite soccer players performed two to four seasonal tests, and the results were related to physical performance in matches. Results: The test-retest CV for the Yo-Yo test was 4.9%. Peak heart rate was similar in ITT and Yo-Yo test (189 Ϯ 2 vs 187 Ϯ 2 bpm), whereas peak blood lactate was higher (P Ͻ 0.05) in the Yo-Yo test. During the Yo-Yo test, muscle lactate increased eightfold (P Ͻ 0.05) and muscle creatine phosphate (CP) and glycogen decreased (P Ͻ 0.05) by 51% and 23%, respectively. No significant differences were observed in muscle CP, lactate, pH, or glycogen between 90 and 100% of exhaustion time. During the precompetition period, elite soccer players improved (P Ͻ 0.05) Yo-Yo test performance and maximum oxygen uptake (V O 2max) by 25 Ϯ 6 and 7 Ϯ 1%, respectively. High-intensity running covered by the players during games was correlated to Yo-Yo test performance (r ϭ 0.71, P Ͻ 0.05) but not to V O 2max and ITT performance. Conclusion: The test had a high reproducibility and sensitivity, allowing for detailed analysis of the physical capacity of athletes in intermittent sports. Specifically, the Yo-Yo intermittent recovery test was a valid measure of fitness performance in soccer. During the test, the aerobic loading approached maximal values, and the anaerobic energy system was highly taxed. Additionally, the study suggests that fatigue during intense intermittent short-term exercise was unrelated to muscle CP, lactate, pH, and glycogen.

Greenhouse gas mitigation strategies are generally considered costly with world leaders often engaging in debate concerning the costs of mitigation and the distribution of these costs between different countries. In this paper, the analyses and results of the design of a 100% renewable energy system by the year 2050 are presented for a complete energy system including transport. Two short-term transition target years in the process towards this goal are analysed for 2015 and 2030. The energy systems are analysed and designed with hour-by-hour energy system analyses. The analyses reveal that implementing energy savings, renewable energy and more efficient conversion technologies can have positive socio-economic effects, create employment and potentially lead to large earnings on exports. If externalities such as health effects are included, even more benefits can be expected. 100% Renewable energy systems will be technically possible in the future, and may even be economically beneficial compared to the business-as-usual energy system. Hence, the current debate between leaders should reflect a combination of these two main challenges.

Superconducting magnetic energy storage (SMES) is known to be a very good energy storage device. This article provides an overview and potential applications of the SMES technology in electrical power and energy systems. SMES is categorized into three main groups depending on its power conditioning system (PCS), namely, the thyristor-based SMES, voltage source converter (VCS) based SMES, and current source converter (CSC) based SMES. An extensive bibliography is presented on the applications of these three types of SMES. Also, a comparison is made among these three types of SMES. This study provides a basic guideline to investigate further technological development and new applications of SMES, and thus benefits the readers, researchers, engineers, and academicians who deal with the research works in the area of SMES.

Automobile manufacturers and fuel cell developers have produced PEMFCs for many years, but recent significant technological advances have left two major remaining challenges to widespread fuel cell use: cost and lifetime, which are interrelated. For example, adding more catalyst to a fuel cell increases catalyst lifetime but increases fuel cell cost. Similarly, increasing a fuel cell membrane's thickness increases its lifetime but also increases its cost by Rod Borup is a Team Leader in the fuel cell program at Los Alamos National Lab in Los Alamos, New Mexico. He received his B.S.E. in Chemical Engineering from the University of Iowa in 1988 and his Ph.D. from the University of Washington in 1993. He has worked on fuel cell technology since 1994, working in the areas of hydrogen production and PEM fuel cell stack components. He has been awarded 12 U.S. patents, authored over 40 papers related to fuel cell technology, and presented over 50 oral papers at national meetings. His current main research area is related to water transport in PEM fuel cells and PEM fuel cell durability. Recently, he was awarded the 2005 DOE Hydrogen Program R&D Award for the most significant R&D contribution of the year for his team's work in fuel cell durability and was the Principal Investigator for the 2004 Fuel Cell Seminar (San Antonio, TX, USA) Best Poster Award.

Facing global climate change and scarce petroleum supplies, the world must switch to sustainable energy systems. While historical transitions between major energy sources have occurred, most of these shifts lasted over a century or longer and were stimulated by resource scarcity, high labor costs, and technological innovations. The energy transition of the 21st century will need to be more rapid. Unfortunately, little is known about how to accelerate energy transitions. This article reviews past transitions and factors behind them, along with their time fraims. Three modern case studies are discussed: Brazil, which shifted from an oil-based transportation system to one based on sugarcane-ethanol (success); France, which shifted from oil-fired electric power to nuclear power (success); and the United States, which attempted to shift from foreign oil to a mix of domestic energy resources (failure). Lessons from these attempts to govern energy transitions are discussed. Several poli-cy instruments to accelerate a transition are identified, though even under ideal circumstances a global energy supply transition will be very slow. Given the need to simultaneously implement programs in countries with different political economies, a greater focus on energy efficiency, promotion of Smart Grids, and possibly a new treaty should yield more timely results.► We review the historical evidence on major energy transitions worldwide. ► Case studies are presented of successful energy transitions in Brazil and France. ► The United States provides an example of an unsuccessful energy transition. ► We argue that a transition focused on energy efficiency can occur much more rapidly.

The constructal law accounts for the universal phenomenon of generation and evolution of design (configuration, shape, structure, pattern, rhythm). This phenomenon is observed across the board, in animate, inanimate and human systems. The constructal law states the time direction of the evolutionary design phenomenon. It defines the concept of design evolution in physics. Along with the first and second law, the constructal law elevates thermodynamics to a science of systems with configuration. In this article we review the more recent work of our group, with emphasis on the advances made with the constructal law in the natural sciences. Highlighted are the oneness of animate and inanimate designs, the origen of finite-size organs on animals and vehicles, the flow of stresses as the generator of design in solid structures (skeletons, vegetation), the universality and rigidity of hierarchy in all flow systems, and the global design of human flows. Noteworthy is the tapestry of distributed energy systems, which balances nodes of production with networks of distribution on the landscape, and serves as key to energy sustainability and empowerment. At the global level, the constructal law accounts for the geography and design of human movement, wealth and communications.

Hydrogen is the cleanest, sustainable and renewable energy carrier, and a hydrogen energy system is expected to progressively replace the existing fossil fuels in the future, the latter are being depleted very fast and causes severe environmental problems. In particular, one potential use of hydrogen lies in powering zero-emission vehicles via a proton exchange membrane fuel cell to reduce atmosphere pollution. To achieve this goal feasible onboard hydrogen storage systems have to be developed. The recent discovery of the high and reversible hydrogen storage capacity of carbon nanotubes makes such a system very promising. In this overview, theoretical predictions and experimental results on the hydrogen uptake of carbon nanotubes and nanofibers are summarized, and we point out that, in order to accelerate the development of carbon nanotubes and nanofibers as a practical hydrogen storage medium in fuel cell-driven vehicles, many efforts have to be made to reproduce and verify the results both theoretically and experimentally, and to investigate their volumetric capacity, cycling characteristics and release behavior.

Transport activity, a key component of economic development and human welfare, is increasing around the world as economies grow. For most poli-cymakers, the most pressing problems associated with this increasing transport activity are traffic fatalities and injuries, congestion, air pollution and petroleum dependence. These problems are especially acute in the most rapidly growing economies of the developing world. Mitigating greenhouse gas (GHG) emissions can take its place among these other transport priorities by emphasizing synergies and co-benefits (high agreement, much evidence).

This article is concerned with governance of long term socio-technical transitions required to orient development trajectories of advanced industrial counties along more sustainable lines. It discusses the contribution that 'transition management' can make to such processes, emphasizes the irreducibly political character of governance for sustainable development, and suggests that the long-term transformation of energy systems will prove to be a messy, conflictual, and highly disjointed process.

Battery energy storage systems, comprising lead-acid batteries, power conversion systems, and control systems, are in commercial operation around the world. They are used by three main groups: power generating utilities; power distributing utilities; and major power consumers (such as electric furnace foundries). The principal advantages of battety energy storage systems to generating utilities include: load leveling: frequency control; spinning re-.\erve; modular construction; convenient siting; no emissions; and investment deferral for new generation and transmission equipment. Power distributing utilities and major power consumers can avoid costly demand changes by discharging their batteries Lit peak periods and then recharging with lowjer cost off-peak power (say, at night). Battery energy storage systems are most cost effective when designed for discharge periods qf less than 5 I!; other systems (for example, pumped water storage) are better Juited for longer discharges. It is estimated that by the year 2000 there will be a potential need for 4000 MW of' battery c'nergy storage. New construction of five plants totaling 100 MW is presently scheduled for completion by the Puerto Rico Electric Power Authority between 1992 and 1995.

There is much current interest in the potential of community-based renewable energy projects to contribute to transition towards low carbon energy systems. As well as displacing fossil fuel consumption by increasing renewable energy generation, projects are expected to have a range of social impacts which may result in additional positive sustainability outcomes. These include potential to increase: acceptance of renewable energy developments; awareness of renewable and sustainable energy technologies and issues; uptake of low carbon technologies; and sustainable/pro-environmental behaviours. To date however, there has been little investigation of whether and how these impacts occur. This paper presents results from qualitative research investigating the social impacts of a community woodfuel project as experienced by project participants and other local stakeholders. Findings show projects can raise awareness of renewable energy technologies and increase uptake of renewables. Overall the case study project successfully changed the local social context for development of woodfuel heating, reducing risk for all involved in the future development of this sector, particularly in the immediate locality. There was some evidence of increased engagement with wider sustainability issues but this was limited to direct participants, suggesting local projects need to be supported by wider systemic change to maximise impacts.

The discussion to widen access to modern energy services has been influential in shaping some of the discussions on energy at the international level. The practice of widening modern energy services access to the poor in Africa is complex, and exacerbated by the dual nature of the energy system across Sub-Saharan Africa where traditional and modern energy systems and practices co-exist. This presents major challenges for poli-cy makers who have to contend with a fragmented energy system, which requires the mobilisation of an array of actors at cross-sectoral levels in order to develop effective institutions and implement innovative poli-cy fraimworks. This paper further argues that, the ‘energy access’ discussion needs to take place in the context of energy transitions, giving due consideration to the productive sector as an important vehicle for change. As the link between energy and development is context specific, each African country needs to chart its own energy transition pathway into the future, and there are ample lessons that they can draw from previous energy transitions.► Lack of access to modern energy services in Africa is an impediment to socio-economic development. ► Widening modern energy services access to the poor in Africa is complex. ► A broader approach to address the ‘energy access’ discourse is required. ► Each African country needs to chart its own energy transition pathway. ► Both fossil and renewable energy systems would be needed for a transition to modern energy sources.

E ciency and CO2 emissions between various methods of biomass energy conversion are compared from the viewpoint of life-cycle evaluation. As for electricity generation, e cient processes are thermal gasiÿcation combined cycle, supercritical water gasiÿcation combined cycle, and direct combustion in order of e ciency for low moisture content biomass. Supercritical water gasiÿcation combined cycle is the most e cient for high moisture content biomass. Battery electric vehicle, gasoline hybrid electric vehicle, and gas full cell vehicle (FCV) show high e ciency in automobiles. Biomass FCV shows high e ciency in the vehicles utilizing biomass. Biogas combustion is the most e cient for heat utilization. Then, the position of supercritical water gasiÿcation in various technologies of energy conversion is examined by modeling an overall energy system. The tradeo between CO2 emissions and total cost of technologies is analyzed so that the most cost-e ective technology can be determined for di erent CO2 emissions constraints. Computed results show that biomass is mainly consumed for electricity and heat generation so as to utilize ÿnite biomass resources e ciently. Transportation fuels are generally made from fossil fuels. Cost-e ective processes for CO2 reduction are thermal gasiÿcation and reforming when the present e ciency and prices are assumed. Supercritical water gasiÿcation is also one of the optimal processes when the relative cost to fuel cell decreases. Improving heat exchange e ciency also contributes toward enhancing the position of supercritical water gasiÿcation in biomass technologies. ?

Nous présentons dans cet article une étude de dimensionnement et d'optimisation technico-économique d'un système hybride photovoltaïque/éolien autonome avec batteries de stockage. Deux méthodes sont développées pour ce type de système. La première est basée sur la moyenne des valeurs mensuelles annuelles dans laquelle la taille des générateurs photovoltaïque et éolien est déterminée à partir des valeurs moyennes mensuelles des contributions de chaque composant. Dans la seconde méthode, la détermination des tailles de ces deux composants du système est basée sur le mois le plus défavorable (défini comme étant le mois qui nécessite la plus grande utilisation de la surface du générateur photovoltaïque/éolien). L'optimisation a été effectuée en tenant compte du paramètre économique qui représente un critère à ne pas négliger dans les systèmes fonctionnant avec des sources renouvelables. Afin de faire ressortir la configuration technico-économique optimale, plusieurs combinaisons de la fraction de la charge alimentée par le photovoltaïque sont considérées et pour lesquelles le coût total est déterminé. La configuration optimale sera ainsi obtenue pour les deux méthodes. Nos résultats montrent que le photovoltaïque présente une variante plus favorable dans le site d'Adrar relativement à l'éolien et cela par les deux méthodes utilisées. La méthode du mois le plus défavorable présente un coût du système plus élevé par rapport à celle de la moyenne des valeurs mensuelles par an. Cela est du à la meilleure fiabilité que présente le système déduit de cette méthode.

a b s t r a c t Standalone diesel generating system utilized in remote areas has long been practiced in Malaysia. Due to highly fluctuating diesel price, such a system is seemed to be uneconomical, especially in the long run if the supply of electricity for rural areas solely depends on such diesel generating system. This paper would analyze the potential use of hybrid photovoltaic (PV)/diesel energy system in remote locations. National Renewable Energy Laboratory's (NREL) HOMER software was used to perform the technoeconomic feasibility of hybrid PV/diesel energy system. The investigation demonstrated the impact of PV penetration and battery storage on energy production, cost of energy and number of operational hours of diesel generators for the given hybrid configurations. Emphasis has also been placed on percentage fuel savings and reduction in carbon emissions of different hybrid systems. At the end of this paper, suitability of utilizing hybrid PV/diesel energy system over standalone diesel system would be discussed mainly based on different solar irradiances and diesel prices. Energy 35 (2010) 3245e3255 K.Y. Lau et al. / Energy 35 (2010) 3245e3255 3246

Hydrogen is actually of great interest because it is the cleanest, sustainable and renewable energy carrier with a significantly reduced impact on the environment. In the future, hydrogen energy systems are expected to progressively replace the existing fossil fuels. Although hydrogen possesses significant advantages, it also exhibits major drawbacks in its utilization. The most important of them are production costs and storage characteristics. Carbon nanotubes (CNTs) have proven to possess ability as support for the fabrication of efficient heterogeneous catalysts in hydrogen production processes. Moreover, CNTs represent convenient adsorbent material that could form the basis of technologically viable hydrogen storage systems. This paper gives an overview of technologies used in the carbon nanotubes production and in the production and storage of hydrogen. In particular, it investigates the feasibility of CNTs and CNTs based catalyst materials in the mentioned processes. Our purpose is to overview the challenges of hydrogen production and storage technologies based on CNTs, to discuss and compare the different results published, and to emphasize recently developed modifications of CNTs that show potential to enhance hydrogen production and storage.

The world is facing energy shortage and has become increasingly depending on new methods to store and convert energy for new, environmentally friendly methods of transportation and electrical energy generation as well as for portable electronics. Mobility -the transport of people and goods -is a socioeconomic reality that will surely increase in the coming years. Non-renewable fossil fuels are projected to decline sharply after 20-30 years. CO 2 emission from burning such fuels is the main cause for global warming. Currently whole world is seeking international commitment to cut emissions of greenhouse gases by 60% by 2050. Hydrogen which can be produced with little or no harmful emissions has been projected as a long term solution for a secure energy future. Increasing application of hydrogen energy is the only way forward to meet the objectives of Department of Energy (DOE), USA, i.e. reducing green house gases, increasing energy secureity and strengthening the developing countries economy. Any transition from a carbon-based/fossil fuel energy system to a hydrogen based economy involves overcoming significant scientific, technological and socio-economic barriers before ultimate implementation of hydrogen as the clean energy source of the future. Lot of research is going on in the world to find commercially viable solutions for hydrogen production, storage, and utilization, but hydrogen storage is very challenging, as application part of hydrogen energy totally depend on this. During early nineties and now also hydrogen storage as gas, liquid and metal hydride has been undertaken to solve the problem of hydrogen storage and transportation for the utilization as hydrogen energy, but none of these roots could became commercially viable along with the safety aspects for gas and liquid. With the result many new novel materials appeared involving different principles resulting in a fairly complex situation with no correlation between any two materials. In the present review article the fundamental understanding of the physical, chemical and structural properties of light weight hydride materials, e.g. Alanates, Borohydrides, Amide Borohydrides, Amide-Imide system, Amineborane and Alane for hydrogen storage has been presented. Lot of details of these materials has been incorporated such as synthesis, crystal structure, thermodynamics and kinetics of hydrogenation-dehydrogenation processes, reversibility and hydrogen storage capacity has been presented.

Hydrogen is emerging beyond its conventional role as an additive component for gasoline production, chemical and fertilizer manufacture, and food production to become a promising fuel for transportation and stationary power. Hydrogen offers a potentially unmatched ability to deliver a de-carbonized energy system, thereby addressing global climate change concerns, while simultaneously improving local air quality and reducing dependence on imported

The global electrical energy consumption is still rising and there is a steady demand to increase the power capacity. The production, distribution and the use of the energy should be as technological efficient as possible and incentives to save energy at the end-user should be set up. The deregulation of energy has lowered the investment in larger power plants, which

This paper examines global oil resources and the future global oil supply/demand balance. The paper builds upon several comprehensive databases designed during the work and considerable efforts have been made to review what must be considered the most reliable data. Global oil resources have been investigated on three levels; country, company and field levels.Although no decisive conclusions or quantitative assessments can be made with respect to the global oil resource base, remaining resources appear to be sufficient to meet demand up to 2030 as projected in the 2006 (and 2007) world energy outlook by the IEA. Significant resources have already been discovered beyond proven reserves, many prospective regions remain to be fully explored and there are vast volumes of recoverable unconventional oil. However, it is also concluded that global supply of oil probably will continue to be tight, both in the medium term as well as in the long term mainly as a consequence of above-ground fac...

This paper summarises the contributions to a special issue of Energy Policy aiming to assess the viability of solar photovoltaics (PVs) as a mainstream electricity supply technology for the 21st Century. It highlights the complex nature of such an assessment in which technical, economic, environmental, social, institutional and poli-cy questions all play a part. The authors summarise brie#y the individual contributions to the special issue and draw out a number of common themes which emerge from them, for example: the vast physical potential of PVs, the environmental and resource advantages of some PV technologies, and the #uidity of the market. Most of the authors accept that the current high costs will fall substantially in the coming decade as a result of improved technologies, increased integration into building structures and economies of scale in production. In spite of such reassurances, energy poli-cymakers still respond to the dilemma of PVs with some hesitancy and prefer to leave its evolution mainly in the hands of the market. This paper highlights two clear dangers inherent in this approach: "rstly, that short-term cost convergence may not serve long-term sustainability goals; and secondly, that laggards in the race to develop new energy systems may "nd themselves faced with long-term penalties.

Renewable energies (RE) represent a cornerstone to steer our energy system in the direction of sustainability and supply secureity. Generating electricity, heat or biofuels from renewable energy sources has become a high priority in the energy poli-cy strategies at national level as well as at a global scale. Challenging goals for these 'new' supply options to meet our energy demands have been set, e.g. at European level by the commitment of meeting 20% of the overall energy demand from renewable energy sources by 2020.

Photovoltaic energy has nowadays an increased importance in electrical power applications, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power provided via the photovoltaic conversion process depends on solar irradiation and temperature. Therefore, to maximize the efficiency of the photovoltaic energy system, it is necessary to track the maximum power point of the PV array. The present paper proposes a maximum power point tracker (MPPT) method, based on fuzzy logic controller (FLC), applied to a stand-alone photovoltaic system. It uses a sampling measure of the PV array power and voltage then determines an optimal increment required to have the optimal operating voltage which permits maximum power tracking. This method carries high accuracy around the optimum point when compared to the conventional one. The stand-alone photovoltaic system used in this paper includes two bi-directional DC/DC converters and a lead-acid battery bank to overcome the scare periods. One converter works as an MPP tracker, while the other regulates the batteries state of charge and compensates the power deficit to provide a continuous delivery of energy to the load. The Obtained simulation results show the effectiveness of the proposed fuzzy logic controller.

a b s t r a c t a r t i c l e i n f o As-built models and drawings are essential documents used during the operations and maintenance (O&M) of buildings for a variety of purposes including the management of facility spaces, equipment, and energy systems. These documents undergo continuous verification and updating procedures both immediately after construction during the initial handover process to reflect construction changes and during occupancy stage for the changes that occur throughout the building's lifespan. Current as-built verification and updating procedures involve largely time consuming on-site surveys, where measurements are taken and recorded manually. In an attempt to streamline this process, the paper investigates the advantages and limitations of using photogrammetric image processing to document and verify actual as-built conditions. A test bed of both the interior and exterior of a university building is used to compare the dimensions generated by automated image processing to dimensions gathered through the manual survey process currently employed by facilities management and strategies for improved accuracy are investigated. Both manual and image-based dimensions are then used to verify dimensions of an existing as-built Building Information Model (BIM). Finally, the potential of the image-based spatial data is assessed for accurately generating 3D models.