On the wind energy resources of Sudan

The imminent exhaustion of fossil energy resources and the increasing demand for energy were the motives for those reasonable in Sudan to put into practice an energy policy based on rational use of energy; and on exploitation of new, and renewable energy sources. After 1980, as the supply of conventional energy has not been able to follow the tremendous increase of the production demand in rural areas of Sudan, a renewed interest for the application of wind energy has shown in many places. Therefore, the Sudanese government began to pay more attention to wind energy utilisation in rural areas. Because the wind energy resource in many rural areas is sufficient for attractive application of wind pumps, and as fuel is insufficient, the wind pumps will be spread on a rather large scale in the near future. Wind is a form of renewable energy, which is always in a non-steady state due to the wide temporal and spatial variations of wind velocity. A number of years worth of data concerning wind speed in Sudan have been compiled, evaluated and presented in this article. The need for the provision of new data stations in order to enable a complete and reliable assessment of the overall wind power potential of the country is identified and specific locations suggested. This paper presents the background and ideas of the development of the concept as well as the main results, and experience gained during ongoing project up to now. In Sudan, various designs of wind machines for water pumping have been developed and some designs are presently manufactured commercially. Results suggest that wind power would be more profitably used for local-and small-scale applications especially for remote rural areas. It is concluded that Sudan is blessed with abundant wind energy.     

Assessment of solar and wind energy resources in Ethiopia. II. Wind energy

Using wind data from 21 meteorological stations with hourly or 3-hourly readings and 60 stations with monthly means, together with data from previous studies of neighbouring countries, a series of analyses were undertaken to illustrate the general availability of wind energy across Ethiopia. In order to calculate the wind energy density, firstly these 21 stations, along with 12 stations from neighbouring countries with hourly readings, were used to calculate the Weibull parameters, c and k. The Weibull distribution is shown to be a good approximation for the observed values in a majority of cases. Isopleths of the k values were then plotted, and from this the remaining 60 stations with monthly readings were then assigned k values. The wind energy density for each station was then calculated. Although the quantity of wind data is somewhat lacking, the results show that there is a potential for wind energy utilisation in some regions of Ethiopia.     

Assessment of solar and wind energy resources in Ethiopia. I. Solar energy

This paper describes how data from a variety of sources are merged to present new countrywide maps of the solar energy distribution over Ethiopia. The spatial coverage of stations with radiation data was found to be unsatisfactory for the purpose of a countrywide solar energy assessment exercise. Therefore, radiation had to be predicted from sunshine hours by employing empirical models. Using data from seven stations in Ethiopia, linear and quadratic correlation relationships between monthly mean daily solar radiation and sunshine hours per day have been developed. These regional models show a distinct improvement over previously employed countrywide models. To produce a national solar-energy distribution profile, a spatial extension of the radiation/sunshine relationships had to be carried out. To do this, the intercepts (a) and slopes (b) of each of the seven linear regression equations and another six from previous studies, completed in neighbouring Sudan, Kenya and Yemen, were used to interpolate the corresponding values to areas between them. Subsequent to these procedures, 142 stations providing only sunshine data were assigned their “appropriate” a and b values to estimate the amount of solar radiation received, which was then used to produce annual and monthly solar radiation distribution maps for Ethiopia. The results show that in all regions solar energy is an abundant resource.     

Renewable energy resources for electricity generation in Sudan

Electricity reaches only about 30% of Sudan's more than 40 M population; this mainly in urban areas. Hence, a major problem for rural people is the inadequate supply of power for lighting, heating, cooking, cooling, water pumping, radio or TV communications and security services. Petroleum product supplies, including diesel, kerosene and LPG are irregular and often subject to sudden price increases. Because of the inadequate supply of these fuels, women trek great distances into the forest to collect fuelwood, charcoal and biomass residues from animal and agriculture, account for more than half of total energy consumption. Most of this is utilised for cooking and heating water in rural and semi urban areas and by the urban poor. It is a need to provide alternative renewable energy sources to enhance women's participation in, and benefit from development. Household energy was the first energy sector that paid explicit attention to women and their energy needs. The contribution of women to environmental policy is largely ignored. Decision-making and policy formulation at all environmental levels, i.e., conservation, protection and rehabilitation and environmental management are more or less a male preserve. Women have been involved in promotion of appropriate energy technologies, primarily for rural population over the past 15 years. This article highlights the experience of working with rural people in seeking solutions for community energy needs through renewable environmentally friendly energy technologies.     

营口地区风能资源研究探讨

文中利用近半个世纪以来的观测资料,系统考虑风能密度大小的月变化特征、风力等级频率、极值风速、风向频率、能级频率、资源的稳定性等要素,对营口地区的风能资源特征进行分析。结果表明:1)营口地区的风能密度表现出显著的一波峰、一次峰的月变化特征,最大为4月,月平均风能密度为78.98W/m~2,次峰值出现在11月,波谷出现在8月。2)营口地区的风速在2级和3级出现的频率最高;有效风速出现的频率在50%以上。该地区20、50、100年一遇极值风速分别为20~25m/s、25~30m/s、35m/s左右。3)在1月和10月,营口地区的风向以西北向为主导,4月则以南-西南向为主导,7月以南向为主导。4)营口地区50W/m~2以上出现频率达到43.2%,100W/m~2以上出现频率为29.5%,150W/m~2以上出现频率为23.5%。5)营口地区风能密度的变异系数表现出显著的"M"状双峰型月变化,稳定性在3月和10月相对最差,变异系数在2.2左右,4~6月的稳定性最好,变异系数基本在1.2左右。     

Numerical simulation of solar wind energy towers

A numerical investigation is conducted to study the performance of solar wind energy towers. The two-phase flow of air and water droplets in the tower is modeled following an Euler–Lagrange approach with air representing the continuous phase and water droplets the discrete phase. Results demonstrate that energy towers perform best in hot and dry environments. Water injection at the inlet to a tower increases the strength of the downdraft current with the rate of increase diminishing as the flow at exit approaches saturation. At a given water injection rate and tower diameter the downdraft strength increases as the height increases, while it is independent of the diameter at constant height. Energy analysis shows that for towers of low height the cost of electricity is expensive and commercially unfeasible, while it is cheap for towers of heights higher than 100?m.     

尖山子风电场风能资源评价

根据尖山子风电场1999年7月～2000年6月测风资料，对风电场的风能资源各参数进行了详细地计算和分析，从而得出尖山子地区风能资源丰富，适宜建设大型风电场，具有较大的开发利用价值的结论。     

Assessment of utilization of wind energy resources in Nigeria

The study critically reviews the prospects and challenges of utilizing wind energy resources for power generation in Nigeria. The various initiatives by governments and researchers were surveyed and the nation is found to sit in the midst of enormous potential for wind harvest for power generation. The far northern states, the mountainous regions and different places of the central and south-eastern states were identified as good areas for wind harvest together with the offshore areas spanning from Lagos through Ondo, Ogun, Cross-Rivers to Rivers states along the Atlantic Ocean in the south–south. Despite this great potential and huge prospect, the country is found to still suffer from serious energy crises due to her over dependence on hydropower which also is susceptible to seasonal variation in the amount of water levels at dams. There is yet to be committed wind energy project for power generation on-going in the country. Several challenges bedeviling the development and utilization of wind energy resources were identified and suggestions highlighted to help pull the nation out of this lingering energy crisis.     

我国的风能资源在哪儿

地球上近地层每年的风能总量约为1.3×1015瓦,可利用的风能量至少为1012瓦,约为地球上可利用水能总量的10倍。我国的年风能储量为1.6×1012瓦,其中10%是可以利用的。     

佳木斯风能资源形成分布探讨

风能资源是清洁的可再生能源,风能发电是新能源领域中技术最成熟、最具规模开发条件和商业化发展前景的发电方式之一,也是目前清洁能源中利用最方便、最快捷、最少投入的可再生能源之一。已经成为世界能源可持续发展战略的重要组成部分。因此本文从风的形成原因、影响风速大小的因素、佳木斯风能资源的分布状况和可建风电规模（发展目标）等方面予以阐述,为佳木斯的风电发展提供理论参考根据。     

新疆太阳能资源及区划

分析了新疆太阳能辐射年分布状况和月分布状况。通过月总辐射分布曲线、月直达辐射分布曲线、月散射辐射分布曲线,分析了不同地区、不同月份太阳能辐射分布状况。采用三级区划指标对新疆太阳能资源进行了区划。第一级区划采用太阳能资源年总量;第二级区划采用水平表面直达辐射量(Qb)与总辐射量(Q)的比值;第三级区划采用环境温度和日照时数大于6 h的天数。通过三级区划划分了太阳能资源带、区;分析了带、区季节分布特征、日照大6 h的天数和日照气温大于10℃的天数。全面了解和掌握新疆太阳能资源状况,可为本地区的太阳能利用提供可靠的资料。     

青海省太阳能资源的开发利用

在调查了解青海省光伏发电产业发展情况的基础上,深入分析了青海省光伏发电产业的发展现状和存在问题,并提出了光伏发电产业健康发展的对策与措施,从而有效地促进青海省太阳能资源优势的发挥.     

Enhancing information for solar and wind energy technology deployment in Brazil

Brazil's primary energy matrix is based on more than 47% of renewables, and more than 85% of its electricity is generated by hydro power sources. Despite this large fraction of renewable energy resources, less than 0.3% of the national energy supply comes from solar or wind sources. This paper presents a diagnostic review on the penetration of the solar and wind energy technologies in Brazil. It also includes a survey of the latest government policies and incentives for renewable energies deployment by entrepreneurs, industry and commercial and residential consumers. In addition, the paper analyses how to best meet the requirements for policy support and information technology to boost the deployment of solar technology and wind energy in Brazil. This study was mostly based on results of a widely distributed survey covering key issues, and also by personal interviews carried out with key stakeholders in order to better understand the issues highlighted in the survey responses. The study pointed out some of the main obstacles to effectively promote and improve government policies and actions for investment in solar and wind energy market in Brazil.     

Combining wave energy with wind and solar: Short-term forecasting

While wind and solar have been the leading sources of renewable energy up to now, waves are increasingly being recognized as a viable source of power for coastal regions. This study analyzes integrating wave energy into the grid, in conjunction with wind and solar. The Pacific Northwest in the United States has a favorable mix of all three sources. Load and wind power series are obtained from government databases. Solar power is calculated from 12 sites over five states. Wave energy is calculated using buoy data, simulations of the ECMWF model, and power matrices for three types of wave energy converters. At the short horizons required for planning, the properties of the load and renewable energy are dissimilar. The load exhibits cycles at 24 h and seven days, seasonality and long-term trending. Solar power is dominated by the diurnal cycle and by seasonality, but also exhibits nonlinear variability due to cloud cover, atmospheric turbidity and precipitation. Wind power is dominated by large ramp events–irregular transitions between states of high and low power. Wave energy exhibits seasonal cycles and is generally smoother, although there are still some large transitions, particularly during winter months. Forecasting experiments are run over horizons of 1–4 h for the load and all three types of renewable energy. Waves are found to be more predictable than wind and solar. The forecast error at 1 h for the simulated wave farms is in the range of 5–7 percent, while the forecast errors for solar and wind are 17 and 22 percent. Geographic dispersal increases forecast accuracy. At the 1 h horizon, the forecast error for large-scale wave farms is 39–49 percent lower than at individual buoys. Grid integration costs are quantified by calculating balancing reserves. Waves show the lowest reserve costs, less than half wind and solar.     

An application of a combined wind and solar energy system in Izmir

In this work, a combined system which is produced electrical energy from both solar radiation via solar cells and wind energy by using wind turbine was studied. For wind energy, measurements of wind velocities at 12 m height were taken. Then, these values were calculated for 42 m by using Hellmann equation. After that, wind energy converted to the electrical energy. However, value of solar radiation from solar cells was taken at the optimum slope angle of collector which provided higher energy production for each 1 h during this application. Thus, obtained data from each system were used together for finding total energy. For this study, measurements, which would be used in calculation of wind energy and solar energy were taken for four years between 1995 and 1998 in Izmir. As a result, energy of the combined system could support each other when one of them produces energy insufficiently.     

拉萨地区太阳能资源变化特征分析及评估

利用线性回归分析法、10年滑动平均法和Mann-Kendall检验法,分析了拉萨地区太阳总辐射量和日照时数变化特征。拉萨地区太阳总辐射量呈现显著的下降趋势,一年中太阳总辐射量的分布呈现单峰型,5月最高,12月最低;年日照时数呈现微弱的下降趋势,各月日照时数差异不大,全年日照时数呈双峰型,10月日照时数最大,8月日照时数最小。对拉萨地区太阳能资源的分析和评估结果表明:拉萨地区多年平均年太阳总辐射量为7 473.3 MJ/m2,属于太阳能资源最丰富区;太阳能资源稳定程度指标为1.89,稳定程度高,且直接辐射占主导,有利于进行太阳能资源的开发利用。     

我国部分省(区)风能和太阳能激励政策

针对小型风力发电机组的使用者无法全部承担设备费用的问题，如今部分西部地区的地方政府，如内蒙古、甘肃、青海、新疆等省区，制定并实施了对微型风力发电机和户用光伏系统提供200—300元／台的补贴政策；还有的地方政府，为推广应用微、小水电技术、太阳能技术、生物质能技术和地热技术提供了大量的补贴。我国部分地区经济激励政策如下。     

青海省风能及太阳能资源测试

风能资源是重要的可再生能源,其利用完全依赖于风能资源的数据。UNDP／GEF加速中国可再生能源商业化能力发展项目,在青海开展了风能及太阳能资源实测项目,以进一步促进青海的风能利用。文章介绍了此项目的实施情况,对测得的数据进行了处理,对测试点的风力资源情况做了初步分析。     

Analytical performance and economic evaluation of residential wind or wind and solar powered heating systems

A performance and cost model for a variety of wind powered space and water heating systems for single family residences is presented. In addition to wind powered systems, combined wind and solar systems are modeled and compared to conventional and solar only heating systems. Analytical results are presented for a site in Amherst, Massachusetts. System capital economic details include an itemized cost breakdown of the wind heating system components. The results demonstrate that wind powered systems are presently competitive with electric based heating systems and will be competitive with oil or gas systems in the future.