Tanzania Daily News (Dar es Salaam)

Tanzania Wind Energy Potential Fairly High

RECENTLY, the German embassy in Dar es Dar es Salaam, in collaboration with the Dar es Salaam Institute of Technology (DIT), organised renewable energies technology exhibition.

The goal of the technology exhibition known as "renewables - Made in Germany" was to draw worldwide attention to the possible applications of renewable energies and to support technology transfers. At the fore of the exhibition is an overview of renewable energies technology with a special focus on the strengths of German suppliers and systems solutions.

The exhibition presents the advantages of various technologies, explains their functions, indicates various possible applications and documents the specific know-how of German companies, one of the world leaders in the renewable technology implementation. Wind energy has been used in many regions of the world for centuries.

Surpassed only by hydroelectric power stations, modern wind power plants are the second most efficient technology in renewable energy systems. The presence of several leading manufacturers makes Germany a pioneer in the continuing development of this technology and in increasing capacity worldwide. The German industry not only manufactures wind turbines and wind farm components, but also covers the entire wind energy value chain: site reports, certification and type inspections, planning and project management as well as the construction and operation of wind farms.

The German industry also benefits from a broad supply industry ranging from mechanical and plant engineering to the metal and electronics industries. The yield of wind farms is highly dependent on the wind speed. Since winds are stronger and steadier the further they are from the Earth's surface, turbines are mounted on the tallest towers possible.

As a rule of thumb, the yield of a wind farm increases by up to one per cent with every metre of increased height. In addition, a higher tower allows a turbine with a higher nominal output to be installed. Consequently, modern wind farms today achieve efficiency of up to 50 per cent. Large wind farms place special demands on the material. German manufacturers and developers are world leaders in the implementation and improvement of concepts for utilising wind energy.

One focus is on the ease of maintenance and the use of high-quality, tried and tested materials to facilitate high capacity utilisation of the systems. German manufacturers have developed two different designs for efficiently converting wind energy into electricity: generators with gears and those without gears. The status of June 2012 shows that the largest wind farm of German design type has a nominal output of 7.5 MW.

Given the consistent wind conditions and higher average wind speeds, the expected energy yields of offshore wind farms (at sea) are up to 40 per cent higher than those on land. Multi-megawatt offshore farms and their components are largely developed and manufactured in Germany and tested on a small scale on land.

Commissioning of the first commercial offshore wind farm in the Baltic Sea, Baltic 1, in 2011 and the first cluster in the North Sea, Bard Offshore 1, in 2011 were major milestones in the development of offshore wind energy use. Alpha ventus, Germany's first offshore wind farm with twelve fivemegawatt offshore wind turbines, has been feeding energy into the electricity grid since autumn 2009.

The excellent wind conditions in the wind farm, combined with high levels of availability of up to 97 per cent, enabled Alpha ventus to exceed expectations by 15 per cent, feeding in 267 gigawatt hours (GWh) of electricity in 2011. The use of small wind turbines is ideal for a basic electricity supply in offgrid regions. Small wind turbines are defined by the international IEC 61400- 2:2006 standard ("Design requirements for small wind turbines"), which describes small wind turbines as those with a rotor sweep area of less than 200 square metres, corresponding to a nominal output of some 50 kW at a voltage of less than 1,000 V AC or 1,500 V DC.

Their towers are usually not higher than 20 metres. Most turbines currently on the market generate outputs in the 5 to 10 kW range. Turbines from approximately 5 kW nominal output are economically viable if the proportion of self-consumed electricity is as high as possible, e.g. in agriculture or when used for sewage treatment plants or refrigeration plants. In Tanzania the Ministry of Energy and Minerals has started to assess the amount of wind energy available for local and foreign investors, who intend to engage in wind power generation.

According to the renewable energy official in the Ministry, the exercise has started in Singida, Njombe and Kilimanjaro regions to identify wind atlases, which would show areas that have potential energy for electricity generation. The project is hoped to attract more investors in the sector and stimulate the country's economic growth what with investors already showing interest particularly to Central Tanzania. The National Development Corporation (NDC) and Power Pool East Africa jointly own wind turbine projects and expect to extend power generation up to 300 MW in the coming five years.

Statistics shows the demand for power in Tanzania is growing by more than 50 MW every year, fuelled partly by the expansion of mining undertakings in parts of the country. Currently, hydroelectricity is the major source of energy in Tanzania over 50 per cent. The wind farm in Singida promises local power generation that is of an enormous benefit to the local economy, providing jobs during the construction phase and recurrent opportunities when fully operational. Wind power on a commercial scale is unknown in sub-Saharan Africa despite the existence of consistently strong winds, especially along the top of the rift valley, the mountain plateaus, which runs through East Africa from Ethiopia to Malawi and Mozambique.

In Europe, the industry is well developed. Germany, the European leader in terms of generation produces more than 25 gigawatts of power from wind turbines. Wind energy development in Tanzania started about 3 decades ago when some windmills were installed in several locations in the country to pump water for human and animal consumption and in a few cases for irrigation.

The initial analysed wind speed data revealed that the wind energy potential in Tanzania is fairly high. Until then, the nation lags behind in power generation with decades of continued rationing and blackouts, disastrous to business development as well as an ever increasing threat to social welfare and the quality of life.

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