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

ground from which a tilted axisymmetric concentrator accepts radiation is an ellipse, including also heliostats very distant to the tower producing a large image of the sun. The paper investigates asymmetric secondaries for these reasons. From the shape of the edge ray reflectors constructed for rays in the central south-north plane we conclude that a skew cone reflector might be appropriate for the field, and optimize its free parameters by means of ray tracing.

99100564 Optimization of four-colour photothermal converters used for power generation on interplanetary stations Dinu, C. A. and Badescu, V. International Journal of Energy Research, 1998, 22, (lo), 857-866. The perfbrmance of multicolour photothermal converters with four conversion units is dealt with in this paper. The power station consists in a combination multicolour converter-thermal engine. Outlined is the influence of the solar radiation concentration ratio on the system performance, as well as the effect of the sun’s zenith angle. The spectral distributions of optimum collector and radiator temperatures and the optimum temperature differences between the working fluid and the collector and radiator, respectively, are shown.

99100565 Sizing of a multi-tank solar water heater Sodha, M. S. et al. Internalional Journal of Energy Research, 1998, 22, (9), 777-790. This paper describes the experiment where the thermal performance of a multi-tank solar water heating systems under different climatic conditions, has been characterised by the solar fraction. An earlier model of the authors has been validated with experimental observations on different models of solar water heating systems. This model and the concept of solar fraction have been used to size the system for different climatic regions of country.

99100566 Solar gain characteristics of absorber-parallel transparent insulation materials Arulanantham, M. et al. Energy Conversion and Management, 1998, 39, (15), 1519-1527. Investigated are the solar gain characteristics of an absorber parallel slab of Transparent Insulation Material placed between the absorber plane and the glass cover of a solar collector/storage system. The transmittance of the cover system to solar beam radiation is determined by taking into account the absorption and reflection by the slab. Using a numerical technique the sky and ground diffuse radiation transmittances are computed. In order to compute the solar gain steady state one dimensional conduction with internal heat generation in the Methyl Methacrylate (MMA) slab is considered. The results arc compared with such transparent insulation materials as honeycombs, double glazing and single glazing. The honey- comb cover system shows the best performance, characterized by about 12% higher solar gain than the MMA slab.

99100567 Temperature-induced stresses in vacuum glazing: modelling and experimental validation Simko, T. M. et al. Solar Energy, 1998, 63, (l), I-21. Across a sample of vacuum glazing a temperature difference causes differential expansion of one glass sheet relative to the other. In vacuum glazing with a fused edge seal, this results in tensile and compressive stresses in the glass sheets, and bending of the structure. The model has been validated by comparison with experimental data for a well- characterized sample of vacuum glazing under accurately defined external conditions. Modelling data are presented for two glazing designs which have properties that are characteristic of the extremes of performance of this type of glazing.

Wind energy

99100566 A gaslfier integrated in a hybrid wind-blomass system Bilbao, R. et al. Making Bus. Biomass Energy, Environ., Chemical, Fibers Mafer., Proc. Biomass Conf. Am. 3rd, 1997, (2), 1425-1434. Edited by Overend, R. P. and Chornet, E. lnvolved in the Joule project ‘Hybrid Wind-Biomass system for rural electricity generation’ is the biomass research team in University of Zaragoza, the Innovative Technology Center in De Montfort University, as well as other partners. The global objective of this project is to develop a system to provide electricity for rural locations without the use of any form of fossil fuel. The project has been divided into a series of discrete sections, each of which is handled by a group. In this framework, the University of Zaragoza is working on the design and construction of a 50 kg/h downdraft air gasifier. Among the main characteristics of the gasifier, air is fed radially by three tuyeres, the bed is supported on an eccentric rotating grate in the bottom of the gasifier, and an agitation system prevents voidage formation in the bed. One of the newest features of the gasifier is that it is fired by ticking over, burning biogas with an air rate lower than the normal performance. The gasifier can quickly start automatically to process biomass by increasing the air flow when necessary.

99100569 Large-scale baseload wind power in China Lew, D. J. et al. Natural Resources Forum, 1998, 22, (3), 165-184. A novel strategy for developing wind power in large-scale (multi-GW) wind farms in China is presented in this paper. It involves combining oversized wind farms, large-scale electrical storage and long-distance transmission lines to deliver ‘baseload wind power’ to distant electricity demand centres. Baseload wind power is typically more valuable to the electric utility than intermittent wind power, so that storage can be economically attractive even in instances where the cost per kWh is somewhat higher than without storage. The prospective costs for this approach to developing wind power are illustrated by modifying an oversized wind farm at Huitengxile, Inner Mongolia. Using locally mass-produced wind turbines there are good prospects that wind power would be cost-competitive with coal power, on a life-cycle cost basis, while providing substantial net environmental benefits. Finally, the institutional challenges related to the prospect of large-scale wind energy development are addressed. Especially important are policies aimed at developing the capacity for mass production of as much of this technology in China as is feasible.

99100570 Short-term forecasting of wind speed and related electrical power Alexiadis, M. C. et al. Solar Energy, 1998, 63, (l), 61-68. The related electrical power of wind turbines and wind speed are forecasted. The work is focused on the operation of power systems with integrated wind parks. Artificial neural network models are proposed for forecasting average values of the following 10 min or 1 hour. Input quantities for the prediction are wind speeds and their derivatives. Also, spatial correlation of wind speeds and its use for forecasting, are investigated.

99100571 Morocco

Wind characteristics and wind energy potential in

Nfaoui, H. et al. Solar Energy, 1998, 63, (l), 51-60. Eleven sites in the windy regions in Morocco have been analysed for wind characteristics. The annual average wind speed for the considered sites ranged from 5 m/s to 10 m/s and the average power density from 100 W/m2 to 1000 W/m*, which might be suitable for electrical power production by installing wind farms. On an annual scale the observations of the distribution of hourly wind speed are better fitted by the Weibull hybrid distribution in contrast to the Weibull distribution. The wind power is estimated to be 1817 MW, which represents theoretically 11% of the total consumed energy in Morocco in 1994.

Others, including development, economics

99100572 generation

Biomass gasification for gas turbine-based power

Paisley, M. A. and Anson, D. J. Eng. Gas Turbines Power, 1998, 120, (2). 284-288. The development of cost-competitive technologies for the production of power from renewable biomass crops is a major goal for the Biomass Power Program of the US Department of Energy (DOE). The gasification of biomass provides the potential to meet this goal by efficiently and economically producing a renewable source of a clean gaseous fuel suitable for use in high-efficiency gas turbines. Discussed in this paper is the development and first commercial demonstration of the Battelle high- throughput gasification process for power generation systems. Projected process economics are presented along with a description of current experimental operations coupling a gas turbine power generation system to the research scale gasifier and the process scaleup activities in Burlington, Vermont.

99100573 Circulating fluldized-bed gasification of biomass Ising, M. et al. DGMK Tagungsber., 1998, 9802, 177-184. (In German) In combination with a gas engine or a gas burner, the gasification of biomass in a circulating fluidized bed is discussed as an option for the energetic use of biomass. In the circulating fluidized bed reactor wood was combusted with a minimum of air to avoid the formation of tar. The composition of the combustion gases of several experiments are tabulated. An economic analysis demonstrated that this technology for combined power and heat generation from biomass had advantages also in the performance range below 10 MW. Planned is the construction of a commercial pilot plant based on this technology.

99100574 Coordinating California’s efforts to promote waste to alcohol production Blackburn, W. J. and Teague, J. M. Appl. Biochemical Biotechnol., 1998, 70-72, 821-841. In California opportunities exist to produce alcohols from waste streams from various sectors of the economy. Government agencies have promoted waste-to-alcohol activities, but efforts have been inconsistent and inter- mittent. Often these efforts have been hindered by contradictory but mandate-driven policies. A prudent approach to co-ordinate state-wide efforts includes the development of an integrated state-wide policy to examine barriers that impede private sector business efforts to produce

56 Fuel and Energy Abstracts January 1999