07 Alternative energy sources (others, including development, economics)

prediction error of WAsP is about 4%. For the extrapolation with Monin Obukhov theory with different L and z0 estimations, it is 5-9%. The simple wind profile correction method, which has been developed, leads to a clear improvement of the wind speed and power output predictions. When the correction is applied, the error reduces to 2-5%.

05/00743 Investigation of indoor thermal comfort under transient conditions Kaynakli, O. and Kilic, M. Building and Environment, 2005, 40, (2), 165- 174. In industrialized countries about 90% of the time is spent indoors. In indoor, thermal comfort can be basically predicted by the environ- mental parameters such as temperature, humidity, air velocity and by the personal parameters as activity and clothing resistance. In this study, a mathematical model of thermal interaction between human body and environment was established and the effect of clothing and air velocity was examined under transient conditions. By the developed model, human body has been separated to 16 segments and possible local discomforts are taken into consideration. Using the model, changes in the sensible and latent heat losses, skin temperature and wettedness, thermal comfort indices were calculated. In a hot environment latent heat loss increases by means of sweating. Because of over wetted skin, comfort sense goes worse. Especially, at feet and pelvis skin wettedness reaches maximum level. Sensible and latent heat losses rise and the skin temperature and wettedness decrease with increasing air velocity.

where a similar amount of energy is generated by gas-fired plant. This enables the extra costs of the renewables scenario to be determined. The central estimate of the extra costs to electricity consumers is just over 0.3 p/kW h in current prices (around 5% extra on average domestic unit prices). Sensitivity analyses examine the implications of differing assumptions. The extra cost would rise if the capital costs of wind generation fall slower than anticipated, but would fall if gas prices rise more rapidly than has been assumed, or if wind plants are more productive. Even if it is assumed that wind has no capacity displacement value, the added cost to the electricity consumer rises by less than 0.1 p/kW h. It is concluded that there does not appear to be any technical reason why a substantial proportion of the country's electricity requirements could not be delivered by wind.

05•00747 Wind availability and its potentials for electricity generation in Tafila, Jordan Hrayshat, E. S. Renewable and Sustainable Energy Reviews, 2005, 9, (1), 111-117. In this paper, long-term wind speed and direction available at Tafila, Jordan (1990-2000) have been studied and analysed. The average wind speed was found to be equal to 4.4 m s a, which indicates the suitability - to a certain extent - of using only small size wind parks to produce electricity to fulfil the deficient electric power during the peak hours. The wind direction was found so variant, which makes it unique for installation of wind parks due to limited area of Tafila. The extractable power was found to vary from 27.36 to 34 W m -2.

05/00744 On the probabilistic distribution of wind speeds: theoretical development and comparison with data Li, M. and Li, X. International Journal of Exergy, 2004, 1, (2), 237-255. The probabilistic distributions of wind speed are a critical piece of information needed in the assessment of wind-energy potential, and have been conventionally described by various empirical correlations. Among the empirical correlations, the Weibull distribution has been most popular due to its ability to fit most accurately the variety of wind- speed data measured at different geographical locations in the world. This study develops a theoretical approach to the analytical determi- nation of the wind-speed distributions through the application of the maximum entropy principle (MEP). Although it has been used in a variety of fields, this is the first time MEP has been applied to the wind energy field. Under the MEP, the maximization of Shannon's entropy is carried out subject to the conservation of mass, momentum and energy associated with the wind flow. tt is shown that the present theoretical predictions agree very well with a variety of the measured data from different sources and have better accuracy than the Weibull distributions.

05/00745 Stochastic modelling in wave power-equipment optimization: maximum energy production versus maximum profit de O. Fal6o, A. F. Ocean Engineering, 2004, 31, (11 12), 1407-1421. The paper presents an optimization study for the mechanical and electrical equipment of an oscillating-water-column (OWC) wave power plant of fixed shoreline or nearshore type, equipped with an air turbine. The plant 's structure geometry is assumed to be given and the corresponding hydrodynamic coefficients are known as functions of wave frequency. A stochastic model is adopted for the energy conversion process from wave to air turbine, it being assumed that the system is linear. The optimization concerns the turbine size, represented by its rotor diameter D. Two alternative criteria are used: (i) maximization of the produced electrical energy, (ii) maximization of the annum profit. An example calculation is presented, based on the hydrodynamic coefficients of the OWC on the island of Pico, Azores, and on the aerodynamic performance curves of its Wells turbine. The influence of the following parameters upon optimized turbine size and rated power output is analysed: wave climate, capital costs of mechanical and electrical equipment, operation and maintenance costs, discount rate, equipment lifetime and price of electrical energy supplied to the grid.

05100746 Total cost estimates for large-scale wind scenarios in UK Dale, L. et al. Energy Policy, 2004, 32, (17), 1949-1956. The recent UK Energy White Paper suggested that the Government should aim to secure 20% of electricity from renewable sources by 2020. A number of estimates of the extra cost of such a commitment have been made, but these have not necessarily included all the relevant cost components. This analysis sets out to identify these and to calculate the extra cost to the electricity consumer, assuming all the renewable electricity is sourced from wind energy. This enables one of the more controversial issues - the implications of wind intermittency - to be addressed. The basis of the assumptions associated with generating costs, extra balancing costs and distribution and trans- mission system reinforcement costs are all clearly identified and the total costs of a '20% wind' scenario are compared with a scenario

Others, including development, economics

05/00748 A target group-specific approach to 'green' power retailing: students as consumers of renewable energy Gossling, S. et al. Renewable and Sustainable Energy Reviews, 2005, 9, (1), 69-83. An extensive body of literature exists on the obstacles that have to be overcome in green power retailing. In this article, target group-specific marketing is evaluated as a strategy to increase the share of residential customers of green power. A sample of students in the city of Freiburg, Germany was interviewed in order to assess their awareness of environmental issues, their willingness to change to green power products, and to better understand individual hindrances in changing the power supplier. The analysis shows that students are highly positive towards green power products, but for several reasons difficult to reach in marketing campaigns. Aspects to be considered in addressing this consumer-group include the students ' particular expectations towards green products, their living-conditions, price sensitivity, and their perception of the relative effort involved in changing the power provider.

05/00749 Biomass energy potential and future prospect in Sudan Omer, A. M. Renewable and Sustainable Energy Reviews, 2005, 9, (1), 1-27. Sudan is an agricultural country with fertile land, plenty of water resources, livestock, forestry resources, and agricultural residues. Sudan is an energy importing country and the energy requirements have been supplied through imports that have caused financial problems. Because of the economical problems in Sudan today, the Sudanese energy policy should be concentrated on assurance of energy supply, reliability, domestic sufficiency, and in time, on economic terms, and renewability. Energy sources are divided into two main types; conventional energy (biomass, petroleum products, and elec- tricity); and non-conventional energy (solar, wind, hydro, etc.). Sudan possesses a relatively high abundance of solar radiation, and moderate wind speeds, hydro, and biomass energy resources. Therefore as a renewable energy source, biomass (especially fuelwood) seems inter- esting because its share of the total energy production at 87% is high and the techniques for converting it to useful energy is easy. On the other hand, biomass may, however, see greatly expanded use in response to the environmental problems caused by fossil fuel use in the country. Like many tropical countries, Sudan has ample biomass resources that can be efficiently exploited in a manner that is both profitable and sustainable. Fuel-wood farming offers cost-effective and environmentally friendly energy solutions for Sudan, with the added benefit of providing sustainable livelihoods in rural areas. This article provides an overview of biomass energy activities and highlights future plans concerning optimum technical and economical utilization of biomass energy available in Sudan. Biomass has been proposed to have a central role to play in future, more sustainable energy scenarios. For this to become a reality, several real problems need to be overcome. In Sudan, as in other developing countries, modernization of biomass

110 Fuel and Energy Abstracts March 2005